SSSquid Tuning custom M30B34 chip about to install

Post here for mechanical and engine topics such as fuel issues, transmission problems, rough idle, exhaust, electrical issues, etc

Moderators: GRNSHRK, ron, bfons

Post Reply
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

I have just purchased a custom chip for my M30B34 from SSSquid Tuning and was wondering if anyone has already done this and can perhaps give me their opinion?

The chip I have ordered is a custom job to fulfil my particular esoteric requests rather than the standard job from his website, but nevertheless, it should be roughly comparable to a standard stage 1.0 tune if anyone else is running that in their M30B34?

I wasn't particularly looking for any great increases in power/torque, rather my #1 priority for wanting a custom chip was to get rid of the DFCO code that shuts down the injectors on closed throttle overrun. I don't like the hard step from idle speed powered drive to full-on compression engine braking when trying to drive slowly on the cusp of a closed throttle. It makes for undignified and unpleasant driveline shunting and transmission backlash wear with the constant back and forth between going too fast and going too slow with no happy middle ground. As such, SSSquid has made me a custom chip which does away with the DFCO by moving its action way up the rev range where it will never be noticed, stage 1.0 for mildly uprated stock engines with only Fritz’s Bits header, 95 RON/91 AKI fuel use and a mildly raised 6,300rpm rev limit.

Just wondering if anyone else with an M30B34 has tried the SSSquid chip and can report on whether they noticed any difference? I'm not expecting miracles and will be perfectly happy if just the DFCO code has been disabled. This chip is replacing my previous Mark D'Sylva EAT chip which doesn't disable the DFCO and doesn't play nice on cat-less, non-lambda, open loop 059 DME installations.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

I didn't realise that the overrun fuel cutoff could cause such intractable troubles. I would normally assume that there was some fault with the setup that was causing such symptoms, specifically with the throttle body, TPS, or perhaps with a worn/badly adjusted AFM.

On a closed throttle there shouldn't be 'idle power', there should be fuel in proportion to the (minimal) airflow except when it is cut off. If the overrun fuel cutoff cuts in very noticably, it may mean (for example) that the airflow (and thus the fuelling) was too high with a closed throttle. If it then cuts in with a lurch it can mean that (possibly in combination with a badly set throttle butterfly) the TPS is set badly, so that the fuel only cuts in again when the airflow (and thus the fuelling) is quite a bit higher.

When the fuel cuts back in for idle control at low RPM, the ICV opens, which boosts the airflow enough to hold idle even when the engine is cold and the AC is on.

Symptoms of a throttle body setting is that is too far closed include

a) that (esp when the engine is cold and/or the AC is on) the engine rpms drop to a very low level and then pick up again (when resuming idle)
b) the transition to part-throttle running isn't smooth

Both these things are caused by the ICV having to open and close a long way, quickly.


Symptoms of a throttle stop setting that is too far open include

a) that there is a sudden change in engine braking on a closed throttle when the fuel cuts/resumes
b) that with a hot engine, the idle is slow to establish and may not be 100% stable
c) that the transition into part-throttle running isn't smooth

In general the first thing that goes to pot if the TB/TPS/AFM are set up wrongly is the transition between idle and part-throttle running. [Same goes for TB balancing on M635CSi too, BTW]

The procedure is to set the TB to 0.5mm gap when the throttle is closed, and to lock that adjustment off. Then set the TPS to just actuate the idle contact as the throttle is closed. Finally, check the AFM is giving the correct readings at low airflow, so that the fuelling is set correctly.

If the car uses an O2 sensor and runs closed loop normally, this can mask all kinds of horrendous problems; it isn't a bad idea to set it up to run nicely open loop, and then to reintroduce the O2 sensor input.


If your new chip gives you other beneficial things as well, then great, but if it has been programmed to paper over the cracks in a basic setup problem then it isn't a very satisfactory situation; should the nature of the basic fault change in any way, you may not get the car to ever run right again, not without a new chip, anyway.

Do other folk recognise the reported fault? Did you need a new chip to fix it?

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

Brucey wrote: Sun Jul 22, 2018 10:40 am I didn't realise that the overrun fuel cutoff could cause such intractable troubles.
Yeah for me it does. It is entirely possible that I'm just far more sensitive and demanding than the majority in my dislike for the DFCO functionality. Anyway, that was my main reason for getting the chip in the first place. If you don't agree or can't see the worth in that, then that's fine, just ignore that bit. If you can't notice the ugly step in the driveline transfer from driven to driving in the mechanical linkages between the engine and the rear wheels when having to drive right on the cusp of an open throttle, then you won't see any worth in getting rid of the DFCO and you're very lucky to be able to not let it bother you. Just ignore that bit and tell me about your opinion of the SSSquid chip in the other respects if you have any real world experience of it.
On a closed throttle there shouldn't be 'idle power'
Shouldn't? According to whose rulebook? The DFCO was created to appease ever tightening fuel consumption regulations and emission control legislation. That's all. It's a nasty bit of code that Bosch knew very well was not ideal, but it helped to reduce the fuel consumption number just that little extra bit, to look good on the publications the marketing department wanted to produce to sell the cars. That's all. It's a compromise engineering solution to make the cars a bit easier to sell. After the car was sold, the 'correct' way of running the engine would be to get rid of the compromise and have the engines run properly like carbuettor engines did in the days before engines got strangled by emission and fuel consumption demands.
but if it has been programmed to paper over the cracks in a basic setup problem then it isn't a very satisfactory situation
There's no papering over cracks as you put it going on here. All three of my cars suffer the very same driveline shunting issue caused by the DFCO code. In the two with economy gauges you can also see visually exactly what's going on, because there's a wildly swinging needle that goes from one end of the gauge to the other rapidly as the DFCO cuts the injectors on/off which unsurprisingly coincides precisely with exactly when I feel the driveline snatching backwards and forwards as the torque is transferred back and forth between the wheels and the engine.

I know it works because I have a completely bog standard M635CSi chip and exactly the same chip with just 8 bytes of data changed to move the trigger point for the DFCO to around 3,500rpm instead of the standard 1,200 or 1,500 or whatever it is. Put the standard factory chip in and the car becomes impossible to drive at a steady, smooth 30-40km/h. Put the modded chip with 8 bytes of data different and the car becomes as smooth as silk, easy and sublime to drive instantly with absolutely no other changes at all. Don't even need to lift the bonnet. The only other difference you can notice is a very soft, muffled boom boom boom noise on long closed throttle overruns down hills or something like that coasting which is just purely the little bit of idle fuel still going in obviously not burning fully in the cylinders and a bit getting through to the exhaust and burning in there instead due to the M635CSi cams overlap, but it's very mild indeed and a very small price to pay for the benefit in driveability. The increase in fuel consumption that must also result is negligible and impossible to quantify.

I do admit though that I am probably a lot more sensitive than the average driver. I can also feel the DFCO working on brand new modern cars with much more sophisticated engine management ECUs than these old BMWs got. I hired a brand new Toyota Corolla with less than 5,000km on the clock one time and had to drive it through peak hour city traffic in Brisbane. At such slow speeds in stop/start traffic, the DFCO was very obvious and annoying to me after a while, and that was a brand new modern car with an automatic transmission. The fact is that 99% of people have simply learnt to accept that this is just how cars are supposed to be and it's normal. They don't question it because they don't know any different. The DFCO code is not widely known about or publicised, so nobody questions it. If you don't know what it is and don't know there's a solution to it, then you don't have any reason to believe it doesn't actually have to be this way and that your car can in fact actually be alot easier to drive and much smoother.

But that's all OK, I'm not trying to sell anybody on what I like my chips to do. If you're happy with your car driving the way Bosch and BMW made it do so to comply with artifical government imposed legislation of the time, then all power to you. Great. You'll be getting ever so slightly better fuel consumption that I will be. I would just like to hear the opinions of anybody who is using a SSSquid chip in their M30B34 with respect to the other advantages beyond the DFCO disablement customisation I asked for to be included in mine.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

in your first post you say that getting rid of the DFCO function was your #1 priority. I am just surprised that you find this an issue to start with. On this vintage of BMW there can be no end of drivability issues that bug folk but most of them are due to there being a setup problem of some kind. It occurs to me that since you have several cars you might have the same issue with all of them, but that it is (at least in part) due to the similar way they have been set up.

IIRC (and maybe I don't, so please refresh my memory) with the standard setup the fuel 'comes back' at about 1200rpm on closed throttle but is cut at higher speeds than that. When the fuel 'comes back', there is only enough fuel to be in proportion to the airflow into the engine. If you feel a noticeable surge at that point, it seems quite likely that you have too much air getting into the engine, and possibly that the mixture strength is not quite right anyway (possibly due to an AFM fault which would also explain the popping you are getting on the overrun with the new setup BTW).

On the overrun (above the idle speed) the only air getting into the engine should be past the TB(s). This should be a small amount of air only; by itself (i.e. with the ICV closed or blocked off) the engine should stall when it is cold and only manage about 400 or 500rpm when it is hot and there is no other load.

This amount of air is not normally enough to cause a noticeable surge on the closed throttle overrun. If you are seeing that, I would immediately suppose that the TBs are not adjusted correctly and/or that you have a (potentially unmetered) air leak. [ I'd test for this by blocking the ICV hose and seeing how much the idle speed drops by]. in any event (on a vintage BMW that doesn't have uncontrolled air leaks) simply by altering the TB adjustment will allow the air intake on the overrun to be reduced and therefore (if the fuelling system is working correctly) any surge to be reduced. You can carry on doing this until the engine threatens to stall when it is cold and it is transitioning to the idle state; eventually the ICV can't open wide enough, fast enough (as the engine speed drops through ~650rpm) to prevent a stall, there is so little air entering the engine on the overrun.

I have driven a car in this state and I would describe the fuel coming back at 1200 rpm as 'completely undetectable', i.e. there will still be lots of engine braking. If set up as per the book, I'd describe it as 'barely noticable', i.e. there will still be some engine braking rather than none. If this is not the case, then I'd suspect straight away that there is a fault of some kind in the setup or the condition of the EFI parts. Note that in a correctly adjusted system, having revved the engine up and then closed the throttle, the rate at which engine rpms decay to idle is barely slowed from 1200 to ~750rpm even though there is fuel in proportion to airflow in this range of engine speeds. This should tell you that the airflow on closed throttle is a very small amount. If yours isn't like this, I'd expect the engine not to slow to idle briskly (in the 1200 to 750rpm range) having revved it up.

If this kind of fault were commonplace then I would have expected to have heard of it (or noticed it/got annoyed by it myself) before now. I can only suppose that you are very sensitive to this kind of thing, or for whatever reason, that fault exists in your cars worse than it does in others. I am genuinely interested to find out which it is. Have others noticed it/got annoyed by it?

BTW if the car doesn't transition smoothly from closed throttle to slight positive throttle between 750 rpm and 1200rpm, to me this is a surefire sign that the fuelling is not set up correctly; something has to be out of adjustment or faulty, since there should be fuel (in exact proportion to airflow, which you are controlling precisely with your right foot) either way.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

Brucey wrote: Mon Jul 23, 2018 1:05 am in your first post you say that getting rid of the DFCO function was your #1 priority.
That's true, it is, however I don't expect it to be anyone eles's top priority and I'm not looking to convert anyone into believing it should be.
It occurs to me that since you have several cars you might have the same issue with all of them.
Not just my cars. Every modern fuel injected car. Doesn't matter the age, state of tune, milage, make, brand or model. All modern cars are setup to run this way. It is a (minor) fuel saving measure, it makes the fuel consumption look a bit better, it makes the CO2 emission number look a bit better and it also helps to prevent the catalytic converters possibly being damaged from unburnt fuel entering the exhaust system and the catalyst being poisoned by raw fuel/overheat. These are all good things when the company selling the cars is run by the marketing & accounting department instead of the engineering one. This is just reality. I know how the modern world works and why this is all necessary in this day and age and I'm not looking to buck this trend and argue that everyone else is wrong and I'm right. The world is run by environmentalists and accountants, not by engineers and nothing I say in here is going to change that. I'm realistic enough to know this is. All of these good things the DFCO achieves that make the environmentalists and accountants happy is however achieved at a (small) expense of smooth low speed driveability. I'm an engineer though, and I don't consider this an acceptable trade-off.

It's heresy to say this out loud these days I know, but I don't care about my car's CO2 number. Nor do I care about an infinitessimal increase in a fuel consumption number, and living where I live with the prevailing lack of annual road worthiness checks on vehicles before they can be licenced, I don't care about a tiny increase in risk to catalytic converter health either. But what I do care about is something that I can feel everytime I drive my car. I care about something that materially affects my enjoyment of driving my car. I agree that this probably makes me weird and over-sensitive, but I don't get any warm and fuzzy feeling in my trousers from knowing that when coasting my engine isn't melting any icecaps or endangering any polar bears. That does nothing for me, so through my eyes, the DFCO is all negative and nothing positive. It has no pros at all (because I don't place any value on CO2 or fuel consumption or catalytic converters), but it does have a con in negatively affecting driveability. If I can turn that con into a pro by getting rid of it, then that's a good thing to me.
IIRC (and maybe I don't, so please refresh my memory) with the standard setup the fuel 'comes back' at about 1200rpm on closed throttle but is cut at higher speeds than that.
You're quite right
engine RPM (any speed) + throttle open = Injectors on
engine RPM < ~1200 + throttle (any position) = injectors on
engine RPM > ~1200 + throttle closed = injectors off (this is the DFCO bit)

That's overly simplistic, it's a bit more complicated that this, but essentially that's how it operates. The computer does for example also take in to account a coolant temperature input as well, so that during the engine warm-up phase when coolant temperature is low, the DFCO is locked out from working. This is why the smoothest period of driving a modern car is right after startup and for the first few kilometers before the DFCO functionality kicks in. On much more modern cars than this website is aimed at, the transition from injectors on to injectors off at ~1,200rpm is handled much more cleverly and smoothly to be (almost) imperceptible. I think this is done by some form of torque limiting software code like a momentary ignition timing retard or perhaps sequential reactivation of cylinder injectors, so that the transition is smoothed out to such a degreee that it's almost a completely smooth curve, however this technology wasn't available in the mid-80's with the 1960's moon landing sort of computing power available in OBD-I. In the M30B34 engine and the 061/059 DME's, the step from injectors on to injectors off was far more binary. They're ON or they're OFF. There's nothing in between and if you're trying to drive right on that cusp of a cracked throttle pedal, then the injectors can end up being ON-OFF-ON-OFF-ON-OFF-ON-OFF in very rapid succession which does your guibo no good at all.
If this kind of fault were commonplace then I would have expected to have heard of it (or noticed it/got annoyed by it myself) before now.
I've already explained why this is probably not the case. The action of the DFCO is not commonly known. Simple as that. It's not published as a feature by the car manufacturers because it's not a selling point. Marketeers can't use it in their brochures because it's too complex and too technical for 99% of buyers to even understand, let alone care about. It doesn't sell cars. The only thing that sells cars are the end result numbers like the fuel consumption and CO2 number. Nobody cares how those numbers are attained or arrived at (at least they didn't until the whole VW diesel exposé drama exploded), they only care about what the number is and how that will impact how much they have to pay ongoing in insurance, licence and congestion charging fees. Nobody wants a lecture from a Bosch engineer about how the little bit of DFCO code he wrote will get the engine manufacturer over an arbitrarily invoked artificial line on a piece of legislation somewhere created by government, that will allow the company making the car to sell it in more markets around the world. The only people interested in listening to that lecture will be other Bosch software engineers and maybe the car company marketing department. That would be the driest, most boring lecture in history. You'd rather go to an all-day sales seminar for a toilet paper manufacturer on an industrial estate in Slough.
I can only suppose that you are very sensitive to this kind of thing
I am yes, and when you know it's not technically right or the correct and proper way of doing things from a purely engineering perspective devoid of artifical legislative requirements and marketing needs, then you focus on it and it needles you ever more until it becomes the biggest problem in the whole world. That's human nature. Well it is for me at any rate. I don't expect others to agree, but that's how it is for me.

At any rate, now that's explained, I'd still love to hear from anybody with a SSSquid chip who would like to chime in with their experiences of the tune in terms of the extra power/torque/driveability as compared to standard?
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

in fairness the operation of the overrun fuel cutoff is fairly well known in BMW circles; it is described in various manuals and has been discussed here (eg in relation to an unstable, surging idle). But it has not previously been described as causing significant problems with driveability, AFAICT. As I mentioned previously, when the system is set up correctly, I think you still have slight engine braking when the fuel comes back on the overrun; this being the case it doesn't itself cause driveline shunt; other things will do that though.

FWIW if you just use a chip on a standard B34 (Euro spec) engine there is something to be gained, but not that much. However if you have done things that alter the airflow through the engine, a new chip can make the most of those. It can also be made to work optimally with modern fuel (which is different from older stuff, even at the same octane rating). Whether this works well or not is dependant on the skill of the operator, the condition of the engine and EFI system, and (esp on older cars) his ability to spot any anomalous parts that may fundamentally undermine the accuracy of the EFI system regardless of the chip in use.

Needless to say if there is any variation to the standard setup/condition of the sensors, AFM, TB etc then the chip ends up being highly specific to your engine, and unless you understand exactly how the setup differs from standard, you may find yourself unable to make the chip work properly in the future. This is part of my concern about the overrun fuel cutoff; if it is having a more pronounced effect than normal, there may be a pre-existing fault, and you may end with a chip that works like a sticking plaster for this fault, but only if the fault is maintained in exactly the same way as normal.

For subtle faults that may throw you (and/or create the kind of problem you describe) there are several possibilities. For example is isn't unusual to end up with an AFM with worn spots in the track. This doesn't simply generate steady-state fuelling errors; my understanding is that the AFM signal is differentiated and the first (and maybe second) order derivative values are used to alter the fuelling. This is advantageous because normally, the flap takes a finite amount of time (about 100ms IIRC) to move; if the flap movement can be predicted, the fuelling can be altered so that (say) you don't get lean running in that 100ms as the throttle is opened. This is, if you like, the EFI equivalent of an accelerator pump type carb. It may do something clever as the throttle is closed (reducing AFM signal), too, but I don't know about that.

Anyway the effect of even a tiny glitch in the AFM signal may well be to throw a bit more fuel into the engine than it needs, because of the transient effect. Because the most worn spots in the AFM track are near idle and 'cruise' (warm engine) flap positions, the result is that a very slightly worn AFM can cause drivability issues at small throttle openings, even though the output of the AFM seems (mostly) to be good. Because the air demand of the engine (for small loads) varies with temperature, this kind of fault is often sensitive to whether the engine is fully warmed up or not, because the dodgy part of the AFM may or may not be involved in the 'pootling' regime, in which driveline shunt may be most annoying.

So if you are getting poor 'pootling' performance ( for this type of vehicle) the first thing I'd suspect is that the system isn't set up properly. The next thing I'd suspect (on a thirty-year old car) is that a sensor input is dodgy, specifically on these cars that the AFM reading is perhaps a bit erratic, and that is causing fuelling errors in the range of interest. To bottom that out, it is best to use a 'scope on the AFM signal.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cofred
Posts: 58
Joined: Wed Jul 24, 2013 5:38 pm
Location: Frisco, Tx

Re: SSSquid Tuning custom M30B34 chip about to install

Post by cofred »

Wow. I feel so ignorant and frankly stupid after reading this thread....but highly impressed all the same!
Heath
'85 M635
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

cofred wrote: Wed Jul 25, 2018 2:01 am Wow. I feel so ignorant and frankly stupid after reading this thread....but highly impressed all the same!
I felt the same when I read up on how catalytic converters work
http://www.bearriverconverters.com/data/CatOpp.pdf
http://www.journal4research.org/article ... I10020.pdf
http://www.ierjournal.org/pgcon/869.Imp ... alysts.pdf
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

I'm sorry Brucey, but I have to disagree with you. I wanted to wait until I had some hard evidence to go on with a DFCO disabled chip installed and tested before I went out on a limb, but I have this now and the difference is profound.

I've installed a DFCO disabled custom chip in my E32 740iL's M60B40 today and taken her for a long test drive. No other changes at all. Nothing. Completely bog stock engine. This car is exactly as she rolled off the production line with the only change being the wheels + tyres as you can see from the photo. For reasons of tyre availability it was necessary to make a change to 16" from the OE 15" and so I did this as close to factory spec as possible by putting E38 wheels on. The rubber is Continental which is also what the car came with brand new. So this is probably the closest, most unmolested original specification E32 740iL you'll ever come across. Even the rear SLS suspension still works without leaks and has not been converted to standard shocks. You simply will not find a more perfect example test bed to do a before/after comparison between a stock BMW chip and a modded chip than this car.

The car's 26 years old and it has never been easier or driven smoother than it does now. Absolutely incredible. Right from the get go straight from first fire up after installation it was instantly obvious things were going to be much better. The idle is sewing machine smooth.

The DFCO is gone completely too. I actually have to adjust my driving style a bit now because it's just so much easier, I don't have to be so gentle and careful with my throttle movements to try and drive around the problems caused by the standard tune. If I want now, I can be a binary footed, ham fisted rock-ape with the mind of a rabid baboon in driving style and the car will just take it all in and smooth out my worst efforts at throttle control and make me look like a hero chauffeur instead. It really is that good.

I can't say there's a lot more power or torque, because this is the mildest version tune for this bog stock engine, so that's to be expected, but the car is definitely more enthusiastic and willing at any speed. I'd say there's just enough more power/torque to bring the car's performance back to what it was with the lightweight 15" style 5 wheels it had before I loaded it up with the very heavy Style 61 E38 wheels with Continental SSR run-flat tyres she has now. There was a noticeable dulling of performance when I did this wheel/tyre swap, and that has now been counteracted again with this chip.

So outright performance was never the goal here and for sure it's not going to frighten anyone or worry your Ashley & Martin, but the increase in smoothness is very welcome indeed. As an added bonus fuel consumption is well down now that there isn't big dumps of fuel going into it each time the injectors are switched back on again after a DFCO interruption. Fuel consumption on the stock chip began with a 13 and got dangerously close to 14. It now begins comfortably with an 11 and down the freeway this afternoon, I saw 9.7

I have never, ever seen a single digit fuel consumption figure on this car before. So sorry Brucey, but the cracks and problems you refer to are actually created by the stock chip. I only realise now how much I've been driving around the problems of the stock chip now that I have a proper chip that runs the engine like it always should have been. It really is so different that an adjustment of thinking about what you do with your right foot is required. I don't need to be anywhere near as careful and tentative as I had to be before trying to avoid the DFCO cutting in.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

I'm glad it works for you but I am bound to point out that you should be disappointed if the chip 'didn't work' given that it was just programmed for your car.

However that doesn't mean that there wasn't (and isn't) something weird in the way your car is/was set up, and the chip has just programmed its way around those things. If that is the case (and I sincerely hope it isn't for your sake) if the non-standard setup changes in any way, your nice new chip will stop working unless you can replicate the exact (unknown) setup you have right now. [That you never got 'single figure' consumption figures before (you are talking l/100km, right?) suggests that might well be the case, BTW.]

If the overrun fuel cutoff were such a major PITA as you describe, you would doubtless find myriad posts complaining about it. These are conspicuous by their absence, meaning there is most likely something special about you and/or your car.

I am constantly amazed at how badly a lot of people's cars are set up. Just the other day I was looking at an M3 which the owner had lavished a fortune in time and money on (making it one of the nicest looking standard ones in the country) and frankly the set-up of the TBs and the TPS etc was absolute crap. This was despite various folk having a go at it using vacuum gauges and Christ knows what else. Needless to say it drove really badly, lurching about as it went on and off a closed throttle and (for the reasons I have explained at length above) the overrun fuel cutoff was obvious and annoying.

I was (using Mk1 grey matter, a screwdriver, and a single spanner) able to improve matters considerably in less than five minutes. Doubtless a complete cure would have taken a little longer.

That chap could also have 'cured' his car by getting a custom chip made for it but it would have been a complete waste of money. The chances of ever replicating the dodgy setup he had exactly are nil.

I have seen plenty of other similar instances too. Quite a lot of reputable tuners spend as much time fixing basic problems as they do programming the system to optimise performance.

Thus I repeat my earlier advice; if your car is manifesting erratic behaviour that is worse than normal for that type of car, get it sorted out before doing anything else. Get a second (unbiased) opinion on whether your car is 'normal' (for that type) or not. There is stuff-all point in getting a chip burnt which just works its way around a load of pre-existing setup problems which cannot be exactly reproduced later on.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

Brucey wrote: Wed Aug 01, 2018 8:08 pm I'm glad it works for you but I am bound to point out that you should be disappointed if the chip 'didn't work' given that it was just programmed for your car.
It's an off-the-shelf standard catalogue tune chip from an aftermarket tuner with the only 'custom' modification to my specification being the addition of DFCO disablement. It is not as you seem to be thinking a fully customised chip programmed on a rolling dyno setup with a laptop computer connected giving live feedback as you see in youTube videos.
However that doesn't mean that there wasn't (and isn't) something weird in the way your car is/was set up
You keep harping on about this as if there's an infinite number of settings that can be made with these cars and unless you have some sort of magical, devine BMW whispering skills to 'tune' them to within a bee's dick of absolute perfection, then your car isn't 'set up' correctly and you're just compounding errors from then on. Sorry, but that's crap. If the adjustments on these cars were so ridiculously fine as you seem to be suggesting, then once you attained that level of perfection, it would be so fragile a setting as to not last 5 minutes before the ravages of temperature, vibration and variable air quality as experienced in the real world of an operating engine bay had upset it again. You would simply not be able to maintain that perfect state of tune for a period of time acceptable to any owner. The reality is that the BMW cars are far more robust and well engineered than you give them credit for. These are not Triumph TR6's with Lucas fuel injection. There are standard parts in standard shapes than go into correspondingly sized standard holes. There are no magic settings here to the degree you're trying to suggest are why I notice the DCFO interaction. My car is 'set up' by two BMW trained technicians (from the UK no less). Correct standard parts are used throughout. The (original from new) TPS wore out only 9 months ago confirmed on oscilloscope and replaced with brand new part by them. That made absolutely no difference to the degree of annoyance of the DFCO interruption. You like to keep ignoring the fact that I notice the DFCO on all brands and all makes of modern cars. Are you suggesting the brand new Toyota Corolla I hired, the 2007 model AH Opel Astra I also own, my brother's Ford Mondeo, the neighbour's brand new Subaru Imprezza and the Volvo S60 I just sold for her, are also 'set up' incorrectly too in exactly the same way as my 740iL even though none of them go to the same workshops or are worked on/serviced by any of the same people? That's what you have to be suggesting, because I notice the interruption of the DFCO on all of them. To suggest that would be frankly absurd in the extreme and borderline OCD. It is true that the 740 is most noticeable and the worst offender, but it's also the oldest by more than a decade and has the earliest generation of ECU/DME by a considerable margin, so I'm not at all surprised that its DFCO implementation is also the most binary and blunt in activation.
If the overrun fuel cutoff were such a major PITA as you describe, you would doubtless find myriad posts complaining about it.
I agree and I can't explain this. As previously suggested though I can only presume that I am a particularly sensitive driver with particularly adept throttle control who notices (and is annoyed by) the engine doing things of its own accord that my foot is not telling it to do. My car has been driven by others (including my BMW mechanics of course) who say they can notice nothing wrong with the way it drives and in fact complimenting it on how smooth it is - with the standard OE chip installed. When I installed the new chip and they take it for a second drive, they can immediately tell the difference and say they can't believe how much smoother and easier it is to drive. That's an experiment and example of human nature in action to witness right there. Most people won't believe there's anything wrong until they personally witness something better for themselves.

It's human nature. People don't want bad news. They don't want to believe their car isn't driving as well as it can do. You're a prime example of this phenomemon Brucey by continuing to insist there must be something fundamental wrong with my car despite me telling you it is noticeable by me on every modern car. They've spent a lot of money over their ownership payng for parts and expertise to keep their car running exactly the best it ever possibly can according to the manufacturer's specs all the time believing that means perfectly and the best it can ever be, as if time and knowledge and government legislation is frozen and stands still from the moment the car rolled off the production line. But those things don't stand still. Just ask Microsoft or any other software author whether the first copy of their software was the very best and most bug-free it could ever be and that there was never any room for improvement from that moment on. If you check your computer for the number of updates it's had since you installed it, you'll know this premise is completely false.

It's human nature to convince yourself there's nothing wrong and that's just how cars are supposed to drive. The human mind is a powerful thing. Even if you do notice the DFCO kicking in each time you have to take your foot off the throttle for the tailback of red brake lights or the next red traffic light, you know your car is 'perfect' because you shower it with so much love and money and attention to be exactly as BMW intended, so you ignore the jerk in the driveline as your engine temporarily stops being an engine and becomes a PD reciprocating air pump driven by the rear wheels for a few seconds before becoming an engine again as you come to a full stop, and convince yourself it's nothing abnormal and that's just how things are supposed to be. You don't want to believe that jerk is anything wrong because you can't convince your mechanic there's anything wrong "We've checked everything and it's all within BMW specs, there's absolutely nothing wrong with your car. This is how it's supposed to be. It's by design that jerk happens, there's nothing we can do about it". Since there is no easy solution, in your mind you have to accept it as normal.

Since it's a fundamental included part of the code that runs the engine, 'fixing' the driveline shunting is really, really hard and you need mad machine language coding skills to solve it. This is not something you're going to find at your local workshop.

The new chip has solved more than just the DFCO annoyance. The standard OE chip has always (for the last 20 years of my ownership experience) on key turn, cranked the engine for maybe as much as 1500ms before firing into life. This is by Bosch design to presumably generate some oil pressure via the starter motor before the pistons take over. Then after starting, it will immediately rev up over 1,000rpm from stone cold and then settle down to normal idle over a few seconds. This is perfectly 'normal' and probably by design to quickly establish stable oil pressure for all markets where the car was to be sold. This is probably a necessary start process for cars sold in cold countries. My Astra, the next door neighbour's Volvo and Subaru all do exactly the same thing from stone cold. It's completely unnecessary where I live. The new chip starts the engine instantly upon key turn. It's like one of those modern stop/start cars now. There is barely any cold cranking at all now. It just fires into life as soon as the key switch makes electrical contact. Better still it doesn't overrev anymore either. It just goes immediately to a perfectly stable 5-600rpm idle as normal.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

OK thank you for clarifying that your custom chip is custom in only one respect.

As I explained earlier there are small gains to be made over standard for all kinds of reasons, mainly to do with how petrol was then and how it is now.

A lot of the anomalies you describe are attributable to things that are not quite right with the setup.

The cold start surge you describe in combination with the delayed start is explicable by a combination of several things.

1) the way the cold start injector is managed and
2) possible variations in fuel supply
3) Basic TB setup


Delayed starts from full cold (i.e. when the cold start injector is firing) are caused by faults in the cold start injector and/or a tiny air leak in the fuel delivery/fault in the check valve. In the latter cases the system gets air in it when standing (but doesn't leak fuel out at any rate when the engine is running). The result is that because the fuel pump only runs when cranking (which might be different with a revised chip?), it takes a couple of seconds to refill the fuel rail with fuel and to pressurise it, during which time the engine won't start. To diagnose a tiny leak of this kind, you can run the fuel pump manually (by jumping the fuel pump relay connections) for a few seconds before trying to start the car. If the car then starts promptly, you know that there is a fault in the fuel system. With no fault of this kind the engine ought to fire instantly on a cold start (sort of 'zikka-brumm' not 'zikka-zikka-brumm' even) and the idle should instantly settle to the correct speed. Mine did this recently after not having been run for several months.

Different CSIs work differently and BMW specced different ones for different markets, It isn't that unusual to find that the car won't start quite as well as normal if the temperature is only just high enough that the CSi doesn't fire. Obviously if the CSi only fires for one second, and it take two second for the fuel rail to pressurise, the starting performance will be very poor indeed.

During warm/hot restarts the CSI isn't working and fuel is only delivered to the engine pro-rata with measured airflow during cranking. If the TB is set too far closed at idle, and/or the ICV doesn't open during cranking (I think it won't open quickly if the cranking volts are low), or there is an air leak or a tiny fault with the AFM, you won't get enough measured airflow and/or fuel into the engine, and the car won't start instantly. A clue that there is a fault of this kind is if the engine starts better with a little throttle. If it only starts when the ICV has fully opened, the idle won't stabilise instantly like it should do, it will surge.

During very hot restarts the above applies but in addition the fuel rail may get so hot that the fuel vaporises.


So anyway when you reprogram the chip you have all kinds of ways of frigging the system which BMW didn't originally have access to. I'd be interested in knowing which of these have been utilised, but it may not be obvious and they may not be telling. For example
1) it may be possible to run the fuel pump briefly before cranking, thus avoiding fuel supply problems
2) if you assume that the engine is not going to be emission checked or is to be emission checked at a specific rpm/load only, you can 'cheat the system' and make all kinds of faults appear to, er, disappear.

I'm no expert in the latter but for example
- you can set a minimum threshold for fuelling (that 'makes sense') irrespective of the AFM signal, at low rpms (below idle rpms). This causes the engine to be less likely to stall; even if the AFM is indicating a (nonsensical) zero airflow, it is still getting fuel this way.
- you can 'aim rich' at low throttle openings and this will make for smoother running, more tolerant to minor variations in mixture strength that might otherwise arise

- you can alter the ignition timing. This one is really devious. It works so well that (on a race engine without an auxiliary air valve or idle control valve of any kind) the idle can be pefectly stable within a small range, even though the loads on the engine (eg oil drag varying with temperature, alternator etc) are varying. The way this works is that the volume airflow can be set to be constant with rpm and the fuel can be set (via temperature compensation mainly) to be pro-rata with the mass airflow. However the ignition timing hugely alters the torque generated by burning any given amount of fuel (less advance means less torque, basically, with the fuel still burning as the exhaust valve opens perhaps). This may screw the emissions in certain places on the 'map' but it also means that by programming a very steep slope in ignition timing variation with rpms near the idle point, you can artificially add stabilisation to the idle speed, and/or alter the rate at which idle is acheived. Someone who is as cunning as a weasel could overlay this with the standard ICV operation, still allowing the ICV to make the (slow, overshooty) changes in idle speed but the ignition timing variations can have an instant effect if you want them to.

So anyway, thinking about it, a cleverly programmed chip could mask all kinds of anomalies if the chap doing it set his mind to it, in ways that BMW might not have been able to originally.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

After spending what seemed like an eternity waiting for the Autologic computer to go through and read every single system on my car in sequence (these old Motronics are so slow) this is the only error it could come up with. This is post-installation of the new chip and there might be a very minor issue I've felt in some rare driving situations that causes a slightly hard and abrupt shift of the automatic from 1st->2nd gear. This reported fault and my description of an occassional hard 1->2 shift are being investigated by the chip supplier for resolution.

Image

Apparently the DFCO code is actually used by the DME in momentarily backing off the engine torque to smooth the shift changes, so in effectively disabling it, this might have introduced a new 'problem' in the 1->2 gear change harshness. That said, the chip author is confident of being able to fine tune the chip to solve the hard 1->2 shift without reintroducing the overrun DFCO annoyance and without slowing down or altering any of the other perfectly crisp, quick and seemless gear shifts after 2nd.

It is worth noting, that I could also induce a hard thump of a gearshift from 1->2 even with the OE chip installed too. It would happen if transitioning very quickly from no throttle+moving+1st gear to opening throttle+transmission load (going up hill). Such a predictable situation exists for me unfortunately quite regularly as my drive home requires braking downhill to an off-camber corner to a speed slow enough to force the auto to shift down to first gear. Then immediatey on corner exit the intersecting road goes steeply uphill and curves at the same time. It is at the apex of the new curve just after the corner that the transmission shifts back up again to 2nd and will go thump with a corresponding seat punch in your back as a result. It is only in this very specific driving situation that this occurs. It does not happen at any other time.

It seems the combination of braking, shift down to 1st gear followed rapidly by cornering, uphill transmission load, new acceleration and further cornering is enough of a combination to confuse the transmission into being caught off-step and left rapidly trying to gather itself up again. All of this is done with the gear lever in 'D' and in Economy transmission program mode. There is no manual driving of an auto happening. I believe all the new chip has done is highlight a pre-existing deficiency of the stock OE chip programming to make it more obvious and even easier to induce.

All that said, even if it can't be solved, I would still take the new chip over the stock one every day of the week. The benefit of the far quicker and more responsive gear changes far outweighs the drawback of an occassional hard shift from 1->2 induced by rapid switching from braking to acceleration under load from 1st gear. The 1->2 gear shift with the OE chip is ridiculously slow and delayed by I reckon as much as 1500ms. It's smooth as silk 99% of the time, but it's also unbelieveably and irritatingly slow too. The momentary hesitation in acceleration taking off away from the traffic lights as the gearbox has a long think about which gear comes after 1st is akin to manual transmission drivers of old taking their time clutch shifting from 1st to 2nd half way across the intersection. If you have an eye on the rear vision mirror, that giant 4WD behind you with the driver texting on their phone gets awfully close to punching the tow hook I have protecting my rear bumper as the auto has a long hard think about how to change from 1st to 2nd gear with the stock OE chip.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

maybe the programming of the gearbox varies with build date or something. On my EH autobox car, the 1-2 shift doesn't seem to be particularly slow, unless you have barely any throttle applied, in which case you are by definition not in any hurry.

If you are in a hurry, in my car this shift happens when you are doing about 55mph anyway, at which point almost anything that was behind you is now a long way behind you.... I think this shift backs the gas off for no more than about half a second (during hard acceleration), but I have not measured it accurately.

BTW if you are pootling in traffic the gearbox won't shift automatically into 2nd gear below a certain speed (which is about 30mph indicated in my car). This is annoying, for sure. However I have discovered that momentarily selecting 3-2-1 on the EH box forces the shift into 2nd provided you are doing at least 20mph or so and don't have a lot of throttle applied.

FWIW on cars with EH boxes, the TPS contains a throttle angle sensing potentiometer that only talks to the gearbox ECU. If the TPS (or TB) is set up badly or gives bad signals, unplanned and/or delayed shifts can result. Specifically if the TB setting is wrong (which causes all kinds of issues with the transition in and out of idle/overrun fuel cutoff BTW, as previously described, and may explain your clunking), the gearbox ECU can read the throttle as being differently open than it really is, which I think can lead to delayed shifts on light throttle.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

Brucey wrote: Fri Aug 03, 2018 10:07 amBTW if you are pootling in traffic the gearbox won't shift automatically into 2nd gear below a certain speed (which is about 30mph indicated in my car). This is annoying, for sure. However I have discovered that momentarily selecting 3-2-1 on the EH box forces the shift into 2nd provided you are doing at least 20mph or so and don't have a lot of throttle applied.
Don't know what an EH gearbox is, but mine has a ZF 5HP30 in it and this behaviour you describe only happens when the coolant is cold. Once the engine reaches normal operating temperature the gearbox shifts normally including upshifts to 2nd even while just coasting along at idle speed with no throttle at all in traffic.
the TPS contains a throttle angle sensing potentiometer that only talks to the gearbox ECU. If the TPS (or TB) is set up badly or gives bad signals, unplanned and/or delayed shifts can result. Specifically if the TB setting is wrong (which causes all kinds of issues with the transition in and out of idle/overrun fuel cutoff BTW, as previously described, and may explain your clunking), the gearbox ECU can read the throttle as being differently open than it really is, which I think can lead to delayed shifts on light throttle.
This is exactly what wore out on my TPS 9 months ago. The conductive tracks of the potentiometer in the TPS had finally been eaten away by so much spark errosion they could no longer maintain a constant stable signal. We could see it on the oscilloscope we connected it to in the workshop. We could rotate the spindle by hand and watch the trace of the screen being all noisy with lots of peaks and troughs. It looked like the price/time graph of a cryptocurrency. A new TPS produced a perfectly smooth curve by comparison.

On cracking the old one open I can tell you the technology inside is no more or less complex than the windscreen wiper motor in an E24. You know when your wipers start juddering across the screen stopping and starting and you need to clean/replace the copper grease inside the tracks and conductive arms? That's exactly the same thing going on in a much smaller scale inside the TPS. The only difference is that when it happens in a TPS, it sends the gearbox immedately into limp-home mode, stuck in 3rd gear. It's actually good that it stays stuck in 3rd gear, because if it did change gear it would almost certainly break your transmission and/or driveline. Without control of the engine torque for shifts, the 5HP30 shifts gear with full force (control valves all wide open for full hydraulic fluid pressure changes). Even at just idle speed when shifting from D-R-D-R to manoeuver the car into a workshop, the shifts are so hard and forceful they can be heard two workshops away and people come out of their receptions to see what the hell is going on. With full open throttle driving conditions, if the transmission did full pressure changes like that, I can easily imagine the gearbox just expoding into schrapnel internally.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

I am slightly confused; I thought we were discussing an M30B34 engine as per your first post and the thread title (presumably in an E24). If an auto, this would have a (4 speed) ZP-4HP22-EH box behind it, if built after a certain date. The EH (electro-hydraulic) variant has a control knob that selects between Sport, economy and 3-2-1 modes. The earlier (non EH) ZF 4HP22 gearbox has no ECU, no electronic controls and no mode selector knob.

The (five speed) ZF 5HP30 gearbox was introduced in 1992 and is only found behind M60, M62 engines etc.

FWIW there are at least two different versions of the (4HP22-EH autobox) TPS. The standard one fitted before a certain date sits underneath a large rubber boot, and the limit switches (for idle and WOT) are independently adjustable. The potentiometer that reads throttle angle has a small amount of float (radial adjustment) on the mountings and a clearance on the centre part too.. This means that the unit can be positioned so that the wiper arm works over a different (unworn) part of the carbon track if the mountings are moved slightly. Through a combination of this adjustment and the occasional squirt of WD40, the original potentiometer on my car has continued to work OK even though it has gone bad (intermittent signal) a couple of times. Mileage is currently about 165000 miles (about 265000km). Later cars (B35 motors) use a small black unit with a seven-wire round plug on the side of it. Wiring harness plugs and mountings aside, the two parts do the same job as one another.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
DRPM635CSi
Posts: 280
Joined: Thu Jul 09, 2015 6:50 am
Location: Perth, Australia
Contact:

Re: SSSquid Tuning custom M30B34 chip about to install

Post by DRPM635CSi »

Brucey wrote: Sat Aug 04, 2018 11:04 pm I am slightly confused; I thought we were discussing an M30B34 engine as per your first post and the thread title (presumably in an E24).
Scroll down to mid-page and read my post from Mon Jul 30, 2018 5:56 pm where this was explained in detail.
The potentiometer that reads throttle angle has a small amount of float (radial adjustment) on the mountings and a clearance on the centre part too.. This means that the unit can be positioned so that the wiper arm works over a different (unworn) part of the carbon track if the mountings are moved slightly. Through a combination of this adjustment and the occasional squirt of WD40, the original potentiometer on my car has continued to work OK even though it has gone bad (intermittent signal) a couple of times.
My UK BMW dealer trained mechanic actually suggested he could try to do this for me to get me temporarily back on the road while I sourced a new TPS from a location less ridiculously expensive than Australia. I decided however that I didn't want to paper over the cracks of a dodgily set-up car, so I paid the money and got him to install a brand new genuine TPS part from the dealer in a BMW bag with the BMW roundel logo on it.
Brucey wrote: Wed Aug 01, 2018 8:08 pm However that doesn't mean that there wasn't (and isn't) something weird in the way your car is/was set up, and the chip has just programmed its way around those things. If that is the case (and I sincerely hope it isn't for your sake) if the non-standard setup changes in any way, your nice new chip will stop working unless you can replicate the exact (unknown) setup you have right now. [That you never got 'single figure' consumption figures before (you are talking l/100km, right?) suggests that might well be the case, BTW.]
You seem to think a single digit fuel consumption figure should be normal? My owner's manual very much says otherwise. My manual says at a constant 120km/h (a speed I can't actually do where I live without getting fined off the Earth and having the car impounded for a month by the authorities) it will return 9.9 l/100. Well, I can do 100km/h and at that speed I saw 9.6 l/100. Pretty close I think considering my car is 26 years old and has done the best part of 240,000km so far. On an ill-defined 'urban driving cycle' my car is supposed to return 17.5 l/100km. I've never seen consumption that high before not even while towing a trailer from the hardware store around the suburbs. Suburban speed limits here are 50km/h and very strictly enforced by robo-cameras everywhere. The average of 120km/h highway driving and the urban cycle that gives you 17.5 l/100 consumption is supposed to be 11.9 l/100. Well I can't do 120km'h anywhere here, ever, under any circumstances because I live in a totalitarian police-state where cars are the enemy to be crushed by ever higher taxes and draconian legislation, but by the same token I can't reproduce a consumption figure of 17.5 l/100 either with my drivng style around the suburbs. My real world average is working out on the new chip being 12.6 l/100, down from 13.8 l/100 on the stock OE chip with the active DFCO.

I think 12.6 vs 11.9 considering all the above is close enough to not indicate that my car is set-up poorly or out of spec. Keep in mind too that the only mod from stock on my car is very heavy 16" E38 wheels with Continental SSR tyres which Continental themselves publish as being 25% heavier than their non-SSR equivalents. So not only are my wheels significantly heavier and larger than the stock fitments (higher rotational inertia) the owner's manual numbers were calculated with, but the tyres are also heavier to such a degree that you can consider my car is actually having to accelerate+brake effectively 5 of them instead of four. On top of this is the fact that my wheel's rolling diameter is larger by 3mm too (Ø651mm stock 15" style 5's vs Ø654mm on Style 61 wheels). This means my car should be producing higher than published fuel consumption figures anyway. The fact it is only doing so very marginally is remarkable.
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: SSSquid Tuning custom M30B34 chip about to install

Post by Brucey »

if you are seeing single figures from that V8 it can't be too bad.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Post Reply