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Fritz chip for M88/3: what does it do?

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wattsmonkey
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Fritz chip for M88/3: what does it do?

Post by wattsmonkey » Mon Sep 03, 2018 6:05 pm

Apologies if this is covered already, GazM3's excellent posts touch upon it I know.

I understand the rev limit is raised, but Fritz told me the afm will need adjusting to ensure sufficient fuelling. This makes me a bit nervous as I realise I don't know any of the details.

If anyone could chip in I'd be grateful.

Cheers,

Rob
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Re: Fritz chip for M88/3: what does it do?

Post by ron » Mon Sep 03, 2018 6:18 pm

wattsmonkey wrote:
Mon Sep 03, 2018 6:05 pm

.....If anyone could chip in I'd be grateful.
Very clever.
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wattsmonkey
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Re: Fritz chip for M88/3: what does it do?

Post by wattsmonkey » Mon Sep 03, 2018 6:30 pm

Ha! "chip in"!
"Most of it necessary; all of it enjoyable[!]" LJKS
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Re: Fritz chip for M88/3: what does it do?

Post by wattsmonkey » Mon Sep 03, 2018 6:30 pm

Sorry Ron,

I got my own joke after you!
"Most of it necessary; all of it enjoyable[!]" LJKS
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Re: Fritz chip for M88/3: what does it do?

Post by sharkfan » Mon Sep 03, 2018 7:54 pm

I'm not sure about any AFM changes but I recall reading the details of the Hartge conversion of the M635 and IIRC all that seemed to do was the rev limiter to extract more power, meaning there was little or no extra power to be gained across the rev range below the extended rev limit... which doesn't seem an entirely clever thing to do to now near forty year old engines.
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Re: Fritz chip for M88/3: what does it do?

Post by Brucey » Wed Sep 05, 2018 11:43 pm

the chip will have been developed using just one or two engines. The change in the redline is obvious and (like Sharkfan says) not necessarily a good idea on an old engine. I'd want the engine to be in top condition and I'd probably want a new (higher rated) crank pulley hub too. Whether the other (non obvious) changes to timing and fuelling are

a) taking up the tolerance in that is built into all systems of this type or
b) taking out an artificial restriction that BMW programmed in or
c) specific/particular to the development engines only or
d) making better use of modern fuel

I leave to your imagination. Given that RHD M635s are a bit down on power vs LHD ones I doubt that it is b) in the case of RHD M635s; although there may be improvements to be made I really think that the exhaust manifold is holding the engine back.

c) is a bit more of a worry; if any of the development engines had slightly anomalous parts in it (valve timing, AFM / injector calibration etc) then the chip might be worth nothing on another engine or will only work if the setup is exactly duplicated, which means no switching back to the standard chip....

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Re: Fritz chip for M88/3: what does it do?

Post by wattsmonkey » Thu Sep 06, 2018 2:52 pm

Thanks all. I think I'll leave it in the box.
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Re: Fritz chip for M88/3: what does it do?

Post by GazM3 » Thu Sep 06, 2018 8:39 pm

It’s a hard one to quantify. As I have the fritz headers the chip seemed to improve engine response slighly and rpm limit is around 7150 not the 7500. As Brucey states spinning an old engine especially one with a known weakness like the crank hub is a little risky.

If one was to replace the crank hub and with an upgraded dual timing chain can’t see why you couldn’t rev it to 7500 every day.

I’ve got a feeling the m88/3 is massively conservatively mapped from the factory. If I ever stop playing with my other cars and get to the e24, I’ll wire in the standalone and find out.
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Brucey
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Re: Fritz chip for M88/3: what does it do?

Post by Brucey » Thu Sep 06, 2018 11:55 pm

I think the engine is conservatively tuned but it may not be conservatively mapped per se. With the right exhaust manifold fitted (to RHD spec and US spec cars) and a few other changes there is plenty of power there but the biggest change you can make is probably in the camshafts; that an engine of this type makes some torque at low rpm is a pretty good sign that the valve timing/duration is nothing like optimised for high rpms and max power. However most changes to the camshafts you can make will render the engine less friendly on the street (in normal driving) too.

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Re: Fritz chip for M88/3: what does it do?

Post by DRPM635CSi » Fri Sep 21, 2018 3:02 pm

wattsmonkey wrote:
Mon Sep 03, 2018 6:05 pm
Apologies if this is covered already, GazM3's excellent posts touch upon it I know.

I understand the rev limit is raised, but Fritz told me the afm will need adjusting to ensure sufficient fuelling.
When I heard this from Rich it made me nervous too. Really and truly, this should not be necessary if the chip has been programmed properly for the engine in the first place. It sounds like a derivation of a racing chip de-tuned for street use to me, rather than a ground up tuned chip for street use from first principals. If that's the case, then it's a compromised chip and not ideal.

I went with a SSSquid chip instead that nullifies the DFCO injector cut-off to make coasting to red traffic lights much smoother and makes on/off throttle transitions much easier and without the kangaroo hopping driveline snatching. Because I like flying under the radar allied to some dignity and refinement and detest look-at-me displays of pointless boy-racer exhibitionism, my chip also does away with the engine braking ignition timing advance on overrun that causes the 'boom, boom boom' exhaust burble on the closed throttle overrun as well.

This not only makes the exhaust quieter, but also saves wear and tear on the pistons and engine internals, as well as making the throttle transitions off/on/off in stop start traffic much more liveable with everyday. Of course the chip is also tuned for 98RON fuel and makes the thing go like a shower of sh!t too, when you want to get on it.

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