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Engine running woes

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Candycj1
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Engine running woes

Post by Candycj1 » Mon May 03, 2021 11:08 am

Hi all

Need some help please - still struggling to get my car running properly. Has had an intermittent fault since i got it ~2 years ago; one day it would be fine, the next it would stutter, stall, reek of fuel and barely go round the block. Over the ensuing 18 mths its had a new fuel tank, new FPR, new AFM, new boot between AFM & throttle body, new CTS, oil & coolant flush / fill, new plugs and throttle body & ICV cleaned. Some bits of work seemed to help but as the issue was intermittent it was hard to tell - either way it always came back soon after.

The running issue got much worse around November, at which point it crawled into the secure underground car park where it normally stays over winter. I've done what work i can to it over winter whilst in this facility (which again is a public car park, not a garage), specifically:

- new distributor cap & rotor
- new coil
- new leads (which on the B35 includes the pulse sensor)
- new crank sensor
- new fuel lines & hoses
- new main fuel pump & filter
- in-tank pump refurbished (bayonet style are NLA so new pump / filter fitted to existing hanger from a US-style bolt down unit)
- new main and fuel pump relay
- 079 ECU checked (original one diagnosed with faults & repaired, my spare was diagnosed fine though so that's on the car now)
- 3* vacuum lines from manifold checked (one to the FPR, one to the cabin temp sensor and the 3rd to the intake boot)

The new bits are all OEM where still available. I also did a compression test - all 6 showed between 185 and 200 (i was pretty surprised at how high they were).

To fit the fuel lines without dropping the rear subframe, diff or even the prop i also had to remove & replace the brake lines, hoses and clips - though these were in need of replacing anyway. With issues getting parts during lockdown and only having a couple of hours each weekend to tinker in a car park its taken a long time to get everything back together but its all back in place now - though to my dismay the issue is pretty much the same.

I've uploaded a video here to show what happens when starting - https://vimeo.com/544502891. It fires up no problem at all but then runs erratically, hunts a little and stalls. If i keep the revs up it will keep running but feels like its missing and / or running a completely wrong mixture - strong fuel smell after running.

Thoughts? I've not put a fuel pressure gauge over it tho as above everything from the tank to the FPR is new - could this be sticking / leaking injectors? The only sensor that's not been replaced is the TPS - mine is the 6-pin version (0280120406) as its a highline / B35 engine, i'm not sure if its still available - would a failing TPS cause this behaviour? I've not done a smoke test - as mentioned this is a car park, not a garage so i'm a bit stuck for facilities - are these vacuum leak symptoms? Though i've changed the plugs, leads, cap, rotor and coil, the HT lead from coil to cap is the original - i guess an intermittent spark from this lead could cause problems, anyone know the part number?

Appreciate any help or advice...
Cheers
James

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635sharknose
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Re: Engine running woes

Post by 635sharknose » Mon May 03, 2021 3:27 pm

My first guess is a bad or dirty idle control valve, or perhaps the connector on this valve is bad.
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sideshowbob
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Re: Engine running woes

Post by sideshowbob » Mon May 03, 2021 4:33 pm

I would definitely have a go at replacing the throttle position sensor.

My car recently had a similar problem, although I could get it to drive, but it would then cut out and almost instantly restart.

The Throttle position sensor is connected to the idle control valve so as the TPS fails it triggers the idle control valve and in my case as you were driving along you got a loss of power resulting in either a stall or the engine going into an erratic idle.

Initially it was thought to be the crankshaft sensor but after replacing it and checking out and cleaning the AFM by a system of elimination the TPS turned out to have an intermitant fault.

Not sure if this helps.

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Ralph in Socal
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Re: Engine running woes

Post by Ralph in Socal » Mon May 03, 2021 5:07 pm

Sent you a PM Candy

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
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81 528i Kastanien 5-speed
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Candycj1
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Re: Engine running woes

Post by Candycj1 » Mon May 03, 2021 10:41 pm

635sharknose wrote:
Mon May 03, 2021 3:27 pm
My first guess is a bad or dirty idle control valve, or perhaps the connector on this valve is bad.
Thanks Paul - I did clean it out and heard the distinctive clicking of the inner mechanism moving freely after cleaning and the connectors look in good shape - I should probably run a meter over it plus all the other connectors where they come into the ecu though...

Candycj1
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Re: Engine running woes

Post by Candycj1 » Mon May 03, 2021 10:41 pm

Ralph in Socal wrote:
Mon May 03, 2021 5:07 pm
Sent you a PM Candy

Ralph
Thanks Ralph - seen and replied.
Cheers
James

Candycj1
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Re: Engine running woes

Post by Candycj1 » Mon May 03, 2021 10:49 pm

sideshowbob wrote:
Mon May 03, 2021 4:33 pm
I would definitely have a go at replacing the throttle position sensor.

My car recently had a similar problem, although I could get it to drive, but it would then cut out and almost instantly restart.

The Throttle position sensor is connected to the idle control valve so as the TPS fails it triggers the idle control valve and in my case as you were driving along you got a loss of power resulting in either a stall or the engine going into an erratic idle.

Initially it was thought to be the crankshaft sensor but after replacing it and checking out and cleaning the AFM by a system of elimination the TPS turned out to have an intermitant fault.

Not sure if this helps.
Thanks sideshowbob - yes I'd seen your post and it did sound similar to what I'm seeing - also I've replaced just about everything else 🙄. Will give the TPS change a go and see how that pans out - fingers crossed...

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Ralph in Socal
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Re: Engine running woes

Post by Ralph in Socal » Tue May 04, 2021 12:47 am

Because it is an electrical switch, corrosion of the internal contacts would be your likely issue. Take the tps off and spray contact lubricant/cleaner in the hole. Hopefully it penetrates and provides some help. Good luck

Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)

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635sharknose
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Re: Engine running woes

Post by 635sharknose » Tue May 04, 2021 5:43 am

I can recommend a combination of Kontakt Chemie 60, 61 and WL. Perfect set for cleaning contacts.
Paul
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1987 635CSi Bronzitbeige

Candycj1
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Re: Engine running woes

Post by Candycj1 » Tue May 04, 2021 8:47 am

635sharknose wrote:
Tue May 04, 2021 5:43 am
I can recommend a combination of Kontakt Chemie 60, 61 and WL. Perfect set for cleaning contacts.
Thanks Paul & Ralph - will be round the car park later with a can of contact cleaner...

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86_6series
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Re: Engine running woes

Post by 86_6series » Tue May 04, 2021 1:17 pm

I have an easy way to do a smoke test even in your underground.

Purchase a bee smoker:
https://www.bing.com/search?q=bee+smoke ... HRDEF&sp=1

Use an empty plastic soda bottle and tape a small hose to spout of smoker
and the top of the bottle. Cut the bottom of the bottle and tape to end of rubber boot
#6.
https://www.realoem.com/bmw/enUS/showpa ... Id=13_0262.

Load the smoker with your choice of smoke chips, light the chips and pump the smoke thru the system.

Works for me every time, also not an expensive solution.

Good luck.

Candycj1
Bigcoupe 100 Post club
Posts: 120
Joined: Thu May 17, 2018 10:22 pm
Location: London

Re: Engine running woes

Post by Candycj1 » Tue May 04, 2021 3:38 pm

86_6series wrote:
Tue May 04, 2021 1:17 pm
I have an easy way to do a smoke test even in your underground.

Purchase a bee smoker:
https://www.bing.com/search?q=bee+smoke ... HRDEF&sp=1

Use an empty plastic soda bottle and tape a small hose to spout of smoker
and the top of the bottle. Cut the bottom of the bottle and tape to end of rubber boot
#6.
https://www.realoem.com/bmw/enUS/showpa ... Id=13_0262.

Load the smoker with your choice of smoke chips, light the chips and pump the smoke thru the system.

Works for me every time, also not an expensive solution.

Good luck.
Nice solution, i may just try that after the TPS clean-up! Will need to do it very early in the morning - i get funny looks from the security guy as it is when he finds me under the car with bits of the fuel supply lying around the car park, though after initially telling me "you're not really supposed to do that here" he now usually just asks "not given up yet then?"...

Candycj1
Bigcoupe 100 Post club
Posts: 120
Joined: Thu May 17, 2018 10:22 pm
Location: London

Re: Engine running woes

Post by Candycj1 » Fri May 07, 2021 1:29 pm

Finally got round to going to the garage, removing and spraying contact cleaner into the TPS and refitting - sadly no difference; of course doesn't mean its not the cause, just that i now need to get a known working one to verify. Hopefully Ralph will sort me out here, meantime i'll look at buying myself a bee smoker...

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