Engine running woes

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Candycj1
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Engine running woes

Post by Candycj1 »

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...
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James
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635sharknose
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Re: Engine running woes

Post by 635sharknose »

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 »

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 »

Sent you a PM Candy

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Candycj1
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Re: Engine running woes

Post by Candycj1 »

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 »

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

Ralph
Thanks Ralph - seen and replied.
Cheers
James
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Re: Engine running woes

Post by Candycj1 »

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 »

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

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635sharknose
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Re: Engine running woes

Post by 635sharknose »

I can recommend a combination of Kontakt Chemie 60, 61 and WL. Perfect set for cleaning contacts.
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Candycj1
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Re: Engine running woes

Post by Candycj1 »

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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Re: Engine running woes

Post by 86_6series »

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.
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Candycj1
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Re: Engine running woes

Post by Candycj1 »

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
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Re: Engine running woes

Post by Candycj1 »

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...
Candycj1
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Re: Engine running woes

Post by Candycj1 »

Fitted replacement TPS courtesy of Ralph in SoCal - seems to run a *little* better but not a massive difference. Noticed whilst in there that the ICV on mine isn't the correct one for our cars - its a Bosch part # 0280140502 which a google search suggests is used on some Saab, Opel and even Yugo models but not the E24 as far as i can tell. Swapped that out with a used item (cleaned it thoroughly beforehand) and again seemed a *little* better but still not idling properly, will stall after 10-15 seconds if no throttle applied; can be kept alive if the throttle is feathered but very rough (to the point that in don't want to keep it going like that).

New video uploaded https://vimeo.com/553928687.

It does seem that there isn't the strong fuel smell after running now so am thinking this is maybe fuel starvation or intermittent ignition issue, despite having all new pump(s), filter, lines, tank and regulator, plugs, leads, coil, rotor & cap. Any suggestions on next test(s) to run? Fuel pressure? Fuel delivery? Spark test maybe?

Slightly concerned about trying a smoke test in the car park for fear of setting off the fire alarm (!!). I did go so far as to connect up a plastic drinks bottle + hose to the inlet behind the AFM ready for smoking - blowing in to this its very noticeable that pressure builds up and air blows back when pressure released - suggest to me no major leaks anywhere? I checked the 3 vacuum lines on the manifold, one for the FPR (seems fine), one for the cabin temp sensor (seems fine) and a 3rd that goes to the tube between the AFM and the throttle body (hose seems fine - curious what the point of this one is though?).
Last edited by Candycj1 on Sun May 23, 2021 2:21 pm, edited 1 time in total.
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635sharknose
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Re: Engine running woes

Post by 635sharknose »

Perhaps it's not one of these part that's bad but a dirty connector or broken cable.
I would continuity test all the cables back to the CPU to make sure.
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Candycj1
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Re: Engine running woes

Post by Candycj1 »

635sharknose wrote: Sun May 23, 2021 2:14 pm Perhaps it's not one of these part that's bad but a dirty connector or broken cable.
I would continuity test all the cables back to the CPU to make sure.
Good thought Paul - presumably if that's the case i could disconnect a badly connected part and not see any difference in running too?
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635sharknose
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Re: Engine running woes

Post by 635sharknose »

Candycj1 wrote: Sun May 23, 2021 2:23 pm presumably if that's the case i could disconnect a badly connected part and not see any difference in running too?
If you are 100% sure that the part itself is working properly, that could work.
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Re: Engine running woes

Post by hornhospital »

Your observation that it seems to be running lean once again points to vacuum leak(s). Doing a smoke test to find it/them will eliminate that as a cause, but I believe you'll find the problem is just that, a vacuum leak. I've seen it too many times on my own and other's vehicles to believe it's anything else.
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Re: Engine running woes

Post by bpoliakoff »

Pull the dipstick while running. If it makes no difference in the idle, you have a vacuum leak
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Re: Engine running woes

Post by Steve M6 »

I get that you have a new fuel pressure regulator. I would put a pressure gauge on the fuel rail line just to make sure fuel pressure is not the issue.
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Ralph in Socal
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Re: Engine running woes

Post by Ralph in Socal »

Pic of the B35 TPS pin connector. Hopefully numbering is legible

#1-3 are for the potentiometer. I’m able to get resistance readings between #1 and #3 around 70k ohms at idle and down to 3400 ohms at WOT. Seemed like a linear change as the throttle is opened. Also get readings from other combinations so it’s a good indication the potentiometer is working.

At Idle, #4 and #6 are open circuit. Test this continuously to make sure the circuit opens and closes as necessary. Test on slow return to idle as the switch may not trigger on a “soft return”.

At WOT #4 and #5 are open circuit. This should also be tested continuously throughout the throttle opening process. I have one that doesn’t always trigger at WOT.

All tests with engine off and connector off the TPS. Can’t damage anything when it’s not connected 😊. Good luck

Ralph
916C6219-D0A5-4F2F-9866-8621B770EFFE.jpeg
916C6219-D0A5-4F2F-9866-8621B770EFFE.jpeg (345.67 KiB) Viewed 6976 times
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)
Candycj1
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Re: Engine running woes

Post by Candycj1 »

hornhospital wrote: Sun May 23, 2021 7:12 pm Your observation that it seems to be running lean once again points to vacuum leak(s). Doing a smoke test to find it/them will eliminate that as a cause, but I believe you'll find the problem is just that, a vacuum leak. I've seen it too many times on my own and other's vehicles to believe it's anything else.
Thanks Ken; agree it does seem like a vacuum issue though all the hoses are new and nice and secure - smoke test the only way to tell i guess. Am away this week but will have a look again this weekend and see if i can do the smoke test in the car park without setting off the alarm :D - if not i'll need to get it towed outside and do it there.
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Re: Engine running woes

Post by Candycj1 »

bpoliakoff wrote: Sun May 23, 2021 7:57 pm Pull the dipstick while running. If it makes no difference in the idle, you have a vacuum leak
Thanks Bert - tried that and it didn't seem to get any worse but that said it was so rough beforehand it was hard to tell! Are there any common places for leaks on the B35 *other* than the vacuum hoses, dipstick and filler cap?
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Re: Engine running woes

Post by Candycj1 »

Steve M6 wrote: Mon May 24, 2021 7:33 pm I get that you have a new fuel pressure regulator. I would put a pressure gauge on the fuel rail line just to make sure fuel pressure is not the issue.
Yes that was one of my thoughts - made the mistake though of buying a cheap pressure tester on amazon that leaked everywhere tho i did get a reading of ~30psi before shutting it off for fear of starting a fire. Will need to get a better one to do a reliable test...
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Re: Engine running woes

Post by Candycj1 »

Ralph in Socal wrote: Tue May 25, 2021 11:10 pm Pic of the B35 TPS pin connector. Hopefully numbering is legible

#1-3 are for the potentiometer. I’m able to get resistance readings between #1 and #3 around 70k ohms at idle and down to 3400 ohms at WOT. Seemed like a linear change as the throttle is opened. Also get readings from other combinations so it’s a good indication the potentiometer is working.

At Idle, #4 and #6 are open circuit. Test this continuously to make sure the circuit opens and closes as necessary. Test on slow return to idle as the switch may not trigger on a “soft return”.

At WOT #4 and #5 are open circuit. This should also be tested continuously throughout the throttle opening process. I have one that doesn’t always trigger at WOT.

All tests with engine off and connector off the TPS. Can’t damage anything when it’s not connected 😊. Good luck

Ralph
916C6219-D0A5-4F2F-9866-8621B770EFFE.jpeg
That's really helpful Ralph, many thanks - will definitely do this for both the one you sent me and my original - worst case they're both fine and i have a working spare.
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