Help with poorly running engine

[minesapint]

My 1986 325i Cab 20600 mls has just come out of hibernation after sitting in the garage for many years.
Passed MOT, no advisories, engine been running for about 4 hrs, whilst working on it in garage, no probs. The MOT guy adjusted the AFM to get required exhaust emissions, said he couldn't get it exact & left a little rich.
But now out on road it keeps losing power & dies away as though theres a fuel problem, it stutters as the speed drops off & (after possibly 20 secs of heart stopping engine surging/stalling) eventually clears itself & of we go again. This seems to happen after trying to take the revs above 2000, the rev counter is not operating smoothly at these speeds & goes in jerks, the fuel gauge is also temperamental & shows a reading then slowly returns to zero.
I have not changed the fuel filter & did have a problem with the fuel pump, which I repaired. As the fuel comes out of the pump it passes through a non-return valve, (to maintain the high pressure in the fuel rail after engine shut down, called a damper on the parts list) ...any known problems with this?
It feels fuel related &/or electronics.
Has anybody any thoughts as to what this may be, without suggesting I start changing parts wholesale.
Cheers

[Speedtouch]

Did you leave stale fuel in the tank when it was left parked up? It would be a good idea to change the fuel filter.

[jimbom30cab]

Have you checked out your DME relay?

[minesapint]

Did you leave stale fuel in the tank when it was left parked up? It would be a good idea to change the fuel filter.

Yes v small amount of fuel was left in the tank (leaded, yes that long ago!) but have since put in about seven gallons of unleaded (contacted BMW tech Germany, who said could run on unleaded, all cars after Sep 84 have hardened valve seats)
Ordered fuel filter.
Thanks so far
Cheers

[Speedtouch]

Probably just needs a good long run to clear out the cobwebs...

[minesapint]

Have you checked out your DME relay?

No have not checked DME as such.
As said engine has run at tick-over for around four hrs, without a hick-up & has started each & every time on first turn off key.
Do you suspect some thing could be happening at speed with DME relay?
Thanks so far
Cheers

[Speedtouch]

Also check the blue temperature sensor:

http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

[minesapint]

Probably just needs a good long run to clear out the cobwebs...

These were my thoughts yesterday, which was the first "day on the road". After 30 mins running on the motorway I slowly increased speed, 3000rpm+, around 75/80mph then it happened, limped home.
Today had a very steady run at 2000rpm for about 25 mls, a little faster towards the end, maybe 2500rpm, happened again, very disconcerting as the engine goes extremely lumpy, the engine actually stopped running this time, but after a few starts fired up as normal, fortunately only a couple of miles from home.
Very sad as brought the car out of hibernation at the request of my son to take him to his school Prom in, which is tonight! unsure whether to risk it. Have been working on the car for 4/5 weeks, & all was looking so good. Especially the car!
Cheers

[Speedtouch]

Try disconnecting the battery or ECU and leaving it for an hour or so to reset the ECU. Let it idle for at least 10 minutes to enable base idle settings to be learnt, switch off, then take it for a drive throughout the rev range.

This ensures full data transfer from the EPROM chip to the processor.

[minesapint]

Also check the blue temperature sensor:

http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

Just checked the blue temp sensor. Engine warmish.......1006 ohms, left a few minutes checked again.......1020 ohms, this looks within the range on Wiki & increasing as cooling.
Cheers

[minesapint]

Try disconnecting the battery or ECU and leaving it for an hour or so to reset the ECU. Let it idle for at least 10 minutes to enable base idle settings to be learnt, switch off, then take it for a drive throughout the rev range.

This ensures full data transfer from the EPROM chip to the processor.

Ok battery disconnected, I'll let you know.

Come on guys! someone must know, got to sort it for tonight, my son's spent £200 on new clothes for his Prom so he'll be as smart as the car!

Cheers so far.

[minesapint]

Try disconnecting the battery or ECU and leaving it for an hour or so to reset the ECU. Let it idle for at least 10 minutes to enable base idle settings to be learnt, switch off, then take it for a drive throughout the rev range.

This ensures full data transfer from the EPROM chip to the processor.

Ok battery disconnected, I'll let you know.

Come on guys! someone must know, got to sort it for tonight, my son's spent £200 on new clothes for his Prom so he'll be as smart as the car!

Cheers so far.

All back together, followed instructions to the letter! Unsure whether anything changed as don't want to push revs too high as going to risk the journey tonight.
Still feel in "my water" it's fuel related.
I'll let you know
Cheers

[minesapint]

Well got him there, with a few stuttery moments, so problem unresolved.
Anyone able to contribute, wouldn't have thought this would outwit all you guys, come on who knows the answer?

[Mitchen]

Can't help but glad you got him there.. he'd never live down a breakdown outside the school in front of his boys and his prom date

[daimlerman]

You say that the MoT man adjusted the AFM to get emissions passable?

My M20 engined E30 failed on emissions time before last,just needed it's spark plugs cleaning and gapping correctly....

[Grrrmachine]

It hasn't outwitted us at all, but there are lots of questions aksed that you haven't answered, so we can't procede from there.

Have you changed the fuel filter? Hae you tested the resistance of the blue temp sensor at the ECU, both hot and cold? Have you checked all the rubber intake hoses (incl. the rubber plug under the throttle body) for air leaks? Have you removed and inspected the spark plugs, checked the HT leads for cracks, and removed the dizzy cap and rotor to check their condition? All of these should be par for the course before even firing up a car that's been stood for years, let alone driving it anywhere.

[Brianmoooore]

The MOT guy adjusted the AFM to get required exhaust emissions,

Why do so called mechanics do this???? This needs to go back to exactly where it was when it left the factory. It only has one correct setting, and if that setting gives incorrect results, then that is because of faults that need to be fixed.

What does the tacho. do when the problem occurs? Drop with the engine revs., or drop rapidly?

[Speedtouch]

Sounds like it could be a loose electrical connection. Start by checking the engine-to-body earth strap is secure.

[minesapint]

It hasn't outwitted us at all, but there are lots of questions aksed that you haven't answered, so we can't procede from there.

Have you changed the fuel filter? Hae you tested the resistance of the blue temp sensor at the ECU, both hot and cold? Have you checked all the rubber intake hoses (incl. the rubber plug under the throttle body) for air leaks? Have you removed and inspected the spark plugs, checked the HT leads for cracks, and removed the dizzy cap and rotor to check their condition? All of these should be par for the course before even firing up a car that's been stood for years, let alone driving it anywhere.

Yes all good points. I'll answer them in order.
i) I did not change the fuel filter, but I have now. I back flushed the old one & very little came out, a fine dust like substance settled in about 200ml of fuel. (Coincidently, BMW do not now change the fuel filters on their unleaded petrol engined cars, in fact they didn't even have one in stock!)
ii) Yes have tested blue sensor & as spec.
iii) Yes all hoses checked before start up, found the ICV to throttle body had the start of a crack, replaced with new one.
iv) Yes all HT leads, distributor & rotor checked & cleaned whilst timing belt replaced, all very good condition. Spark plugs removed regapped etc, had only done 2000mls with them, now replaced with new.

Before I changed the filter today, I disconnected the hose from the rail side of the filter, bridged the relay & measured the fuel flow rate, 300ml in 10 secs, don't see a problem with that.
I then put it back & disconnected the hose back to tank from the FPR, gain bridged relay & measured the flow coming through the old filter, fuel rail & FPR, about the same, ie a good flow rate.
I then changed the filter & did the same again, very similar results.

Thank you for asking, if you feel there's anything else I've not answered just ask, the more minds on this the better.
Thank you & Cheers

[Speedtouch]

Yes all good points. I'll answer them in order.
i) I did not change the fuel filter, but I have now. I back flushed the old one & very little came out, a fine dust like substance settled in about 200ml of fuel. (Coincidently, BMW do not now change the fuel filters on their unleaded petrol engined cars, in fact they didn't even have one in stock!)

That's probably because modern BMW engines don't seem to last very long, if the numerous tales of woe regarding the M52, N47, etc. engines are anything to go by...

[minesapint]

The MOT guy adjusted the AFM to get required exhaust emissions,

Why do so called mechanics do this???? This needs to go back to exactly where it was when it left the factory. It only has one correct setting, and if that setting gives incorrect results, then that is because of faults that need to be fixed.

What does the tacho. do when the problem occurs? Drop with the engine revs., or drop rapidly?

Good point, I guess it's his way of getting the emissions to target, I'll go back & speak with him, my local garage & always been a good bloke, I'll see if it can go to original set point, he will know what that was before he adjusted it.

The tacho drops with engine revs, although it's not a particularly smooth movement, a tiny bit "jerky" I'd say. (when the fault occurs)

Fuel gauge still doing it's own thing, not sure this is related though. The only instrument not working as it should.

After completing this work today I've gone for a run, about 20 mls & driven the car hard, a very slight hesitation for maybe 10 secs about half way round, feels like bad fuel.

Thanks for your help, any more ideas welcome, I'm trying to source the fault without throwing the parts department at it.

Thank you & Cheers

[minesapint]

Some pictures of the car coming out of hibernation









I bought it Aug 86, one of the first RHD ones produced.
Cheers

[minesapint]

Update:

I also took the CPS from it's holder, cleaned it checked the connections & cable, then replaced it ensuring it was positioned correctly in it's holder/bracket.

[Grrrmachine]

bloody hell that's clean Lovely motor you have there.

It's always worth sending the injectors off to be rebuilt (10 quid each with Injectortune in the Trader's section) as it may be that one or more is sticking, which is why it can't handle high revs.

If you've got an assistant who can hold the accelerator pedal, then using a screwdriver as a stethoscope should help you confirm whether each injector is firing or not.

[minesapint]

bloody hell that's clean Lovely motor you have there.

It's always worth sending the injectors off to be rebuilt (10 quid each with Injectortune in the Trader's section) as it may be that one or more is sticking, which is why it can't handle high revs.

If you've got an assistant who can hold the accelerator pedal, then using a screwdriver as a stethoscope should help you confirm whether each injector is firing or not.

Thanks it is rather nice, in superb condition (apart from a slight misfire!!!) & totally original.

I've been thinking about the injectors, have done the "screwdriver test" the other day & they all appear to be firing, although that is no test for flow & spray pattern. It looks an awful job to take the inlet manifold off, is it possible to get the injectors out with the manifold in position? Haynes shows it with the manifold off.
Thanks for your time
Cheers

[Brianmoooore]

The tacho drops with engine revs, although it's not a particularly smooth movement, a tiny bit "jerky" I'd say. (when the fault occurs)

Fuel gauge still doing it's own thing, not sure this is related though.

That eliminates the the crank sensor, a fair chunk of processing electronics, and the power feeds to said electronics.
I see you still haven't checked the DME relay, which could be interrupting the power to the injectors. You can test this by removing the relay and using wire links to link together pin 30 and both pin 87s of its socket. Don't forget to remove the links when you stop the engine.
Fuel gauge is nothing to do with your problem, unless there's a problem with the common earth point for the level sender and fuel pump, which is on the LH side of the rear seat pan.

[minesapint]

I see you still haven't checked the DME relay, which could be interrupting the power to the injectors.

Ok thanks, I'll check this out tomorrow.

I've done over 100 mls + several hours running in garage, so tomorrow I'm going to drop the oil & refill with Fuchs Titan Super Syn 5W-40 the postman brought today, this was a recommendation of "oilman" on here & the oil I've decided to use in all my cars, it looks so good I could put it on my toast for breakfast!

To add: whilst messing this afternoon, with the engine running I disconnected the vacuum pipe from manifold to FPR, revs went up maybe 100, as they should I think.

Many thanks again

[age]

I don't see why you are still looking for answers. Brian moore has answered your question. The afm is at fault. I'd bet my e30 on it.

[minesapint]

The MOT guy adjusted the AFM to get required exhaust emissions,

Why do so called mechanics do this???? This needs to go back to exactly where it was when it left the factory. It only has one correct setting, and if that setting gives incorrect results, then that is because of faults that need to be fixed.

What does the tacho. do when the problem occurs? Drop with the engine revs., or drop rapidly?

So I'm absolutely sure here, the adjustment Alan screw on AFM is for enriching or weakening the mixture at idle ONLY. (By adjusting the amount of air).
This will have no/measurable effect when the engine is at speed, when a much greater volume of air is passing through the AFM via the main airway.
Thanks & cheers
PS injectors removal with inlet manifold on car. Can anyone answer this.

[Brianmoooore]

PS injectors removal with inlet manifold on car. Can anyone answer this.

Yes, manifold on car.

[Speedtouch]

I would try running some injector cleaner or Redex through it first, before attempting to remove the injectors.

[Brianmoooore]

Someone mention snake oil?

[Speedtouch]

Worth a try, surely, before going to all the hassle of removing injectors and sending them away...

Don't forget, this is a 20,000-mile car - the injectors are unlikely to be worn.