Stall & die or runs on 5 cylinders help please

Post Sat Oct 10, 2015 12:03 am

I have a 325is '89
Been doing tons of work on it to get it back on the road after nearly 3yrs. Done 195K

Symptoms :
Car starts and runs but will:
1) die while driving but auto bumps starts -can can work fine for a mile then stutter for another one - about 5-7 die/'bump start' moments, or can run for miles in stutter mode or runs fine!
2) it can also decide to only run on (I think) 5 cylinders and that can then 'clear' or as of tonight go on for mile after mile!

During this experience you get a lot of vibration through the steering wheel - perhaps not unexpectedly!
3) inbetween this bad running times, it runs sweet and fine and totally responsive

Diagnosis :
Found that if I wobble (push away then towards me - at right angles to it), the injector wiring bar, it did 4 x make the engine die or stutter. However it isn't completely consistent.
That made me wonder about a wiring fault but without being consistent I'm not totally convinced.
(I called BMW parts and they said that there is an injector valve plug so I wonder if it might be that ?)
There's no consistency with speed or throttle opening.

Sometime when I have applied power there can be NO response whatsoever, this tends to be around 2k revs, speed around 40,ph and the way to resolve this is to re-start the car to get the throttle operational.
This also happens regularly.

The coolant gauge only works from time to time.
I have eventually purchased a new coolant sensor.
I did various tests to the old one and it failed to work ... however and embarrassingly I then realised that I'd tested the wrong one!

D'Oh!
I had also swapped out the gauge with other instrument panels in case that got it to work, but everything failed. (I have noticed that the right instrument panel light doesn't work and wondered if that side of the board was dead, but swapped out instrument panels and nothing changed, so I think that's just a red herring!
However sometimes :
the needle flickers all over the place,
or it actually shows a reading,
or as more likely it now, just flickers wildly near the lower end of the gauge
or fails to work at all.

Recent new components (topical)
Spark plugs
Thermostat
Rotor arm and diz cap.
Appears to have good ht leads and have swapped out the ignition coil & it's lead (separately), to no avail, swapped them back (1x1).
Head done 6k miles ago.

I'm totally stuck. I've looked in my R Bentley's workshop manual and it doesn't seem to cover these symptoms.
Any suggestions or ideas what might be wrong, would be most gratefully received.

I hope to travel nearly 700miles next weekend! and I need the car working!

Post Sat Oct 10, 2015 9:18 am

Note that although the pins are likely to be corroded, the main area of the problem is under the rubber boot of the lower half of the plug and socket, where you're likely to find wires corroded through. The corrosion will also have travelled up the wires, under the PVC insulation, making the copper difficult to solder to effect a repair.

Post Sun Oct 11, 2015 1:04 am

Thank you willnz & Brianmoooore for the advice.

I took off the plug and there is zero corrosion on any of the metal connections!

Then I took off the injector wire assembly and checked that all wires (in spite of wobbling) all retain a signal. All passed.
I then had another look at everything and the starter motor has a positive wire which does have a few cracks in the red outer sheath, but the wire looks ok. This warrants further checking to be sure!
I have images if you'd like to see them. (Can I place images on here directly?)
I then re-checked the air intake bellows (I know they fail frequently & last checked a few wks ago) & found a few (new) cracks, only one definitely allowing in air, so fixed it.

(temporarily with sealant).
Then I took the car on a test run and so far, it ran fine, but previously when the bellows were OK IIRC the 'stutter' problem was present!
So although I think this symptom is OK for the moment, I do think that the problem will be back perhaps with less severity or regularity, I hope!?
I just cannot believe that this and this alone, would be possible to have caused all the symptoms!
So I think (like a fuel pipe leak that developed) this is just a passing secondary issue.
The coolant gauge is still incorrect.
Thanks.

(edited for grammar)

Post Wed Oct 14, 2015 9:39 am

Well it's still running ok !
I'm hoping that this air intake duct is all that it (perhaps?) was.
Anyway ordered a new one as I know my repair is temporary.
Thanks for the help.

I am still concerned about the coolant gauge being intermittent though. With the wiring all connecting fine at the engine injector loom area, I wonder if there is any other particular area to check, that anyone knows of please?

I'll retry the electrical testing and see what that says.... any other ideas ?

Post Fri Oct 16, 2015 10:17 am

There is a well known and common coolant gauge fault caused by the small brass nut on the back of the instrument cluster that holds the gauge in place coming loose, but this usually results in a gauge that reads too high or a needle that jumps about.
Any E30 that has been laid up for a number of years without a battery connected is likely to require attention to the batteries on the SI board inside the instrument cluster. The resulting symptoms from these batteries being flat vary with the type of board fitted, but include temperature gauge problems.

Post Fri Oct 16, 2015 8:19 pm

Well the new air duct arrived and I fitted it. I'd had the car just slightly stutter this morning and also after I put in the new part.
There was a 'just possible' crack in the old one (again) but the new one is of course perfect.

So I'm back to worrying.
It was only very brief but it happened. It wasn't a real engine auto bump start more of a small hint of cut out. But it is low on fuel. I'll top it up tomorrow and see if it happens again.

I need to leave soon and this will delay things.
otherwise she's really sweet.

Post Mon Oct 19, 2015 1:41 am

Well sorry to say but the 'attempt to stall' is back like it was before. Really disheartening.
So, any thoughts ?

Post Mon Oct 19, 2015 10:06 am

Has the TPS been checked for functioning and correct adjustment?
Remember, like most 'adjustments' on your car, they were adjusted correctly at the factory, and are unlikely to have moved themselves, so don't actually adjust anything permanently, unless it's obvious it's already been 'got at', even if moving it appears to make an improvement.
Your OP says the car was running on five cylinders. This is barely noticeable on a M20, so I suspect it was more likely to be three of four cylinders.

Post Wed Oct 21, 2015 9:18 am

Well I managed to drive about 350miles but the last 3miles it got really bad stalling then stalled dead and refused to start about 3 times the worst taking about 8minutes with long pauses inbetween!

Hope to get some help today with a friend...

But any more thoughts please?

Post Wed Oct 21, 2015 10:30 am

Back to the C191 is my suggestion. Your problems fit problems here perfectly.

Post Wed Oct 21, 2015 10:49 pm

Not adjusted the TPS. But as the car can run fine for what now seems to be days, as sweet as pie would that not suggest that it is OK?
I don't want to change something and introduce a 'red herring'. I really want to find the cause.

However today with an engineer friend juggling wires we found that the group of wires to the rear of the engine bay by the firewall caused the car to stall 3 times reliably ! We believed that the wire failing it was the alarm system one. Having looked at the alarm (of which this was one of them) and the bad condition of the wiring we removed all the alarm system from every section of wiring loom carefully and painstakingly. Applying all sorts of metering tests as we went to ensure nothing was likely to misfunction once it was all removed.
Also checked the thermostat and sender switch inc ohms readings and they are all functioning just fine.
However it is now just not running.
The thought is now that maybe there is more than one wiring loom error or just something else ?

Until I can get it going only then can I know whats making it fail.
My friend is gutted that we've failed to solve it. Sadly he has to be away tomorrow so cannot give it more time.

Post Thu Oct 22, 2015 12:04 am

Alarm/immobilisers were never a standard fit on E30s, but were an expensive option, fitted by the dealer, or of course, could have been fitted at any time, by a DIY owner or independent alarm fitter.
Although BMW supplied detailed instructions of how to connect the BMW or the two 'approved' alarms to their new cars, not all dealers followed these instructions, so there can be loads of variations on how and where the immobilisers are connected.
This is the first time you've even mentioned the existence of an immobiliser, and it's possible it is causing your running problems (but not the gauge problems), although, with the genuine BMW alarm, fitted as instructed, there is no wiring associated with the immobiliser in the engine compartment. The siren and back up battery with its loom is there, but a problem with that loom shouldn't affect the engine.
You say that the immobiliser has been removed, and the engine still won't run?
If so, use a piece of wire to connect the coil + terminal directly to the battery + terminal (or the phantom battery terminal on the bulkhead, if your battery is in the boot), and try to start the car.
If still no luck, and since the engine loom itself is now possibly under suspicion, disconnect the loom from the oil level sensor under the alternator, turn back the rubber boot on the plug, and check to see if the brown/orange wire is burnt.

Post Sat Jan 25, 2020 1:34 pm

I'm sorry I've realised that I never updated this thread!
A very long story short ...
It was the Relay to the ECU! Diagnosed by a garage- Richard of Barkers Motor Works in Haslemere -
However 'en route' another garage had pointless removed the nice bmw new fuel pump and put in a cheap chinese one then 'lost' the original replacement one!!! I was most miffed and unhappy about that!

But the 'BMWorks' totally resolved that problem!