Misfiring and Fuelling Help Needed with my 1993 318is

[KevBoy]

Help please - i am stuck!!

My 318is was running lovely. All of a sudden i started it and it was running like a plug was fowled up and started backfiring.

After doing a few checks, a friend thought it might of been a valve problem as no's 1 and 4 were not responding to plug lead removal although there was spark.

I ended up removing the head but all is fine. I have replaced the head but the car is still running rough. I now also have a problem where the injectors on 2 and 3 are pumping fuel out of the inlet manifold and down the side of the block. I checked the seals and ended up swopping them with 1 and 4 but they are still leaking, therefore not a seal problem. Think that they might be overfuelling but not sure if they would pump fuel out if that happened.

So in a nutshell:
Head and valves fine
Timing is spot on
Spark is fine

overfuelling on 2 and 3,  but suspect that no fuel to 1 and 4, hence misfiring.

Can anybody shed some light on this one

Thanks

[kenika65]

Wow I am sorry you took your head off, hope you laped your valves atleast...

Have you done a compresion check?

I am guessing not because if you did then you would have found no reason to pull the head off...

Have you checked spark on all four cylinders to make sure you are getting strong and constant spark.

If you are having a fuel problem then you may have a leaking injector or a clogged injector, you would have to take them off and watch them spray to make sure they are spraying properly and not leaking to eliminate the injectors.

Next would be your crank sensor which may be giving the wrong signal causing your fuel problem.

Also a small vacummed leak will cause all kinds of problems on these m42 because they rely on vacummed for everything to work correctly.

So I would suggest you smoke your vacumed system.

If you need more info just ask.

Also the m42 coils are know for burning the threads off of the spark plug cap which will and does cause a misfire.

[KevBoy]

Thanks for the info.

I have done a compression test and thats ok. All plugs are sparking. I  have had all injectors out and swapped them round but the the same two ports are leaking fuel on to the inlet manfold, so therefore its not the actual injectors.

Does anyone know if this is an ecu fault. Not fully up on these and wondered if a fault would cause only two ports to receive fuel as i noticed that No's 1 and 4 injectors were dry.

[KevBoy]

Right i have now got a bit further.

The fuel leak has stopped - turned out to be a perished fuel pipe under the inlet manifold that was spraying fuel onto the injectors - hence why I thought the fuel was coming out of them.

If i leave the ecu unplugged for a while and then plug it in, the car starts and runs fine for a while until it warms up. It then starts to run lumpy and eventually misfires and when revved up pops through the airbox and then cuts out.

I have tried leaving the ecu plugged in overnight and the car misfires straight away - which i assume is because the faults are stored in the ecu.

I have today got hold of an identical ecu, plugged it in but no difference.

Any ideas please.

[EN318isPDX]

Fuel pressure is my guess Kevboy. it could be just the filter.. start with the filter its only 10 dollars compared to 250 for the fuel pump

[kowalski]

could be the regulator too. are you getting fuel on # 1 and 4? is the fuel rail bolted down? Are they all the same injectors?

sounds like you might have messed up the seals on the injector tips or something because they obviously shouldn't leak... go buy some new ones and try swapping the injectors around to see if the problem follows the injectors.

[KevBoy]

Finally found the problem and feel pretty peeved........

Plug leads 1 and 4 had tiny holes in the side of the rubber sleeves and were therefore sparking in the head and causing the misfire.

Took the plugs out to check them and put a plug on each lead to check that they were still sparking when i saw the spark come out the side.

Put some insulation tape on them and the car started and ran perfectly.

Gutted or what.

Thanks for our help.