engine runs very rough "NOW SOLVED"

[sharpster73]

Hi gents and ladies.

It seems that i need your help as i just can't figure it out.

I had a water leak on one of the engine block metal caps and to fix that i had to remove the intake manifold and air box.
Now everything is back together, but the car starts and imediately stops. If i try to help the engine by giving it a bit of throtle it initially hesitates to run, but then backfires and revs for a few seconds and then wants to die again. This will repeat for as long as i give it a bit (not much) throtle.

I have checked the injector loom and it is pluged correctly, all connector are back in and no joy.

The engine was sweet before this work, so it doesn't make any sense to me.

Can you guys please help?

****UPDATE****

Just an update on this problem as its now solved and i though that i should share the problem with you guys, who knows, it might help someone else.

It turns out that the 2 O rings from the tube that joins the intake manifold and the engine block were too old and were not sealing properly, allowing air to be sucked in. New O rings and the engine is now back as it was before.

Thanks for your help guys.

Many thanks

[kam-325i]

which engine ?

[sharpster73]

Sorry, my bad. The engine is M20B25 1989 facelift. Cheers

[Grrrmachine]

Either a massive air leak, the TPS is disconnected or you're overfueling.

http://www.e30zone.net/e30zonewiki/inde ... #Air_Leaks

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

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

[Brianmoooore]

I'd be having a good look at the C192 at it's wiring.

[Ajsingh]

Tps and air flow meter connected?

[bodger]

I'd be having a good look at the C192 at it's wiring.

Especially below the plug, pull the cover off and check for corroded/broken wires

[Grrrmachine]

I'd be having a good look at the C192 at it's wiring.

That is covered in the "Rich Running" section of the Wiki that I linked to, although why do you refer to it as the C192? It shows up as C191 in all my wiring diagrams...

[sharpster73]

Thanks for the replies guys.

To answer your questions:

TPS checked and AFM connected, C191 removed and cleaned and no corrosion there.

The only different things from before are cleaned throtle body, injectors and manifold, adjusted the TPS to "click" as you open the throtle as it wasn't before. Not long ago i replaced the roker cover gasket and the "D" rubbers and that curred the air leak i had before. The engine was so sweet i feel anoyed now. What's worse is that its my daily runner.

I will unplug the ECU tomorrow and check some connections (blue sensor, etc). Do you guys know which pins i should short at the relay to check the fuel pump? Also, is there a schematic for the injector loom that i can use to check the wires from the C191 to the injectors and blue sensor?

Many thanks for your time.

[Grrrmachine]

Its all in the Wiki:

http://www.e30zone.net/e30zonewiki/index.php/C191

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

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

[sharpster73]

Thank you for that, i will check them tomorrow and see what happens.

[sharpster73]

Hi again. I had another go at my car today and no luck. The things i checked so far:

TPS at ECU plug idle and WO - ok
Blue sensor at ECU - ok cold and warm
Injector connectors at ECU and at C191 plug as well - all ok
Crank position sensor at ECU - ok
I have tried a second AFM from a working E30 325i - no difference
AFM connections at ECU - ok
Checked rubber boot at AFM and throtle body - no issues there
Bridged the fuel pump relay and the pump is buzzing.
Swapped the ECU from a working E30 325i (although automatic)
Checked ICV connections and voltage - Ohm resistance ok, but voltage only 4.5V between middle and one side (although i have 12V between middle and ground and 10V between the other side and middle). I read in the Wiki that i should have 10V on both sides???
Removed AFM with engine running at very rough idle (450 RPM) - no difference
Removed ICV with the engine running and no difference. The ICV is cleand and buzzing.
Removed the oil filler cap with the engine running and no difference, although before this happend, if i did the same the engine would iddle lower and not as smooth. This makes me think of an air leak somewhere, but i had no carb cleaner spray to test it and check.

From these checks can you guys think of anything that i missed and i should check?

I have to take the bus now and its not fun.

Many thanks again.

[Sanchez]

Have you put back the inlet manifold properly?

If the engine was running fine before and not now why not put the old items back on.

You mention new TB, injectors and Mani. Put the old TB back on see it that helps.

Have the 'new' injectors been cleaned properly?

Are they the correct injectors?

[Grrrmachine]

Does sound like an air leak to me.

[sharpster73]

Have you put back the inlet manifold properly?

If the engine was running fine before and not now why not put the old items back on.

You mention new TB, injectors and Mani. Put the old TB back on see it that helps.

Have the 'new' injectors been cleaned properly?

Are they the correct injectors?

Those items you mention are not new, i just clened them properly before mounting them back on the engine.
I will do an air leak test and report back.

Thanks

[Sanchez]

Best thing is take your time and go over the removed parts and check for correct fitment.

You'll get there.

[sharpster73]

See updated original post.

Thanks

[Sanchez]

[capri_rob]

Thanks for posting this - I bet this is why mine idles rough as hell
It starts fine and the instant you touch the throttle its perfect - but the idle is lumpy as hell.

Had a right game getting that tube between the block & inlet back in place - and I'm sure the O-rings werent the best - looks like the manifold will have to come off again

[ferret-face]

I'd be having a good look at the C192 at it's wiring.

Location?

[Grrrmachine]

That is covered in the "Rich Running" section of the Wiki that I linked to, although why do you refer to it as the C192? It shows up as C191 in all my wiring diagrams...

Type that into the Wiki

[sharpster73]

Had a right game getting that tube between the block & inlet back in place - and I'm sure the O-rings werent the best - looks like the manifold will have to come off again

The easy way for me was to compress the spring on the tube, then strap a thin cable tie on the tube to keep the spring in place. This will allow you to put the tube into the block (o ring first, then the flat washer and a bit of oil to ease the tube in), then slide the manifold onto the studs and then after i hand tightened two nuts on the manifold i was able to release the cable tie and align the tube in the manifold. Having the o rings oiled helps alot, but you have to make sure that the top of the tube sort of "clicks" in the manifold. This will mean that the top o ring has seated correctly.

I hope this makes some sens and it helps.

[capri_rob]

I used the cable-tie method to compress the spring but I need to check with the engine running whether this pipe is the air-leak culprit - i strongly suspect it is as I've checked everything else and had forgot that this pipe can also cause air leaks It may just be that its not properly seated - fingers crossed.

I could really do without having to take the sodding manifold off again though