Misfire on Cylinder 5

[Slovik]

The car is a 91 318is S52 OBD2, I got on the car hard yesterday in 1st gear up through 2nd and got a misfire and check engine light. Limped the car home and hooked up the reader and got PO305 (misfire Cylinder 5) and no other codes. Pulled the coil off of 5 and switched it for known good one I had laying around. Turned the back on and it runs perfect, figure I'm a genius. Today I run it hard up through the gears and get the same misfire, cylinder 5. This time I swap plugs and coils from 5 to 4. Start it up runs fine. Run it hard through the gears again and get cylinder 5 misfire. If I just shut the car off and restart it the misfire goes away every time. Seems obvious that it is a fault with wiring on cylinder 5 but where should I start, do the coil connectors go bad? Why would the car reset itself after a shut off each time. The car has run perfect for almost 5 months since the swap and nothing recently has changed. Any thoughts would be greatly appreciated.

[328ijunkie]

Check compression :/

[Slovik]

Thanks Junkie I'll do that tomorrow but I really feel like it is electrical as the car misfires until you turn it off and then it is fine on restart and runs perfect. If I don't blast out of the hole, I can rev it to 6k or so with out it happening.

[DesertBMW]

Where did you get your OBD2 ecu tuned?

http://www.r3vlimited.com/board/showthread.php?t=261153

[328ijunkie]

^didnt see that coming. Oh wait. I did.


Your ecu is smart. It sees something wrong and it shuts down that Cyl till either it feels it's safe to restart or until you restart the car..

[Slovik]

The ECU wasn't tuned so to speak, I had TRM leave all parameters stock just delete the rear O2 sensors, EWS and Raise the idle a bit as I run a light flywheel. It has been running fine for 5 months so the "tune" is pretty unlikely issue. I did go back and read that post though, I wonder if I could have a bad injector, how would one test for that?

[328ijunkie]

Eat a shoe DesertBMW. :P



try swapping an injector. Sometimes they can intermittently stick.

[Slovik]

Makes Sense!! Thanks Junkie

[DesertBMW]

The ECU wasn't tuned so to speak, I had TRM leave all parameters stock just delete the rear O2 sensors, EWS and Raise the idle a bit as I run a light flywheel. It has been running fine for 5 months so the "tune" is pretty unlikely issue. I did go back and read that post though, I wonder if I could have a bad injector, how would one test for that?

Tune is the most likely issue if you changed the coil, spark plug, I had a coil melt on cylinder number 5 with TRM tune, they do some tuning to coil dwell time and that resulting coil driver gets too hot stops working or simply shorts itself

[328ijunkie]

So basically everyone tuning OBD2 ruins everything except you? TRM is Technica's direct competitor and ive honestly got nothing bad to say about them/their tunes.

Again, swap the injector and check compression. I hardly ever see wiring harness issues, and have never really seen a tune cause 1 specific cylinder to continually shutdown.

[Slovik]

Found the problem this morning, Put the reader back on it and got a second code P0205 (open circuit #5 injector) it is the injector connector. One of the contacts is pushed back into connector. I no doubt did this when I was experimenting with some yellow tops a few weeks ago. Problem is how do I correct this, is there a way to replace that connector?

[Slovik]

Maybe this? https://www.autohausaz.com/search/pr...98&cid=22@Fuel %26 Air System&gid=11222@Fuel Injector Repair Kit

Part number 1287013003 if that link doesn't work

[Boosted E30]

Just open up the plastic cover that contains the injector harness and push the wire back into the connector.

[328ijunkie]

wow. Beauties of OBD2 :D

+1 Open injector harness box and you should be able to snap pin back into its slot. If not you can buy a replacement pin, crimp and reinstall.

[Slovik]

Fixed, Took 2 minutes. Thanks Junkie, Boosted and Desert, This is exactly why I wanted to go OBD2 in the first place!