nick3791
08-24-2024, 11:25 AM
I'm hoping I can get some verification on whether I have an ECU issue before I pay to send it off for repair. 1997 328i RHD touring automatic I recently purchased and imported. Has been idling rough since I got it, but smooths out after throttle applied, especially after 2500 rpm. Seller swears it was fine when dropped of at the port. I am inclined to believe him as he has helped pay for some other issues, plus I know he doubled his money on the sale. At this point it doesn't matter. When I picked up the car, the battery died on the way home as the alternator was dead (perhaps a clue/cause to ECU having an issue now)
Swapped motor mounts (one was crushed) no change, replaced fuel filter and air filter, no change.
There is no CEL on European models and it is pre OBD2 there. With Carly OBD2 hooked up to the 20 pin port via adapter, I am getting a misfire on Cylinder 5. No other codes pulled up
Prior to testing more (including pulling the code), I also replaced spark plugs AND coils (figured tune it up either way, so spent the money on new). No change
I replaced all 6 injectors
I cleaned and then replaced the ICV, no change
Replaced manifold gaskets and visually checked all hoses (replaced one from the Fuel purge/valve that was suspect looking), no change.
Then I got wise and started testing things instead of just throwing money and time at it.
1. Compression was good.
2. Unplugging coil 5 made no difference in how the engine idled, but unplug any other coil and it worsened dramatically.
3. Using an inline spark checker kit, I get no spark on cylinder 5, regardless if I plug it all the way to the spark plug, or just the coil to ground. (I also moved the spark plug just to make sure I didn't get a dud, and the coil, no change)
4. I then checked continuity in the coil harness to the end of its plug, all good.
5. Checked continuity from the ECU plug all the way to the coil, all good there as far as I can tell (with the help of my 72 year old father, an electrical engineer and DIY car guy most his life).
6. I also checked voltage to the coils with ignition on and they all had the same.
Conclusion ECU at this point? Am I missing anything else. I would ideally check the signal to the fuel injector, but being they are all on one solid harness, that seems difficult and I don't want to pull off all 6 and lose one of those stupid connector clips again, it took me hours with the manifold off to find one. I'm not sure if another issue could cause the ECU to not signal the spark, like an injector not getting signal.
Any help is appreciated. I just don't want to waste another 200 bucks (and time) to send off the ECU for it to be fine
Thanks,
Nick
Swapped motor mounts (one was crushed) no change, replaced fuel filter and air filter, no change.
There is no CEL on European models and it is pre OBD2 there. With Carly OBD2 hooked up to the 20 pin port via adapter, I am getting a misfire on Cylinder 5. No other codes pulled up
Prior to testing more (including pulling the code), I also replaced spark plugs AND coils (figured tune it up either way, so spent the money on new). No change
I replaced all 6 injectors
I cleaned and then replaced the ICV, no change
Replaced manifold gaskets and visually checked all hoses (replaced one from the Fuel purge/valve that was suspect looking), no change.
Then I got wise and started testing things instead of just throwing money and time at it.
1. Compression was good.
2. Unplugging coil 5 made no difference in how the engine idled, but unplug any other coil and it worsened dramatically.
3. Using an inline spark checker kit, I get no spark on cylinder 5, regardless if I plug it all the way to the spark plug, or just the coil to ground. (I also moved the spark plug just to make sure I didn't get a dud, and the coil, no change)
4. I then checked continuity in the coil harness to the end of its plug, all good.
5. Checked continuity from the ECU plug all the way to the coil, all good there as far as I can tell (with the help of my 72 year old father, an electrical engineer and DIY car guy most his life).
6. I also checked voltage to the coils with ignition on and they all had the same.
Conclusion ECU at this point? Am I missing anything else. I would ideally check the signal to the fuel injector, but being they are all on one solid harness, that seems difficult and I don't want to pull off all 6 and lose one of those stupid connector clips again, it took me hours with the manifold off to find one. I'm not sure if another issue could cause the ECU to not signal the spark, like an injector not getting signal.
Any help is appreciated. I just don't want to waste another 200 bucks (and time) to send off the ECU for it to be fine
Thanks,
Nick