Heres the deal, 91 318i 157k, engine in good tune, good mechanical order, idles great and runs perfect, almost too perfect for its age/mileage.
Ever since I bought this car (back in jan) it has plagued me with a running issue whenever it is wet, raining or generally damp outside. It first arised when I washed out the engine bay and got water in the first 2 plug bores, blew out the water and it ran perfect, thought that was it. So here is what it does;
After rainstorm (sits overnight) go to start in the morning, cranks for quite awhile, check engine may flash, then starts, and then quits. Keep trying to crank and wait for it to start, then keep it running steady at 2k. It tends to run fine at fixed throttle, every now and then it will hick-up (check engine comes on when it does, but it tends to come and go very quickly). When varrying the throttle it will miss and sputter, cel coming on whenever the issue is there and suddenly goes out. The car runs completely perfect in dry weather, not a single issue. Check engine light never stays on and runs perfect after it clears up. Last time I pulled codes it threw for cam sensor, cam sensor less than a year old. Had the issue several times since then and did not check for codes.
I have replaced the crank position sensor. It has new plugs, wires and coils are old, but no arching and the boots look okay. If i pull the plugs after the car dies there is no evidence of fuel on them, so I have ruled out coils/wires, and moved to fuel. I checked out the main relay and popped the cap off to check for arching, thing looks brand new. The car will stay running if the TPS, AFM, coolant sensor, and cam sensor are unplugged (independently) so I dont really think any of these are to blame. This issue is cutting fuel (and possibly spark) and switching it right back on, so I am ruling out fuel pump relay cause this happens very quickly, too quickly for it to be shutting the pump on/off, it would make sense if the injectors where shutting on/off though. I have found that if the crank sensor is unplugged the car will die, crank sensor is new and made no change. I have also found what i believe is the injector harness connector?? Its a 3 pin connector running up to the injector box, this will cause the car to die if unplugged.
I am really leaning towards a problem with the harness or a connector. I coated all the connectors I could get to with dielectric grease and this seemed to fix the issue for a few weeks as it was driven through lots of rain without a single issue. Does anyone out there have any insights, or think this seems logical? I am trying to diagnose this thing and it is very hard to do, cause of the sporaticness of the problem. I try to mess with it whenever it acts up because it does it so rarely, but hasnt stopped since i bought the thing. I'm in a real bind cause the car is sold and I would really like to either fix it, or give the new owner a little bit of help in getting it squared away.
Ever since I bought this car (back in jan) it has plagued me with a running issue whenever it is wet, raining or generally damp outside. It first arised when I washed out the engine bay and got water in the first 2 plug bores, blew out the water and it ran perfect, thought that was it. So here is what it does;
After rainstorm (sits overnight) go to start in the morning, cranks for quite awhile, check engine may flash, then starts, and then quits. Keep trying to crank and wait for it to start, then keep it running steady at 2k. It tends to run fine at fixed throttle, every now and then it will hick-up (check engine comes on when it does, but it tends to come and go very quickly). When varrying the throttle it will miss and sputter, cel coming on whenever the issue is there and suddenly goes out. The car runs completely perfect in dry weather, not a single issue. Check engine light never stays on and runs perfect after it clears up. Last time I pulled codes it threw for cam sensor, cam sensor less than a year old. Had the issue several times since then and did not check for codes.
I have replaced the crank position sensor. It has new plugs, wires and coils are old, but no arching and the boots look okay. If i pull the plugs after the car dies there is no evidence of fuel on them, so I have ruled out coils/wires, and moved to fuel. I checked out the main relay and popped the cap off to check for arching, thing looks brand new. The car will stay running if the TPS, AFM, coolant sensor, and cam sensor are unplugged (independently) so I dont really think any of these are to blame. This issue is cutting fuel (and possibly spark) and switching it right back on, so I am ruling out fuel pump relay cause this happens very quickly, too quickly for it to be shutting the pump on/off, it would make sense if the injectors where shutting on/off though. I have found that if the crank sensor is unplugged the car will die, crank sensor is new and made no change. I have also found what i believe is the injector harness connector?? Its a 3 pin connector running up to the injector box, this will cause the car to die if unplugged.
I am really leaning towards a problem with the harness or a connector. I coated all the connectors I could get to with dielectric grease and this seemed to fix the issue for a few weeks as it was driven through lots of rain without a single issue. Does anyone out there have any insights, or think this seems logical? I am trying to diagnose this thing and it is very hard to do, cause of the sporaticness of the problem. I try to mess with it whenever it acts up because it does it so rarely, but hasnt stopped since i bought the thing. I'm in a real bind cause the car is sold and I would really like to either fix it, or give the new owner a little bit of help in getting it squared away.
Comment