Okay, here’s the background. I’m about at my wit’s end, so I’m hoping maybe one of the car guys here will have some ideas. I have a 1996 Buick Century Custom with a 3100 V6 SFI Engine. The engine was replaced a bit over a week ago, because the old one had developed a constant misfire that wasn’t cured and the shop was suggesting $3k+ for a head job and teardown in the hopes that would solve the problem. The new engine was a reconditioned used motor, with 50k miles on it and a 1 year, unlimited mileage warranty.
I picked up the car on Friday and it was running fine, no problems, and I drove it home. On Saturday afternoon I got in the car and the check engine light was on, with the P0113 and P1406 (IAT Sensor Circuit High and EGR Valve Pintle Position Sensor, respectively) codes.
When I was driving to the parts store on Sunday to try and pick up a repair manual and new IAT sensor, the car totally died out – stopped accelerating at all. I could put my foot to the floor and get nothing, and then the engine died entirely and the battery and oil pressure lights came on. If I tried starting it right back up, it would start and immediately die again. If I left it to sit for 10-15 minutes, it would restart and run a while, but then die again.
Had my family mechanic looking at it yesterday, and we replaced an ignition coil (this car has the distributorless ignition) that didn’t seem to be firing from both sides and the fuel filter which hadn’t been done in years and was pretty full of crud. Neither fixed it.
Finally he found what we thought was it, the wire connector to the ignition coil assembly (the purple & yellow, 2-pin plug that goes in to the base where the coils are) seemed to be shorting, because if we pushed on or wiggled it at all, the car would immediately die.
So, today I replaced that connector (got a new connector, cut off the old one, and spliced the new on in) but am still having the same problem. The car will start and run perfectly fine for about 10 minutes, and then die. Makes no difference if the car is idling or if it’s driving under power, it still dies out.
The fuel pump seems to be working (can hear it kicking in when I turn the car on, and the car does run fine for the 10 minutes or so). The fuel filter has been replaced, the EGR valve has been replaced, the Intake Air Temperature Sensor has been replaced, and the Ignition Coil that tested bad has been replaced. The spark plugs and wires are all new.
The shop that replaced the engine is about 30 miles away, so getting it towed back up there is a costly proposition, and their answer is “If it ran fine for 3 days before it started dying, it probably wasn’t anything we screwed up, and all we did was swapped the motor, we didn’t change out anything else on your car, so if it’s ignition/electrical/fuel/whatever, it’s not our problem.” I’m at my wits end, so if anyone has some ideas I’d love to hear them.