My wife's '90 notchback has been running poorly lately. I pulled the plugs yesterday and the front two show signs of the cylinders running rich. The back two looked fine. I tried running codes and got none (no check engine light either). When I started the car, there was a great deal of carbon (black smoke) out of the tailpipe. It left quite a black spot on the drive. Where should I go from here? BTW, I put a new head and injectors on about 9 months ago and it was running like a champ. Shopteach
Try checking the distibutor cap there might be a crack in it. Even thow you have new injectors it's possible that they are hanging up "not closing all the way". Allthow It is strange that cylinders 1 and 2 are both rich, I kinda of dought that it is your injectors.Are the plugs wet also?if so check plug wires, hope this helps some
I've thought of the wires and cap. I replaced them at the same time as the head. That doesn't mean they're still good though. The plugs are a dry powdery black, just like the patch on the drive. Its possible the injectors are hanging open but I thought maybe I should look elsewhere first.
I don't know if this will work for a '90. On my '93 the Engine Coolant Temp sensor connections corroded to the point that it lost connection, essentially telling the computer the engine was very cold and causing cold-start enrichment. Had the same symptoms you're describing and won't set a code because, well, to the computer it's an acceptable condition. The fix isn't the sensor, it's the connection. Give it a look, it's a quick and easy check. Good luck
This happened on my 85' SVO and this sensor is not easy to get to. I would try the easy stuff first like trying to wiggle the plug up and down a few times to help get a good conntact. I would also check the O2 sensor connection. I find it weird that you are running rich and no codes like a 42# or 21# to point you towards the cause of it
