I am trying to help a buddy with his V6 Chrysler Cirrus that has a rough engine problem. He'* had it into the mechanics (several different dealerships) over the last year, and none of them seem to be able to fix the problem. he has spent over $2,000 in trying to repair the car, but nothing has worked so far. I don't know exactly what he has done, but I know that the ignition module, spark plugs, wires, fuel filter, fuel pump, and computer have been replaced and the problem is still there. Here'* some facts about the problem:
1. It only happens when the engine is warm. (driven atleast 8 miles)
2. The harder the car is driven, the more quickllyy it will start to run rough.
3. The engine runs rough when the check engine light is OFF.
4. The engine runs smooth when the check engine light is ON.
5. When the check engine light is on, and the engine is hot, the light is flashing.
6. When I use my scantool to scan the car for codes, nothing shows up.
My thoughts on the problem is a bad sensor of some kind. If the check engine light is on, and the car runs BETTER, I think that maybe the car is running under a default timing of some kind so the car runs better? When the light turns off, that means that the PCM is using the car'* sensors to maintain the vehicle and if an important sensor is giving false readings, couldn't that mess up timing, or fuel/spark? I'm really not sure..