Hello,
Here's my story. One night I was driving my 1990 volvo 240DL AUtomatic Sedan home in a snow storm and the check engine light illuminated. I immediately thought oh somethings wet no big deal. Car ran fine had a rough idle though. So it didn't go away after a few days so I wrote to birckboard. Got the suggestion to clean the MAF and throttle body. As instructed I cleaned them and it helped. After cleaning and reinstalling I reset the computer by pulling the 25 amp fuse for a minute and when I started it ran great! But about 5 minuets after the car went back to its rough idle. When idling it shakes but when you gas it the engine does not hesitate and runs very smooth no backfiring. But it does blow out white smoke and there is a scent similar to a Desiel engine. Could this mean the car is running rich? I have noticed a drop in mpg not to crazy maybe 5 miles per gallon. Also before I cleaned the MAF i could unplug the wiring harness from it without bothering the motor. However since cleaning it if I unplug it the car stumbles and upon reinstalling the wiring the rpm's increase and stay high. When I unplug the O2 sensor wire in the engine bay with the car running it does change the way the cars running. Would this mean the car isn't getting a signal from the sensor? Back to the Smoke my fluid levels have not changed at all the oil and coolant are exactly where they should be and the car is not over heating. I do not have a check engine light on now but when i did it was a reading of 1-1-3. If you hit the gas there is a sucking like noise coming from behind the center air vent and they heat does not seem to shut off(don't know if that has anything todo with it, thought i would just through that it.) Any comments suggestions or tips you have please let me know. I willing to try everything it's fun and i want to bring my best friend back.