Questions and Answers

Buick Regal Runs Rough Q. I have 1991 Buick Regal Fuel Injected. It has 140,000 miles on it, and has 3.8 liter engine. Every morning for about three weeks now; I will start it with no problem running smooth. Then about 2-3 mins later it starts running rough. It runs rough for about 5-20 minutes.

Then in the clear blue it runs smooth in a snap. It will sometimes start to run rough after I shut it off and start it again after a few mins even it is hot or cold. I have put a knew O2 sensor in and it didn't fix the problem either. The check engine light do not come on also.

A. You need to find out if it's dropping a cylinder while it's running rough. You can pull a plug wire at a time to see if any are not making a change in the roughness. Possibly corrosion on a plug wire at the coils or a bad injector.