i was having a misfiring problem, this was determined by a friend with a plug in reader, so we tried switching a coil to a different cyl. and no change. i changed the spark plugs now the engine runs great and very smooth. but now it will serge two or three times and shuts off, seems to only be happening at an idle and in gear. so we cleared the computer and tried it again this time it ran a farther distance, then the first time.and the engine light is back on again now my friend doesn't have any advice or cant pinpoint my problem. can you please help me
My car has 117000 miles.
My car has an automatic transmission.
This may be a sign of an imbalanced air/fuel mixture caused by a failing idle air control valve. This is a unit that monitors air intake as it is mixed with fuel prior to being injected into the engine. When this reads inaccurate data in terms of the air coming in, this will cause inaccurate adjustments to be made causing the wrong air/fuel mixture to be supplied to the motor. When this happens, this can cause the engine to surge or fail to idle as you have experienced. I would recommend having an expert from YourMechanic come to your home to diagnose the abnormal idle and follow through with proper repairs.