First tell us what engine code/size you have in your vehicle. What faults you have (if you have scanned it) and when the mis-firing occurs. If it occurs first thing in the morning and/or when it's wet out, you'd have a leaking ignition coil and/or ignition wires.
Please consider a to help us answer more questions.
Wednesday, October 31st, 2012 AT 1:40 AM