I performed a tune up on my Formula this past weekend and after some driving it seems to be running a little rough. The plugs were changed along with the oil,all filters changed and plug wires checked for excessive resistance or burnt spots. The car also has a new HEI module in the distributor after it failed a week ago. Cap and rotor checked and terminals cleaned. The rough running seems to be a cross between a slightly lumpy cam and a slight miss. It's only happening when the car is idling in gear and the exhaust smells slightly rich. There are no codes present. I'm looking seriously at the O2 sensor and the IAC motor possibly needing cleaning. Anyone have any thoughts?

 

Maybe to obvious but did you set the timing? I tuned my 91 formula and change coils, cap, rotor, etc and it was running a little rough till I set the timing. On mine I found I got the smoothest running while still advancing it to about 8 deg btdc.

Larry

 

Did you unhook the EST wire when you set the timing?

 

Timing was checked but not changed. Mine is a TBI car and is set at 1 degree advanced.