i have a 92 rs with TBI and every now and then it sounds like a backfire but im not sure i have changed the fuel pump, ignition coil and the cap and rotor and nothing seems to help it any other options would be appreciated.

 

does it run bad when it does it?

 

It might be the timing, air/fuel ratio or fuel pressure. Probably not the air/fuel ratio though.

 

have you done plug wires and sparkplugs yet? is your service engine light on? if so get the fault code tested and there ya go, but im sure you already wouldve done that.

 

Mine is doing the same thing, just not every now and then. it happens 50 percent of the time. It will run like crap one day, and then run great the next. What could it be?