I have a 97 4.0 Jeep Cherokee. Since I bought it I have replaced the cap, rotor, wires and plugs. It runs great but I keep getting check engine light for randon cylinder misfires. I have Seafoamed it and swapped the injectors for 307s. Same issue. Any other ideas?

Thanks,

Flash

 

Could it be the coil? O2 sensor? What else would cause this condition?

Flash

 

o2 sensors. Get a code reader on there before doing anything else. Both o2's will run ya over 200 bucks for the good ones so be methodical.

 

what kinda plugs are you running?

 

New Denso U Groove. .035 gap.

Flash

 

Random misfire code is often caused by one "common" root cause.

The first thing I would do (and what a shop would do) is to verify proper fuel pressure. This must be done with a gauge; anything less is guesswork.

For a 97, you should have 49 psi, plus or minus 5 psi.

A major vacuum leak is also a primary suspect with a random misfire.

Start there.

 

Can be a knick in an electrical wire in the wire box, this happened to me it was sending wrong pulses to the fuel injector.

Look at my post concerning my issue I just replayed on it today