Missing problem

[turboman38]

I've had a missing problem for around a year. I've replaced the coil pack,module,MAF,O2,Crank Sensor,Wires and plugs. I've also tried to eliminate any vacuum leaks. It happens under light load at a steady speed, especially in the lower RPM range. Car runs great when you mash the gas. Anybody have any idea what this could be?

Can a coil pack be bad in the lower RPM range and be ok in the upper range?

Could the wiring harness be bad somewhere?

Could an old positive side battery be the problem?

Any help and suggestions are appreciated.

 

[6=8]

How is your timing chain doing?

I had a stock one that was so loose, it was affecting the the camshaft sensor (Which after starting the car is used by the ECM to control the fuel injector timing.)

Just for grins, start the car and unplug the cam sensor. (The injectors sound kind of funny in "Batch Fire" mode!) Take it for a spin... see if the missing goes away.

If it does, best case is the sensor needs adjusting. Worst case, it's time for a new timing chain AND you have to re-adjust the sensor!

If nothing changes, look toward the IAC or possibly a sticky EGR or its controls.

I actually got a lot of miles out of my chain: 147,000! How many miles do you have?

Hope these ideas help!

 

[turboman38]

Thanks for the input! Batch fire mode is a good suggestion. Timing change is new. Entire motor has about 8000 miles on it and had all new internals put in it when it was rebuilt.

 

[striker_29]

I know you said you replaced your wires, but it sounds like a bad wire to me. I would also check all the grounds very carefully. Good luck.