I have been troubleshooting a miss for several months now. I have changed the coils, plugs, wires, checked the fuel pressure and compression. Everything checks ok but it still misfires. Only time it doesn't do it ( that I can tell ) is at full throttle. It only does it at idle and cruising speeds. I have also changed the tune numerous times. It is driving me crazy. Anyone run across this problem?

 

Have you run a scan to see wht Cyl it is on....could be a valve or a bad spring.

 

Its not showing a misfire. Thats whats crazy. It just shows the timing jumping all over the place. I'll have to check the springs.

 

Hmmmm.......got a screen shot?

 

How long has it been doing it? Before the tune or after? Dyno tune?

 

It was doing it before the tune. After I put the turbo on. I have checked everything I can think of. I have tunnel vision now. Needed to bounce it off someone. I ran it on the dyno and the graft was preety choppy. AFR went below 10. So I know its not lean.

 

Hmmmm lets back up a second....it started after the Turbo?

 

What are your plugs gapped at?

 

Plugs are gapped at 30. They were 35. I changed that to see if it would make a difference.

The problem I got when I first put on the turbo was it would shudder a little when excellerating and when you were off the gas it would buck. The problem as progressively gotten worse. I have always had a vibration that would come and go when cruising the interstate. I believe when I put the turbo on it just made it worse and more noticeable. It has a new trans, eaton posi and converter. So I know its none of those.

 

I had the same problem after my whipple install. Allen Nelson swapped my '00 PCM for an '02 PCM. All the prolems went away. I know some others have made the same swap and rave about the results.