Transmission or Ignition?

[jetmech]

Put the pedal to the floor on the freeway today and discovered a problem. The truck started jerking in an unconsistent manner. It only seemed to do it at higher RPM though. I can't tell if it's the trans starting to slip or an ignition component - coil, wire or plug. I put a FLT lvl 4 in about a year ago, the spark plugs are about a month old, the wires are about 2 years old and the coils are about a year old. One more thing, the wires have been taken off and put back on many times - don't ask. Please help

[txarkitekt]

From the sound of it, its not the tranny. Its either fuel or spark. One way to check for the fuel is to put a mechanical gauge on the Schrader Valve and see what pressure you are running. Idle should be ~38 psi...WOT should be ~58 psi.

If nothing there, I would go to the wires/plugs first. Replacing wires/plugs is simple and easy. From there, if no luck, I would have your tuner do a scan and maybe he can help decipher your problem.

[jetmech]

funny you mention fuel pressure cuz I'm putting in an electronic fuel pressure gauge that is visible from the driver seat.

[r.barn]

+2 fuel or ignition.

coils, plugs, wires, fuel filter, codes. good places to start checking the easy stuff.

I would start by pulling codes and checking spark plugs for color and/or fouling.

Saw you have MSD coil packs too.
Will never buy another MSD ignition product EVER again with all the headaches I've had with their stuff.
bad coil, bad brand spank'n new distributor, bad ignition boxes.

[txarkitekt]

Saw you have MSD coil packs too...

Don't agree with ya about MSD stuff being bad...but I will agree that the money spent on MSD Blaster Coils for ANY LS-based motor is a COMPLETE waste of $$$. Oh well, we all live and learn.

[RedHeartbeat]

check your grounds. I found I had a miss in mine and come to find out I had a fuel leak hitting the #1 injector.

Check your grounds.

[GasGuzzler]

Idle misfires are usually fuel related. This counts lean idle vacuum leaks.

Load misfires are usually ignition related.

To be clear misfires in this discussion do not consider "falling on it's face under load because of low fuel pressure or volume", only real misfires.

[jetmech]

the problem is only present in the high RPM range

[GasGuzzler]

Sounds like a lack of fuel volume. Do you have a wide band?