Rpm bounces while moving

[Husky05]

Cm871 deleted, when I'm moving the rpm bounces 2 or 3 time then steady for 2 seconds, bounce again. When I put it in neutral, hold it at a rpm like 1400 does this. But when I'm parked, and hold it at 1400 it doesn't do this.

All fuel solenoids, shut off solenoid, pump, lift pump are new, I even took the IFSM off tore it apart cleaned it, checked and replaced gaskets/oring. Still doing this. Speed sensor is new. Replacing filters don't make difference.

4 injectors are new, 2 injectors are 130k miles.

Injector leak test passed, ran all test on insite all passed.

I am lost here.

[mj9770]

Bad throttle position sensor or wiring? When your plugged into it does it show any change on the computer about throttle input changing?

[Husky05]

I did not think of that will check it in a hour

[Signature620]

When you say bounce, is it losing rpm or increasing rpm?

[Chamberpains]

Watch the TPS voltage fluctuations. It will show a voltage spike or drop better than watching the TPS count.

A side note. If you're getting voltage fluctuations on an evenly held throttle pedal, its not always the sensor. So don't just throw one at it right away. Could end up being a waste of $$. A lot of times its chaffed wires somewhere under the hood. Often times under the loom clamps around the back of the engine. They are a 5 volt circuit and are much more of a delicate circuit than a standard 12v. There are 3 wire twisted to each other. Signal+ signal- and 5 volt feed.

[Husky05]

Ran graphical monitoring, the accelerator pedal position voltage and percent accelerator stays steady when the rpm bounces, the rpm actually drops then resumes.

[Chamberpains]

What is your fuel psi doing when this happens?

Is this a real fast drop? Almost a stutter? Or slower?

Did you put your laptop up on the dash and watch the TPS voltage? Reason I ask is I don't know what the recording rate is when using graphical recording. On my cm870 its retardedly slow and my TPS voltage drops were very fast. The graphical monitoring wouldn't catch it happening. I had to monitor just the live feed using Insite of the sensor alone. It would drop out so fast that it only dropped .3-.4volts. Not enough to kick a CEL but enough to cause the engine to stutter only when moving the truck. Ended up being crappy sensor wires around the back of the engine.

[Husky05]

The rpm drops 2 or 3 times within 2 seconds.

I can adjust the log rate to 20 milliseconds, I usually run 1 seconds. I can try 20 milliseconds.

However I noticed idle rocks my truck 2 or 3 times then steady and do it again. I've attached shot of the data. That's idle no touching anything. That's how much the voltage bounces from minimum to maximum numbers. I guess it's supposed to be steady at idle?

[Chamberpains]

That screenshot isn't showing to much. It caught your RPM's dropping to 635 which may be a slight drop but that is within normal fluctuations. But it also could be explained by the .07 volt drop on the Accelerator Signal voltage. There is nothing definitive that I see.

Try the 20 milsec graphical recording on the Accelerator signal voltage and your RPM at the same time. See if it'll catch your event and maybe the 2 will drop at the same time.