2002 GMC Sierra 1500 - Slightly fluctuating RPMs

[david5292]

I have a 2002 GMC sierra 1500, V6 4.3L. I am having an issue with the RPMs slightly fluctuating when accelerating. It does not seem to do it all the time. Or eventually it will go away for a while and come back when driving for a while.

 

The RPMs generally only jump up an down less than 100 RPM or so (it moves very little). You can actually feel the trucks RPM changing so not a gauge issue.

I don't think it fluctuates when idle (at least I don't see it), mostly just during acceleration, when speeding up its hard to notice, its usually when you are driving steady. I tend to mostly see it in 3rd gear, but I believe it does it in every gear, just not as noticeable. Transmission also seems to shift fine.

 

There are is no check engine light, and no codes.

 

Recently had a tuneup done, new plugs and wires, so no misfiring. Replaced both catalytic converters.

I will be installing a new fuel filter soon, so may see if that does anything.

 

Things I suspect may be issue:

• Fuel filter - will replace soon
• Throttle body/Sensor - will try to clean it and test the sensor for resistance
• MAF Sensor - will try to clean it
• Transmission/Converter
• Exhaust leak - haven't checked yet

 

Any ideas what could be wrong?

[chem_man]

I would check the fuel pressure to make sure that it is within specification, and check your fuel pressure regulator for proper operation.

 

When you say that you are going to test the "throttle body/sensor" for resistance, are you referring to the throttle position sensor?

[rjgti]

does that v6 have a dizzy, if so replace cap and rotor with delco's

[sefiroxx]

Check the tranny fluid as well. Things maybe starting to go.