Checking to see if this sounds familiar to anyone. I have a very noticable high/low revving sound from the engine when the rpm's reach around 1800 to 2000. This often occurs when under load or there's pressure on the throttle. When the truck shifts into the next gear and the rpm's drop the revving disappears, or when you left off the pedal it quiets. The rpm's on the tach are not affected when this occurs. No loss of power and other wise the truck runs good. I should also add this does not occur all the time - mostly when it's cold. It this something electrical and connected to my fuel sending system. New lift pump put on thee months ago at 113K miles. Checked and found no codes.

01 2500 QC 4X4 Auto, Edge EZ, 4" exhust, KN filter, Solidsteel TB System.

 

this seems very similar to what i am going through right now, almost like a surging feeling and to me i think its the torque converter going in and out of lock up. i posted the thread right below yours about the same thing

 

My buddy's '02 was doing something real similar to what you've described and his problem ended up being low fuel pressure from his junk stock lift pump. Do you have a fp gauge?

 

Sounds like the fan may be kicking in. that gives the impression that the rpms are higher. If so, you need to clean the radiator and relocate the crancase catch bottle and clean the radiator to avoid major overheating problems in the summer.

 

thanks, thought about the fan blades about a week and found them to be very dirty....even bought cleaning stuff but haven't done it yet.

Back in August 08 I had trans problems and had the solenoid and transducer replaced, plus the bands were tightened as well. Wondering if the trans work is an issue, and should I have the TPPS reset to work with the trans. My shifting patterns seem off and extended, especially from 3rd to 4th gear. It during this shifting transition period when the revving is most noticible???