Engine/Transmission (1998.5 - 2002) RPM Oscillating...

[drag racer]

Went on a test drive this evening just before leaving for a fairly long road trip (vacation) on Monday, and had the following happen for the first time: while cruising at 40-45 mph @ approx. 1600 rpm in overdrive, with a steady pedal, the engine began a slow oscillation between 1500 and 1800, lasted for approx. 5 seconds, and then would stabilize. It did this a few times during a 20 minute drive; it was not violent, but definitely noticeable. Went up to freeway speeds, and ran fine. Any body have any thoughts what might be going on?



Thanks,



Eric

 

[Big_Daddy_T]

All I can think of is tc locking and unlocking. at 45 is where it locks on stock trucks i believe. Maybe it got confused. My truck has done this also on an intermittent basis for years. Usually the rpm change is very quick. Was there any power loss? Or did it feel like it was changing gears? How many miles on your truck? Any TC shudder to date?

 

[drag racer]

Big,



Haven't had any shudder problems to date. Engine/drivetrain 100% stock; 6600 miles. No loss of power when it was doing this; I would say the feeling was like it could have been hunting between 3rd and OD; I guess it just caught me by surprise, because I have driven at that speed before and never experienced that.

 

[Wolfgang]

Mine used to hunt between 3rd and 4th until I got the Smart Controller which changed the shift point to 55. What I found was that going up a hill it was much more noticeable.