[Ryan.haddock]

Hey guys I just bought my 06 GMC Canyon 153k miles. Overall I'm very happy with it but I have a question in the engine department and I by no means am a mechanic. I've noticed that while maintaining just about any speed, after while the RPMs will drop to around 1500. Almost as if the engine gets tired and slows down by itself. Any help would be greatly appreciated.

 

[xPosTech]

Are you really saying that while the truck maintains speed the engine slows down but the truck doesn't? Does the engine (and truck) really slow or does the tach incorrectly drop the indicated RPMs?

Ted

 

[silverado002]

That could be normal if you have a lock up torque converter automatic as it drops into direct mechanical drive. Should be happening at about 40-50 miles per hour or so and stay locked up until braking or required down shift. My 2002 locks up about 45 mph and hits about 1500 rpm and stays there until I brake etc.

 

[xPosTech]

I don't think that just about any speed would equate to 1500 rpm. Sounds to me like an intermittent stepper motor in the tach. Just about all automatics today will lock the converter.

Ted