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05 envoy xl 4.2 rpm up and down

1K views 4 replies 4 participants last post by  Cam TB 
#1 ·
I have a 2005 envoy xl 4.2 with 185000 on the odometer. While I was driving today I had the cruise set at about 62 and I noticed the rpm’s kept fluctuating up and down, it wasn’t hilly or anything either. Any idea what could be the issue?
 
#2 ·
Probable the TCC.

The torque convertor clutch never really gets to 100% fully engaged - nor does it get to 100% fully disengaged either.

It constantly slips and the PWM valve in the transmission valve body is the biggest problem with floating RPM at cruise.

There is a PWM/Delete kit available - and if you're not too squeamish about working in the valve body - it's an easy thing to do ---- IF the PWM bore has need egged-out the valve body itself and then you need to ream the valve body port and install the special part that takes up the new dimensions for the replacement PWM valve.

Actually, at this time - it's very likely that you need this service performed - especially if you've got some moderate mileage on this vehicle.

If you don't repair this - it WILL fail you --- be warned!

Installing a new PWM delete kits will make your TCC act like it's on steroids and you'll "think" you have a new gear in your 4-speed transmission. You won't; you'll just now be able to notice the apply/un-apply as it's gonna be a lot firmer --- that's good!

"Floaty" cruise RPM is almost always the TCC dying.
 
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