Unusually High RPM on 2008 Tahoe LT

[Ed Alexander]

Hello All,
My 2008 Tahoe LT has an issue. When I go from either stop or slow driving position and when it is trying to switch gears the RPM's rev 3k-4k when it finally switches gears. Anyone have any idea how to resolve this issue? TIA

 

[swathdiver]

Where is everybody?

Sounds like a bad throttle body or big vacuum leak.

 

[Ed Alexander]

I recently changed the following:
Mass airflow sensor
Vapor Canister Purge Valve
Vapor Canister
Vapor Canister vent

 

[Geotrash]

Hello All,
My 2008 Tahoe LT has an issue. When I go from either stop or slow driving position and when it is trying to switch gears the RPM's rev 3k-4k when it finally switches gears. Anyone have any idea how to resolve this issue? TIA

Sounds like a transmission shift flare or delayed upshift to me. Root cause could be the throttle body, I agree, but could also be transmission valve body.

Can you capture a video, OP?

 

[Ed Alexander]

I changed the throttle assembly but it did not work out. I drove it for about 20 miles. Do I need to drive it longer to calibrate?

 

[Doubeleive]

I changed the throttle assembly but it did not work out. I drove it for about 20 miles. Do I need to drive it longer to calibrate?

Might take several days or just do a relearn with a scanner if you have one, not sure why random people have throttle body learning problems I have never experienced it and I cleaned, removed, changed, several never had a smidge of an issue

 

[Fless]

Might take several days or just do a relearn with a scanner if you have one, not sure why random people have throttle body learning problems I have never experienced it and I cleaned, removed, changed, several never had a smidge of an issue

You just never noticed it since you're always in high rpm.

 

[Doubeleive]

she idle's pretty good, even after putting a ls7 throttle body on, no relearn needed

 

[B-train]

What is the Trans fluid level when warmed up? Is it discolored or have a burnt smell? Should be bright red and have a smooth, sweetie smell if in good condition. What is the service history of this Trans? Is it the 4 speed or 6 speed? How many miles?

If it is throttle related and you replaced the throttle body, try using a scanner that has live data to see what the throttle position actually is when this happens. The old 700r4 transmission used a cable tied to the throttle linkage that you could adjust the firmness of shifts with. I know that's not how this one works, but if all else checks out, it's possible the throttle pedal has a dead zone in the resistance range that may be fooling things, which should show up on live data.

These are all speculative things that I feel can influence shifting characteristics. However, I'm leaning towards a transmission problem- fluid or mechanical

 

[Ed Alexander]

I checked levels and are all perfect warmed up. No discoloration or smell. This vehicle has 170k miles on it. Thanks for your help. If anyone has any other advise it would be much appreciated as well.