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High RPMs during morning commute


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darthsmozers
New User

Feb 21, 2024, 11:11 AM

Post #1 of 2 (465 views)
High RPMs during morning commute Sign In

First timer here.

I brought my 2019 Chevy Cruze (50k miles) to the dealer for a state inspection and left with an oil change, new tires, and suggested BG GDI Induction, Transmission Flush, and Brake Fluid exchange.

Immediately upon next using the vehicle, I noticed something new: During my morning commute, I noticed when reaching highway speeds (70 mph) the RPMs would get stuck at 3 and not shift back down to 2 or 2.5 as usual. The car would sound like it was working extra hard and this would continue until exiting the highway back to slow speeds or coming upon traffic - a daily occurance - forcing me to slow and/or stop. I brought it back to the dealer who supplied me with Bulletin #18-NA-035 - see here: https://www.tsbsearch.com/Chevrolet/18-NA-035

The bulletin states "some customers may comment that the transmission will not shift into overdrive range during cold ambient temperatures. This condition may be caused by the engine control system detetcting conditions that indicate the freezing of moisutre in the charge air cooler. When the control system detects the above conditions and the ambient temperature is eithe below 14 degrees F or slightly above 14 degrees F with high moisture, but not frozen, it takes the following actions: Requests a lower gear than normal (higher RPMs)."

Yes, the mornings have been "cold" but not 14 degrees cold. And it does not occur in the afternoon when its warmer. But here is my concern:

*Bulletin says ~14 degrees F, but it has occurred anywhere from 19F to 35F outdoor temps.

*Its not just at 70mph. I have noticed it stuck at 2+rpm when going 45-50mph with no downshifting. It "Settles" if I push highway speeds to 80mph, but if I dip back into 70mph range the problem returns.

*Finally, this vehicle has done the same morning commute for 4 previous winters without issue. This is a new occurrence starting directly after my recent service.

This all seems outside of the scope of the bulletin. What suggestions can I return to the dealer with? Could anything be amiss from the fluid exchanges or induction? Could a sensor be misbehaving somewhere?

Thank you for reading.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 21, 2024, 12:21 PM

Post #2 of 2 (457 views)
Re: High RPMs during morning commute Sign In

Sure, anything could have gone wrong while they were working on it. They could have damaged or left wires disconnected. They could have triggered a vacuum leak also.

The first thing to do is bring it back to the dealer that did the work and let them prove it wasn't them. You don't need to advise them how to do their job. They will resent that. Just give them all the history and symptom info you can and let them make a conclusion.



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