Q: I have a 2014 GMC Denali. Every time the rpms are at 1000, coming to a stop or coming out of a stop, something vibrates.

asked by on July 20, 2017

My GMC Acadia has been making a vibrating noise when coming to a stop or especially when coming out of one right at 1000 RPMs. I only hear/feel the vibration at 1000 and slightly at 2000RPMs. Also when braking the RPMs are fluctuating up and down and seem like they are getting stuck in a gear just a bit. Any ideas on the noise and fluctuating RPMs? Note, this is not a brake or wheel vibration. It appears to be coming from the engine.

My car has 42000 miles.
My car has an automatic transmission.

If the noise only exists when the vehicle is moving at the RPM values you cite, the vibration is probably in the drive train. If the vibration occurs in park though, again at the cited RPM values, then it is due to a rotating engine/transmission component such as the harmonic balancer or torque converter. There’s also a possibility there could be a motor mount defect. The RPM fluctuation on braking could be due to a transmission issue such as faulty valve body/shift solenoid controls. However, engine controls, such as the throttle position sensor, idle air control valve and so forth would be evaluated, too. To resolve an issue like this, you can request a vehicle vibration diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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