At constant speed (most any speed) the truck bucks and you can see it on the tachometer gauge?

ROCKSTAR_X3X

MEMBER
2012 GMC ACADIA
3.6L
V6
2WD
AUTOMATIC
150,000 MILES

However, when you switch on the cruise control, it straightens out. Throttle position sensor? Is that available for this vehicle? Whole pedal assembly? TIA

Tuesday, December 19th, 2023 AT 6:17 AM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
42,959 POSTS

It sounds like you have an engine misfire, the tachometer will jump if you have a misfire as well. The TPS is integrated into the throttle body, but we should run the codes, so we don't guess as to what the problem is. Let's start with this guide:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please upload videos of the problem so we can see what's going on and let us know which codes are listed.