2000 GMC Sierra 1500 Idles High and Jerks into Gear

patrickirving94 · October 24, 2013

Hi,

I'm having a problem with my 2000 GMC Sierra with 117k. It's idling in park at about 2200 and when i put it into drive it bucks hard. I need to figure out what is causing this so I can fix it before it damages the tranny. Also, when i'm driving and push on the brakes it's like the engine is still pushing it forward. Any advice is appreciated.

rjgti · November 3, 2013

check your thottle body for carbon build up, and cruise and throttle cables are not too tight.

efritz · November 4, 2013

There is a good chance it may be your TPS (throttle position sensor) It causes erratic idle speeds and rough shifts, especially the 1-2 shift. It lives by the alternator on the throttle body and is round. To check it (if you have over 100k just replace it, who cares it's only like 35 bucks) put an ohmmeter on the leads and check for smooth progression as the throttle is pressed, it is really just a potentiometer-type resistor. You may have to remove the alternator to replace it.

good luck!

grossm79 · November 13, 2013

TPS is definitely worth the check, so is stuck or carbon jammed throttle plate- I would also take a look to see if you have a big vacuum leak. Sounds like it is getting a ton of air somewhere, either around the throttle plates, through a leak, or because of a stuck Idle Air Controller. (IAC)

Good luck with it!