1999 Tahoe LT

[Gwen Barnes]

I have a 1999 Tahoe LT with 260,000 miles. I have just started experiencing at kind of shift in the car while sitting at a stop light with my foot on the brakes. If not for my foot on the brakes, the car would go forward without me giving it gas. When it does this, the rpm needle kind of moves like I am accelerating. My car does have the original transmission in it. I have been told could be torque convertor. Any information would be very helpful, such as how serious this could be to my transmission and if how costly this could be.

 

[bigfootchiro]

I have a 1999 Tahoe LT with 260,000 miles. I have just started experiencing at kind of shift in the car while sitting at a stop light with my foot on the brakes. If not for my foot on the brakes, the car would go forward without me giving it gas. When it does this, the rpm needle kind of moves like I am accelerating. My car does have the original transmission in it. I have been told could be torque convertor. Any information would be very helpful, such as how serious this could be to my transmission and if how costly this could be.

Hi Gwen! Welcome to the forum! I’m assuming by you saying “rpm needle moves like you’re accelerating” means the needle is moving up in the RPM range. If so, that will not be torque converter. The TC is unlocked while at a stop. If it were engaging, your RPMs would drop and shutoff the engine, just like if you were to drive a manual transmission and engage the clutch too fast. However, you may have a vacuum leak, as this sounds like a potential lean condition at idle.

 

[Gwen Barnes]

Thank you bigfoot chiro, most helpful.

 

[east302]

Could be a sticking throttle, you might try cleaning out the throttle body and check for how well it opens and closes.

If you have a scanner, see what value the throttle position sensor is reading when it’s doing this.




Sent from my iPhone using Tapatalk

 

[RED TAHOE LS]

Hi Gwen! Welcome to the forum! I’m assuming by you saying “rpm needle moves like you’re accelerating” means the needle is moving up in the RPM range. If so, that will not be torque converter. The TC is unlocked while at a stop. If it were engaging, your RPMs would drop and shutoff the engine, just like if you were to drive a manual transmission and engage the clutch too fast. However, you may have a vacuum leak, as this sounds like a potential lean condition at idle.

Times two, erratic idle condition definitely vacuum leak.
David g.......

 

[Walrusmt]

Times two, erratic idle condition definitely vacuum leak.
David g.......

X Three on the vacumm leak. Also check the timing. On my Yukon the truck pulled against the break when the timing was too advanced - maybe a random condition, but when I corrected the timing the problem went away.

 

[Gwen Barnes]

Could be a sticking throttle, you might try cleaning out the throttle body and check for how well it opens and closes.

If you have a scanner, see what value the throttle position sensor is reading when it’s doing this.




Sent from my iPhone using Tapatalk

Would most small auto repair garages have a scanner or do I have to go to a dealership? Thanks so much for your input.

 

[east302]

Any repair shop would have one, but at that point they’d be charging you some minimum labor charge just to look at it - maybe an hour. It may then just be easier to have them look at it and see if they can figure out what is wrong.


Sent from my iPhone using Tapatalk

 

[Gwen Barnes]

Any repair shop would have one, but at that point they’d be charging you some minimum labor charge just to look at it - maybe an hour. It may then just be easier to have them look at it and see if they can figure out what is wrong.


Sent from my iPhone using Tapatalk

Does a scanner show most things going wrong with an automobile (sorry for sounding like an idiot)?

 

[east302]

It will pull trouble codes and give readings of various sensor outputs, so it’s more for diagnostics than anything. It won’t say “fix this part” unfortunately.


Sent from my iPhone using Tapatalk