99 Tahoe Maintains speeds even when throttle is "returned"

[tapp1]

I had a 98 Sonoma that did the same thing. I fought with it and never could figure it out. I ended up selling the truck to a friend. He replaced the gas cap and that fixed the problem. Let us know if that works for you also.

If that was the case it probably was a vacuum issue which caused a high idle thus keeping the car rolling. Just a thought....

 

[Motopsycho]

The Sonoma had a high idle until it came to a complete stop, at which time it would return to normal. While rolling in N or the clutch in, it would idle at 2000-2500 RPM.

 

[SunlitComet]

Sorry I don't see a gas cap doing that. Starvation yes. high idle no.

 

[96ProCompTahoe]

couldn't you disconnect the cruise throttle cable to see if thats causeing it or will that throw a SES light?

 

[tapp1]

I should also add the spring on the throttle body seemed to return fine as I slammed my fingers in the butterfly cleaning it..

 

[BattelWagun]

I'm gonna put my money on the throttle cable. Cant really be TPS because it happens at speed, when the TPS is inactive.

And I don't see a gas cap doing that either, seems like a leak causing a very lean condition...

 

[SunlitComet]

you can disconnect cruise cable from throttle linkage and even unplug module with out any warning lights it simply will just no work that is all.
Tps is always active but it does not actuate just gives feed back. As for actuating the only other thing that can do this is the Idle Air Control actuator. A good scanner can read it desired position. Also from alldata "The IAC valve affects the idle characteristics of the vehicle. A fully retracted valve allows too much air into the manifold causing a high idle speed. A valve which is stuck closed allows too little air in the manifold, causing a low idle speed. If the valve is stuck part way open, the idle may be rough, and the idle will not respond to engine load changes."

 

[tapp1]

unhooked the cruise cable, doesn't seem to make a difference. I put the vehicle in neutral and it continued to roll. I guess the Tahoe is just a roller.

 

[SunlitComet]

roll at the same speed with tranny in nuetral? Oh das not good.

 

[tapp1]

roll at the same speed with tranny in nuetral? Oh das not good.

It does slow down eventually. Just rolls really well. I am not used to this thats all. I am curious what the rear-end gears are.