97 Yukon sticking throttle?

[thezentree]

I've got a 97 Yukon (vortec 350) that has been acting strange lately. Now that it's starting to warm up, whenever I start the engine, it revs to about 1600rpm and holds there for 5-7 seconds. It didn't used to. Also, at low speeds (10-25mph) the throttle acts like it's sticking. As in, I've got ride the brakes to keep it from speeding up at those speeds. If I stop, the engine tries to power through the brakes for a second or two, then the RPMs drop to 600 or so and it idles normally. No SES light, the engine runs fine, and I haven't seen any noticeable change in fuel mileage.

Any ideas on why it's doing this?

 

[k20]

No help, but a couple of our old worktrucks do this, both of them have 300k+ on the clock though.

 

[thezentree]

I'm at 220k

 

[George_Pimpdaddy]

wonder if resetting the computer would help fix this?

 

[k20]

Im wondering something similar because as I said, both of our old POS' at work do this and both are high mileage. Have you ever changed the throttle cable zen?

 

[noJeepshere]

If the throttle pedal is smooth, I don't think the cable is to blame. Take it to a shop that has high end diagnostic equipment (maybe the University auto dept, that's where I go) and have them use a Picoscope on the throttle position sensor. I think that may be to blame. And they can use the scanner to see what the ECU is thinking.

 

[thezentree]

Nope, never felt like I needed to change the throttle cable. I don't know where in town would have a picoscope, save for the stealership, but my buddy's dad has a badass Snap-On scan tool that he'd run for me. I need him to take a look at my transmission anyway.

 

[noJeepshere]

Nope, never felt like I needed to change the throttle cable. I don't know where in town would have a picoscope, save for the stealership, but my buddy's dad has a badass Snap-On scan tool that he'd run for me. I need him to take a look at my transmission anyway.

That would work.