2000 Silverado Fast Idle And Delayed Shifts

[pletting.e]

In the past week my truck began shifting at a higher than normal rpm. At the same time I noticed the idle speed increased from its normal 500 to around 1000 rpm when decelerating and shifting into park before shutdown. At first I suspected an air leak from a cracked line or chafed hose but can find nothing. All plugs have been wiggle-tested and sensors checked for security. At 178000 miles I expect things to start happening but would like to know if anyone has experienced this problem so I can know where to investigate.

[98 Z71 SLT]

Fuel pressure ok?? At specs??

Carbon built up in throttle bore?? Carbon caked on Idle Air Control Motor?

Intake gaskets ever replaced?? At 178k you'd better believe those intake gaskets are split and causing air leaks...

keep us posted...

[jblakeney]

What about the DTC codes...... Sounds of your problem your check engine light probably is on.....

 

Jbo

[DMurphy]

I'm having that exact problem on my 2001. I have new plugs, wires, and just had the tranny flushed. It doesn't do it all the time and usually shutting the truck off and re starting corrects the problem for a while. I have codes for a bad oxygen sensor showing right now. The guy at the shop said I needed new catalytic converters. I am curious to see if anyone can help. I am at a loss.

[jblakeney]

I'm having that exact problem on my 2001. I have new plugs, wires, and just had the tranny flushed. It doesn't do it all the time and usually shutting the truck off and re starting corrects the problem for a while. I have codes for a bad oxygen sensor showing right now. The guy at the shop said I needed new catalytic converters. I am curious to see if anyone can help. I am at a loss.

 

Intake leak?????.... Whats your codes..... #'s?

 

Jbo

[DMurphy]

I'm not sure what the codes were. The guy at the shop just told me what they were. Not sure about an intake leak other than I don't hear anything.

I'm having that exact problem on my 2001. I have new plugs, wires, and just had the tranny flushed. It doesn't do it all the time and usually shutting the truck off and re starting corrects the problem for a while. I have codes for a bad oxygen sensor showing right now. The guy at the shop said I needed new catalytic converters. I am curious to see if anyone can help. I am at a loss.

 

Intake leak?????.... Whats your codes..... #'s?

 

Jbo

 

[desrtrat]

try cleaning your MAF and TB see if that helps..

 

good luck

[DMurphy]

I'll try that if it ever stops raining.

 

try cleaning your MAF and TB see if that helps..

 

good luck

[redvett]

I am betting on the TPS.

[DMurphy]

Wouldn't the position sensor act up all the time though? It's just weird that simply re starting the truck corrects the problem(usually). Anyway to test that sensor?

 

I am betting on the TPS.

[DMurphy]

Ok cleaned throttle body(very dirty), cleaned maf sensor, and installed new tps(potentiometer broke) I'll report back if it solved the problem. Only thing is now I have engine knock, I pulled the throttle body to clean and used crc throttle body cleaner, not sure what is causing the knock. Thanks for the help.

[pletting.e]

OK, As the original poster I just want to let everyone know that MY problem is solved. I was able to borrow a professional real-time engine analyzer and see the problem in action as well as read the codes. It told me the TPS was reading out of parameters on every start after going closed-loop and that the problem had been intermittent. The TPS had been acting up for some time apparently, just not as bad. My fuel mileage went back up to where it belongs as well. FYI, there were no other codes present. Thanks for all the suggestions, hope everybody else can find and fix theirs without too much trouble.

[DMurphy]

It was the TPS on mine. Have not had any more problems since installing the new one.

[vernons9358]

It was the TPS on mine. Have not had any more problems since installing the new one.

 

 

hey guy's,

found this post the other nite.. was having exact same problem on my 01 silverado,with 4.8... high idle in park,and delayed/hard shifts.. new tps sensor solved the problem!!! idles perfect,shifts as smooth as silk... thanks for the help. great forum!!!