High rpm problem.

[Venom]

I got a 2001 Chevy tahoe 5.3 4wd. Been having this problem for sometime and it’s gotten worse overtime. When ever I drive a decent amount maybe 10-15 miles when I put it in park, the rpms kick up anywhere to 1000-1500. Sometimes it’s a hard start and Rpm’s kicks up when going to reverse to drive or drive to reverse. When driving at idle the Rpm’s are usually at 800-900 I don’t have any codes at the moment. I’ve replaced iac, temp sensor, plugs, wires cleaned throttle body, cleaned maf. Any suggestions would be appreciated.

 

[Fless]

Possible vacuum leak? Have you looked at your fuel trims?

 

[PNWYukon]

First thing I thought would be vacuum leak somewhere, but you need to look at some data, like @Fless said.

 

[Venom]

First thing I thought would be vacuum leak somewhere, but you need to look at some data, like @Fless said.

I’ll do that, though I have no idea how to read data so I’ll have to do some research or post my data here.

 

[PNWYukon]

You need a pretty good scan tool to read live data on these rigs. Most brands of scan tools are self helpful or there will be a video about it somewhere.

 

[Doubeleive]

if you over 160k I would consider just replacing the maf cleaning can only do so much, iac could also be funky, finding an exact replacement is near impossible you might have to look for a clean used one on ebay or at your local junkyard, another thing to look at is the map sensor, if you have tech2 or a scanner that can show live data that might help narrow it down.

 

[Venom]

if you over 160k I would consider just replacing the maf cleaning can only do so much, iac could also be funky, finding an exact replacement is near impossible you might have to look for a clean used one on ebay or at your local junkyard, another thing to look at is the map sensor, if you have tech2 or a scanner that can show live data that might help narrow it down.

I have around 151k, my maf g/sec was 9.25 at idle. And I can only get voltage for my map which was 1.31 at idle. My iac position was also at 0. I was sitting around 820rpm at the time

 

[Venom]

I have around 151k, my maf g/sec was 9.25 at idle. And I can only get voltage for my map which was 1.31 at idle. My iac position was also at 0. I was sitting around 820rpm at the time

 

[Doubeleive]

@swathdiver @iamdub how do those numbers look

 

[swathdiver]

@swathdiver @iamdub how do those numbers look

Not sure. If memory serves, in my 1980s cars, we had to calibrate the IAC motor to help control the idle. High idle like that is usually a bad MAP, or MAF or vacuum leak. MAF was the usual culprit back in the day.