High idle at start

[nsmith]

I’m at wits end with this. So, NEW TPS, IAC, MAF with screen delete. When I start it and while driving I’ll get a high idle. When I’m slowing I can feel the high idle pushing the vehicle even though I’m trying to stop. Any ideas? Recommendations?


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[Livebai8]

I’m at wits end with this. So, NEW TPS, IAC, MAF with screen delete. When I start it and while driving I’ll get a high idle. When I’m slowing I can feel the high idle pushing the vehicle even though I’m trying to stop. Any ideas? Recommendations?


Sent from my iPhone using Tapatalk

Ive had high idle few times...im about to replace the tps and the iac valve myself but it's mainly a low idle at start sometimes...if i prime the key several times it starts just fine but high idle sometimes. I still gotta replace my ignition switch too

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[OR VietVet]

Have you checked for a vacuum leak? Have you checked the throttle plate? Have you checked......etc? You did not give any rig info so right now I am just seeing what sticks.


We recommend that you put all your rig(s) info in your signature so we all don’t have to guess at year, make, model, engine size, trans, rear axle locker…….etc. While you may have posted pertinent info in your first post, you may forget to do it again and the info is needed by us anyway. Makes it way easier on all members that attempt to help, to have that info right up front. It is also recommended that you take a pic of your RPO codes, on the inside cover of the glove box, and post that image in your signature. All this info will greatly help those that will try to help with a problem.


If there is any other info, like upgrades, mods or recent mechanical/maintenance work done, that would be helpful in any post as well. Too many times a question is asked by the poster and after about 10 responses we find out that the poster has done recent work to attempt to fix the problem or work that was done that SEEMS not related to the problem.

 

[nsmith]

I updated signature, thanks for that recommendation. There’s not much vacuum on an 02 is there? Those lines are the only thing NOT new under the hood, lol.


02 Yukon XL
Everything under hood is new~newer trans
CAI~headers ~flowmaster~billsteins~moogs
20’s on Nittos

 

[nsmith]

Bit of an update. Reset the IAC (push pedal to floor slowly let up while key off, ignition off) then started and it calmed down. Still get high idle with slow calm after first drive. Now, with AC on and at idle in park, AC kicks on/off rapidly, which in turn messes with idle and the turning on/off of electric fans. Does fine while driving out in traffic. Ideas?


02 Yukon XL
Everything under hood is new~newer trans
CAI~headers ~flowmaster~billsteins~moogs
20’s on Nittos

 

[OR VietVet]

What happens if you unplug the coolant temp sensor? Not the sender for the gauge but the sensor for the open and closed loop info to computer.

 

[Tonyrodz]

What happens if you unplug the coolant temp sensor? Not the sender for the gauge but the sensor for the open and closed loop info to computer.

Would the coolant temp sensor cause a cel? Assuming that was the cause? Also--if that was the issue, would it still register the temp on the factory gauge?

 

[OR VietVet]

The SENDER is for the gauge. The SENSOR is for the computer. They are 2 different items. An unplugged sensor can send a code but if it is failing it typically doesn't unless there is an open in the circuitry or the damage caused by the sensor to something like the O2 sensors and cats can set the code.

The sensor is like the choke for the fuel injection system.

 

[Tonyrodz]

The SENDER is for the gauge. The SENSOR is for the computer. They are 2 different items. An unplugged sensor can send a code but if it is failing it typically doesn't unless there is an open in the circuitry or the damage caused by the sensor to something like the O2 sensors and cats can set the code.

The sensor is like the choke for the fuel injection system.

I'm having a similar issue with my van, so just trying to gauge some expert knowledge. Great info, thx Ron

 

[OR VietVet]

Anytime.

 

[nsmith]

What happens if you unplug the coolant temp sensor? Not the sender for the gauge but the sensor for the open and closed loop info to computer.

I’m ok at mechanics but that went, maybe the terminology, above my head. Is it just the fuse lol?


02 Yukon XL
Everything under hood is new~newer trans
CAI~headers ~flowmaster~billsteins~moogs
20’s on Nittos

 

[Tonyrodz]

Just in case that's the issue. Here's a vid on it. Super simple.

 

[OR VietVet]

Thanks Tony.

GM can change things but that location used to be for the sender and the sensor was up by where the thermostat used to be on top of the intake.

As I look at RA for this they list a sensor but no sender. The two may now be all in one design. If you read the description though it talks about how it communicates with the computer to adjust air/fuel as it warms and even effects timing.

 

[Tonyrodz]

Thanks Tony.

Anytime

 

[nsmith]

All my issues are with AC on. Would the sensor be messing with computer when AC gets kicked on?


02 Yukon XL
Everything under hood is new~newer trans
CAI~headers ~flowmaster~billsteins~moogs
20’s on Nittos

 

[afpj]

What is a screen delete? if you remove the screen from the MAF that changes air flow characteristics. You also mentioned electric fans which are not standard on an '02 Yukon. Did you have someone do a tune on it?

 

[nsmith]

What is a screen delete? if you remove the screen from the MAF that changes air flow characteristics. You also mentioned electric fans which are not standard on an '02 Yukon. Did you have someone do a tune on it?

It was an eBay kit that hasn’t given me any issues in 3+ yrs. I have a temp probe that tells them to kick on and then wired into AC when AC kicks on they kick on. Screen from MAF is deleted. But no issues in 2+yrs I’ve had that. My issues seem to be with AC on only. I’ve done some reading up and replace temp sensor and see if that makes a difference.


02 Yukon XL
Everything under hood is new~newer trans
CAI~headers ~flowmaster~billsteins~moogs
20’s on Nittos