High idle, around 1500 RPMs

[Skippytj]

Hey y’all so I’ve been having a long term problem with a high idle mainly around 1500rpms sometimes higher and rarely lower, I have replaced the following items: tps, IAC valve, o2 sensors. I ran sea foam through the engine and cleaned my TB multiple times none of which have fixed the problem. I read that some people think spark plugs could fix it, I do not see how they would fix it but I have replaced the plugs little less than a year ago.. I suspect a vacuum leak which I had checked for ( not thoroughly) but does anybody have an idea what could be the problem. I live in southern Alberta where we have colder weather. Recently last summer I visited Moab and had no problems with high idle but as soon as I got back to Alberta Canada my high idle came back on. It has been like this for almost 2 years now and still no solutions. Correct me if I’m wrong but I think the cold weather may have something to do with it aswell?.

 

[AndyG]

Typically that indicates a lean condition, which means more air , so checking for an intake leak is sound . Also , remember when you go to Moab, that's American RPM, so its a lot less .

 

[Fouledplugs]

Vacuum leak, my .02. Seems as though you have unmetered air entering the engine causing the high idle.

 

[Chris]

Sounds like a vacuum leak to me.

 

[CharlesHS]

Hey y’all so I’ve been having a long term problem with a high idle mainly around 1500rpms sometimes higher and rarely lower, I have replaced the following items: tps, IAC valve, o2 sensors. I ran sea foam through the engine and cleaned my TB multiple times none of which have fixed the problem. I read that some people think spark plugs could fix it, I do not see how they would fix it but I have replaced the plugs little less than a year ago.. I suspect a vacuum leak which I had checked for ( not thoroughly) but does anybody have an idea what could be the problem. I live in southern Alberta where we have colder weather. Recently last summer I visited Moab and had no problems with high idle but as soon as I got back to Alberta Canada my high idle came back on. It has been like this for almost 2 years now and still no solutions. Correct me if I’m wrong but I think the cold weather may have something to do with it aswell?.

Two thoughts come to mind... with what you posted...
First... what temperature thermostat do you have installed and is your coolant sensor working properly; just wondering IF a malfunctioning sensor or a lower rated tstat may cause the PCM to ramp up the idle to warm up the engine.
Second... what is the elevation differences between where you live and Moab? Might this be a high altitude setting in the PCM or the MAP sensor responding in some way ?
IF my ideas are off base; then I would recheck for vacuum leaks.

 

[Skippytj]

Come to think of it my thermostat never showed full operating running temp it shows about 70-80 instead of 100. Where I’m at elevation is 2600m so I would suspect quite the difference in elevation. I ended up getting all new vacuum lines and still have a high idle

 

[Flivver250]

Recently I had a high idle and my rig threw a code for the throttle position sensor. I replaced the TPS, cleared the code and problem solved. Were the two related? Not sure but two problems were solved by one cure. I only had the issue for a few hours because I repaired it immediately.

 

[Flivver250]

If your gauge is correct, it sounds like your t-stat is stuck open. Put in a 195° F t-stat.

 

[Skippytj]

Typically that indicates a lean condition, which means more air , so checking for an intake leak is sound . Also , remember when you go to Moab, that's American RPM, so its a lot less .

Also I believe I have the 180 thermostat

 

[Bryanbones]

Check around the shaft on the throttle body see if it moves.it could be leaking around it causing the high idle

 

[Fouledplugs]

If your gauge is correct, it sounds like your t-stat is stuck open. Put in a 195° F t-stat.

A new thermostat might fix it, just as @CharlesHS had eluded to in his earlier post.