I have a problem with my 03 randomly going to high idle. It almost acts like it is still cold and is idled up due to temperature. It usually happens after running at speed on the highway. When I come to a stop the engine will sit at about 1000-1100 rpm, but if I push the brake hard enough it will slow back down to normal 750 rpm. Once at 750 rpm it will stay there until I drive off, ie at a stoplight.

Truck is a 6 speed, and this happens with the quad box on any of the 4 settings, and also with everything unplugged and back to stock. I have found no evidence of fuel in the oil, and egts haven't changed appreciably from stock (little lower since the exhaust). Truck currently has 97K and other than this no problems.

Any ideas? (Please don't say injectors...)

 

...same here, it has happened about a dozen times throughout the past 2 1/2 years

 

I wonder if the coolant temp sensor is freaking out...

Possibly accelerator position sensor?

Any codes?

 

My 03 has done it since new. I posted that I thought it was from other parameters besides IAT but no one agreed. I'll get it when (I believe since I haven't measured anything) the engine is still hot after a run, when I have extra load on the alternator, or with my AC running at idle.

I'm not worried about it since it seems to be at good times when it does it.

 

No codes at all, sounds like you have the same exact thing going on Billie.

 

I have the same problem on our truck. It idles up to 1000rpm especially when I just start to accelerate then push in the clutch. If I push the brake in hard it idles down again. Would love to find a solution to it. No codes here either.

 

ding ding we have another winner my 4500 does it also

 

my 2003 also does the same thing that you guys are talking about.... did anyone every resolve this issue or find out what was causing this?

 

If the coolant temp gauge looks normal it may be an IAT sensor issue.

 

Is the sensor bad you think? Could I try to clean it or make sure it has good connection? It's very annoying.

 

Cleaning the IAT and MAP sensor is a good start.

 

My '03 has done it since it was new...but only does it during cold weather. I can drive it for hours at a time and, only if the outside temp is cold, it will randomly go into high idle. I hauled almost 25k lbs to New Mexico a few years back and after pulling for almost 10hrs straight I pulled over because nature was knocking on the door and almost instantly it went into high idle and the outside temp was around 40*. I know about the temp and high idle coinciding with each other, but pulling for that distance the engine should have no reason to idle up. I just quit worrying about it because like others have stated, if you tap the brake pedal it idles back down.

 

That's seems normal, all the coolant has to do is drop to 180° or lower and the ambient temp be cold (normally 32°, but a restricted air filter or slightly out of whack sensor can make the IAT colder) and at 2 minutes of idle it goes up to 1,000.