I have a 99 f350 and I can't get my truck to kick up the idle when it's cold out. There have been mornings in the negatives and still nothing. I replaced my egr tube and cleaned the exhaust pressure sensor. My exhaust back pressure valve opens and shuts while driving at slow speeds but not while at idle, but I don't know if that's related. I replaced the oil temp sensor with a ford motorcraft one. And I plugged my intake air temperature sensor into a buddy's truck with the same motor and his truck still idled up no problem. I'm stumped now, any ideas what's wrong?

 

I don't have the solution to your problem, but I want to follow along because I'm having the same issue. Albeit, mine is a '97 Powerstroke with an auto, but the issue is the same. No high idle regardless of ambient temperature.

 

You said you cleaned the sensor. Are you sure it's not toast? No oil leaks noticed from the valley area? That's were the valve is for the butterfly that closes.

 

Yes I cleaned the exhaust pressure sensor. The exhaust valve is shutting but only after I give it some throttle. I don't know how to tell if it's good or not other than that. I do actually have some oil in my valley but didn't think much of it I thought it could have been left over from when I did my Ipr valve. Does my exhaust valve operation have anything to do with the high idle?

 

Because the 95-97 trucks do not have the software capability to "idle up" when cold.

 

Manual or automatic transmission?

What is the PCM code? Some do not have the feature built into the calibration.

 

I've heard differently, but I'm not educated enough one way or the other to know which is correct.

However, on my dad's '97, he had one of these that was used to control the RPM and set the high idle manually.



Perhaps I need to find one secondhand and install it.

 

I have a 95 that idles up no problem by itself

 

It's an auto, I don't know what the pcm code is right now. But the high idle worked no problem last winter

 

Does the parking brake have to be engaged (and the dash light on) for the high idle circuit to work on the 7.3?

 

I believe eve only if it's a standard,

 

L99 zf6 here, and it's been years since mine would kick in. Not sure if gutting the pedestal, ebpv and bypassing the NSS(nuetral safety switch) if all/any play a role

 

Does the light on the dash come on when you engage the parking brake? If not it's most likely that switch.

 

Will have to take a gander. Got my daughters' pic in life right corner.

 

I thought the two worked together along with the pcm to get the truck to idle up when cold. I could be wrong on that, and will be corrected if I am. I am still trying to figure out all the sensors in these trucks myself. I too have one of the AIC (Auxillary Idle Conteol) modules in my trucks. To make it do it's thing you need the parking brake on. But the truck should still idle up on its one when it's cold, mine also woulds like a jet engine. People as me what my truck is doing, I just say it's preparing for takeoff