Racing at idle on 2003 5.9

[hitchjnj]

I'm having a problem that seems to be worsening. My truck will idle fine when cold starting at normal idle and then after a minute going up to a fast idle until it warms. Once it is warm if I am idling it will kick up from a normal idle(750 rpm) to a high idle(1100 rpm) and at times when I come to a stop it will never kick down to the normal idle just stay at the high idle. Any suggestions or thoughts?



J. Adams

2003 3500, 6 speed manual, dualie

2004 Hitchhiker 31. 5 LTK

 

[TboneMan]

APPS (accel. pedal position sensor)? I had a similar issue, unexpected warm high idle while going through a toll booth, that I didn't think much about until I got stranded on the highway about 20 miles down the road with no go-pedal.



Boy was that a bad trip!

 

[DE Jeeper]

My truck started doing that a while back too. When I loaded the Smarty it took care of of it. I think it is some programing glitch. I tried to get the dealer tech to fix it, but he looked like a confused dog, head tilt, when it high idled. If you hold the brake down hard does it go away? If so it might still think it is in cold start mode. Maybe the air temp/barometric press sensor on your intake is going bad. I have a new one coming for my truck because it is throwing a p107 code and defueling at 1900 rpm. It used to occasionally trip that code, but now I can not clear it. Maybe this stuff is all related some how??????



Aaron

 

[CoastyAV8R]

Mine will do the high idle thingy if I roll up to a stop sign in neutral and coast to a stop on occassion. If I put it in gear and start to release the clutch it goes back to normal. My 04. 5 CTD did the same thing and all the research I did was that it was just part of the software so I don't lose much sleep over it. Mine doesn't start to high idle when it's just sitting idling for an extended period of time though when it's already warm though. DE Jeeper's suggestion seems plausible but how do you check that????

 

[hitchjnj]

Thanks for all the help. Right now it is just a major irritant but I wanted everyones thoughts as I pull a big 5th wheel and after being broken down last month when I lost the lift pump I really don't want to go through that again. The truck now has a 166000 miles on it and I can use all the help I can get.

Tanks again.

 

[DE Jeeper]

I think you are fine a bunch of trucks have this issue as they age. You can try putting a new air temp/barrometric sensor in and see if it fixes it. Its around $50-60 from the dealer. Are you getting any codes? My truck as always got the "bad fan" code, but it opererates correctly and I am spending $350 for a new one. I believe that part of the harness is interconnected and thus throws unrelated codes.



Aaron