Hummin Cummins

When the engine is warm and only at times after idling for a few moments my truck goes into a 1000rpm fast idle.<br><br>Funny thing is when the engine is warm it seems you can get it to idle fast if you bring the rpms up to 1300, lift off the throttle to leave the rpms drop and while it is falling you &quot;blip&quot; the throttle around 1100rpm and it will fast idle again.<br><br>------two questions Cummins----<br><br>1) Now...the question is...how do you get the engine to fast idle when it is cold? Mine lopes around 750rpm and will not rise unless I put my foot on the throttle.<br><br>2) Would also be nice to have a 1300 or 1500 rpm fast idle which (again I am going to Assume) DC or Cummins built into the rig already as it has the PTO port on the 6spd transmission.

wick

I do believe there is a module that you have to buy to get the idle to go higher.. i would assume that u would be able to reprogram the fast idle throught OBD-II port. Possible the dealer might be able to do it. Because I know when I had my camaro, with a power programmer I would change almost anything I wanted. Including the compensation for the larger gears in the diff, idle, rev limiters, stuff like that... <br>

Ladyjaine

Lady Jaine will go into a fast idle after starting and when idling if the temps are right. It the air temp is too low for her when I start her, she'll go into a fast idle. If her block gets too cool when I'm sitting and idling, she'll go into a fast idle. I don't do anything at all, not resting a toe on any pedal, brake, clutch or go. It isn't cold enough here for her to go instantly into fast idle on starting, it takes about 30 seconds to a minute. She fast idles at 'zactly 1000 rpm. <br><br>Jean

Lightman

It sounds like the same thing my tdi does. It could be for the same reason. When you blip the throttle or are under load, the EGR system isn't fully active, but once you settle to an idle, the EGR turns on, possibly introducing a slight load and reducing the idle. Not sure if it's the same on the cummins.

SuperGewl

The idle you are talking about is in fact controled by the computer. If you let it sit long enough in the right conditions it will go to fast idle, however if you hit the brakes or gas it will then idle back down to keep from harning the engine. I have the SO CTD and it does the same thing.<br><br><br><br><br>2003 3500 QC SRW Short Bed Larime<br>TT LSD 4X4

frogspit

The 6.0 PSD does the same . Start it cold,and it idles at around 650-700rpm . But, as it starts to warm it goes to about 1000rpm . Touch the accel or brake, and it drops to normal . If it's not totally warmed up , It'll go to highj idle after a bit . John

bulabula

I don't have my manual with me, but the criteria for the ECM to control the fast idle is something like this:

When the intake manifold temp is less than 32F, coolant temp is less than 140F, and the truck is stopped and you haven't touched the brake pedal, after two minutes the engine will idle up to a 1000 rpm idle to facilitate warm-up or to maintain temps.

If its really cold, something like 15F or below, the engine will immediately go to a 1000 rpm idle right after start up. Thats happened to my truck a few times and it is a little disconcerting to hear the engine rev up up to that fast idle. Its only happened to me when I haven't plugged it in, and that extra rattling makes it even louder.

There are aftermarket idle controllers you can purchase, as well as using an exhaust brake to help the engine retain heat.

Do a search on this site commencing in Nov, you will find much info/discussion on this subject. I believe the Tech Facts section has some info as well.