I was rooting through old posts on here and came acrossed the High Idle topic. Well, I always thought my truck had high Idle ( 05' 6-speed ) whenever I let it idle for a few minutes the RPMs will jump up a couple hundred and stay there. I always thought that was high idle.

Now, after reading the treads about high idle, I am confused. Apparently, manual tranny's do not have the high idle option and even if it did you have to set it with the cruise control??

Someone school me on this subject please. And, if my truck is not high idling on its own, why do the rpms jump up after a few minutes????

Also, what exactly is the purpose of high idle???

 

i have an 04.5 truck with auto. when the outside temp reaches a certain temp (around 30 degrees) the truck will automatically bump up the rmp"s in park. truck also has a manual high idle feature that was enabled at the dealer. if i am in park and hit the cruise button, along with the on button (i believe) it will also bump the idle up to 1000 rpm"s.

 

The purpose for high idle is to avoid a condition called wet stacking. An engine at idle does not create high enough cylinder temps to atomize the entire amount of fuel being injected into each cylinder causing the unburned fuel to mix with, and wash down the oil from the cylinder wall, thus dilluting the engine oil with diesel fuel and causing excessive engine wear. All class 8 and 6 engines have had the ability to raise the idle through the use of the cruise control since their conversion to electronic engine controls, and most manufacurers recomend a minimum of 1,000 rpm for extended or prolonged engine idle periods. On my 06 automatic truck, when the temps are low enough it will idle up to 1000 rpm after 3 minutes at base idle, or I can engage the high idle by pressing the cruise button on then pressing the resume/set side, it will instantly jump to 1,100 rpm, if I continue to hold the resume/set button the engine rpm will continue to rise to 1,500 rpm and stay there until I disengage the cruise with the on/off button, or step on the brake.


Hope this helped,

Tim

 

^^^^^^^^^What he said. It can't be explained much better.

 

THANK YOU !

So, my manual 05' does have a high idle. It comes on automatically and I can not do this manually with the cruise control like on the automatic tranny's.

I think I got it now. ( i never claimed to be the sharpest tool in the shed )

 

There are several threads on here about how you can have your manual set up to use the cruise buttons as well. It is not as simple, or inexpensive as having it done on an auto.

 

On the manuals it's a $12-$20 wire that you plug into the ecm and ground somewhere. A real simple mod that doesn't take long to do. After you've added the wire you take it to the dealer and let them flash it to enable the feature and you're all set to go. Your truck will go up to 1000 rpms automatically but if you had the mod you could set it anywhere 1100-1500 with the cruise control. It's handy for defrosting faster in the winter, cooling down in the summer, or if you sleep in the truck idling all night preventing the wetstacking.

 

Thanks for the correction on the price part, Junky.(I thought I'd read awhile ago that it cost a bit.) I knew there was a way of getting it done- just didn't know how!