We've had our first extreme night in Kansas here for winter cold. Have had my 2005 5.9 now 2 months. I am aware of the diesel things that need taken care of during winter. I had a Chevy 6.2 and a John Deere diesel tractor.

Question........

I have the high idle feature programmed in where I can hit the cruise control and kick it up to 1100rpms and then manually up it to 1400 if I want. It works very well to warm up truck.

Tonight I did that and it was great. After some driving I made a stop of about 10 minutes and left it idle. I was just inside and could hear it running. On its own it kicked itself up to 1000rpms but it sounded like it was lumpin pretty good like it was running on a hand full of cylinders. Then after a short time it tripped back to idle (750).........I drove home. Heater is putting out enough heat to run you out of the cab. In the driveway sitting there it tripped the lumpy high idle again for a bit. Truck was about 1/3 of normal running temperature when it did this and the heater was putting out very good heat!

Is this normal? I thought the 2nd gen trucks only had the 3 cylinder cold idle feature?!?!?! Its automatic high idle sounds different then when I do the cruise control trick.

Normal or something doing a wierdo rama?

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Our 3rd gens will 3 cylinder high idle if it is cold enough.

Also know that if your truck is up to normal operating temp and you let it idle for a while (like the 10 mins you said) it will actually cool down if the air temp is low enough. The cooling system on these is VERY efficient when it is in good running condition!!

 

OK so its a 3 cylinder idle. I assume the computer just shuts off injectors?

Also how is 3 cylinders firing going to create more heat then 6 cylinders firing or is it more for emissions not being met due to cold exhaust then to warm the engine?

Been doing a lot of reading and it seems like there hasnt been a cut and dried what happens and why reason.......

Just trying to figure out what all is happening here and exactly why since there are 2 different ways it idles depending on if the truck or myself does it.

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