My '05 kicked up to a high idle of 1.000 RPM today after a few minutes of idle after a 40 mile trip in 14 degree weather. What is the purpose of the high idle??
I noticed it really dropped the temperature of the coolant gauge.
Thanks.

 

It warms the engine up faster is all.

 

I started mine last night after being at a family get together where I was unable to plug her in. It was 15degrees outside. She started right away, but the cold made her sound labored a little. After a few minutes, idle kicked up to 1000rpms. Why didn't it do this immediately? Is there a way I can do it?
Also, I was able to hear/see the grid heater cycle on and off well after it was started.... is this normal?

 

High idle prevents wet stacking (cyl washdown)

 

All perfectly normal.
It doesn't go into high idle right away because it needs to make sure that it is really cold enough, and it's not getting a false reading from one or more of the sensors.
Fer instance, one of the sensors is the coolant temp, it takes a while for the coolant to circulate and the reading to steady out.

Grid heats take a lot of juice, you'll hear the relays kick in, engine will sound different, volt meter will dip way down and exterior/interior lights will dim.

phox

 

Cummins also have issues with the valves and push tubes getting gummed up with unburnt fuel after prolonged low temp idling, and end up sticking or getting bent. High Idle gets everything up to operating temp faster, and keeps it there to reduce the chance of this happening.


phox

 

Thanks for the replies everyone!! Much appreciated!!

 

get a bullydog downloader and the high idle is automatically enabled

i just hit cruise then set whenever i go in somewhere, even if the truck is warmed up. that way it stays warmed up and doesnt cool down or something if its really cold.

 

I just took my truck in for service the other day...I thought they reprogramed the ecu to do this? I never noticed that it idles up does it only do this at certain temps? Although this is the coldest weather we had since I purchased the truck back in July

05 2500

 

You do not want higher rpm's immediately at start when cold. Need a couple of minutes to get the oil moving, then increase. Do not want to rupture a seal anywhere or make a scuff.

 

Very good point AaronT. Now it makes sense to me why it started, then after awhile the idle kicked up.... I feel stupid for not getting it sooner..