idle changing
 

I was working on the truck today changing the front hub (another poast). I started the truck and it ran fine. As it idled there the engine slowly reved up in steps of about 50 rpm increments to about 1250 rpm. Total rev up time from 800rpm to 1250 rpm was about 20seconds. Once I touched the throttle and reved it up past 1250 and back to idle, it idle back at about 800rpm. Then it slowly sped up again and kept doing this for about 10 minutes. After that it ran fine and idled at about 800rpm like always. It didn't run on three cylinders like I have read about it just reved itself up to a high idle. It wasn't that cold today no colder than it has been about -2*c. It has been at my friends place for less than a week not being driven, but that shouldn't make a diffrence should it. Is the truck doing what it should or is it doing what ever it wants?

High idle comes on at a certain temperature, do not remember temp.

The three cylinder shut down comes on at a lower temperature, so it could have been cold enough for high idle but not cold enough for three cylinder shut down.

It could also be the APPS going bad but I would lean more to the cold high idle as the culprit.

Shawn
I used to have the high idle work on my truck and it used to step up like that, that sounds about right. For whatever reason it hasent done it for a few years now? Maybe it needs a reflash or it hasent been out in cold enough weather? Hows the WB replacement going? Are yeah up and running? Hope all went well :)

Paul

The truck is on the road again. The idle thing has only happened the one time so I will keep an eye on it and see if it does it again and note if there is a patern. The wheel bearing well it's all is in another post. I wouldn't wish that job on my worst enemy, at least the way mine was. I have had to get a lot of tough stuff apart but that was a lot of work. It looks like I might be doing ball joints soon as well.:mad:

Might want to pull out the IAT (intake air temperature sensor) and clean it with brake parts cleaner (brake cleaner leaves no residue). I believe that is the sensor that the computer uses to go into normal idle, high idle, or 3 cylinder idle.

Ratsun, the above method will probably help you out, even pick up some better mileage too.