ccw55

Was driving this morning around town. Engine temp was about normal. Outside temp is about 30 f. Was sitting idling for about 10 minutes at 750 rpm. I could hear something clicking off and on and figured it was the block heater. The engine ideled up to about 1000 rpm on it's own. I noticed the volt meter gauge went a little under 14 volts. Normally it runs just past 14 volts. I bumped the go pedal and it went back to 750 rpm. The volt gauge went back to normal. I've noticed the idle has always been 800 rpm until today. Was wondering if anyone else has seen this. I don't think the 6spd has a high idle feature. This is my 1st diesel and also my 1st winter with it. No engine lights came on when it did this. What do you gus think. Sorry for the long post.
Thanks Wayne

linetrash75

my 98 does close to the same thing execpt it wont go down with a bump of the pedal I suspect its the iat sensor. haven't noticed that it effects the the volt gauge I will look next time this happens


Jed

Jeff in TD

Trucks with the 6 speed will bump up to 1000 RPM after a few minutes of idle with speed zero. Mine has never done that with the engine up to normal temp, though, but then I don't generally let mine idle that long.

I think it is the "use the cruise control to set fast idle yourself" thing that can only be set up with the auto.

The dip in voltage I'm sure would be the grid heaters.

I think your truck is normal, and if you don't have a choice about leaving the truck running that long, I'd let it bump to 1000. Might also be a good idea to drive it around before shutting down after a long idle in cold weather. I haven't heard of anyone bending a pushrod, but it might be good GP to burn the deposits off the exhaust valves...

VPI

Mine does that when it is cold out even if the truck is warm.

ccw55

Well I'm kinda glad someone else had this also. I'm not going to worry about it. This is the coldest we've seen here this year. Thanks for the replies. Merry Christmas to all.

bkrukow

That is normal. It has been around 0-15 deg here lately and every time I stop for more than 1 minute or so it will bump to 1000 rpm. The second you touch the foot pedals it drops back to normal. I always thought that the coolant temp had to be below 140 deg to get this to happen but it does it even with the temp gauge at full operating temp.(200 deg) It seems that the only thing that matters is ambient air temp.