Engine/Transmission (1994 - 1998) Low idle when cold

[McLaughlin]

I just recently noticed that when the temps get into the 20's, my truck only idles at about 300 rpm for the first minute or so. Afterwards the idle increases to about 750 and stays there. Seems like it always used to idle closer to the 750 number before the last few weeks. Is this normal or does anyone know what might be causing the problem?



Engine is not producing any smoke at start up.

Engine seems to crank a bit more than it should but not excessive (cranks maybe 10 or 15 revs)

Seems to have plenty of power when warm.

Fuel economy seems OK.

Lift pump replaced 700 mi ago.

Injectors tested 700 mi ago.

No codes.

 

[Signal73]

Mine does the same thing. Dont know what causes it because it idles where it should after a minuite or so. Only when its real cold like yours. I just hold down the throttle for a min. or so to bring it up to 750 after that I let off and it and it stays where it should.

 

[mhuggler]

Same thing here too in my 94', it only takes about 30 seconds and it idles normal then. You should always warm the truck up for a good 2-3 minutes before driving anyway, maybe more when it's that cold out.

 

[Joe G.]

If you warm it up you need to have a way to keep EGT up. Best to go as soon as it is running smooth. Take it easy until you have some a little warmth on the temp gauge. The most wear is when the engine is cold. The way to keep it cold as long as possible is to idle it. An exhaust brake helps a lot to increase EGT. Or a fast idle kit.

 

[Howard Durand]

I have quit being positive about anything but I think that if you are warming up with the defroster on, the AC is running too.

 

[McLaughlin]

I did a forum search after posting the question. Looks like a lot of folks have seen low initial idle speeds on these trucks. Seems pretty normal; just hadn't noticed it before.