Engine/Transmission (1998.5 - 2002) Startup Problem (Maybe?)

[DaveN]

I've got 90K on my 2001. 5. Recently, with a cold start (the truck has been sitting overnight) when I start it, it acts like it's "missing" at idle, similar to how a gas engine sounds. The RPM's drop by about 40 or 50 RPM (I'm guessing based on the tach) momentarialy, about once per second. If I rev it up it's fine, but once it goes back to idle it starts again. Once I put it in gear and back out of the driveway, it's fine even if I put it back into neutral. If I start it warm it's fine, it only happens on cold start.



Any ideas? Something to be worried about or no?



Thanks in advance for any input.

 

[RJPotts]

No, that fluctuation on RPM is your grid heater cycling, or at least it should be.

Next time it happens, watch your battery gauge, it should kinda go up and down a little too.

I don't think its anything to worry about.

What is the ambient temp. when you start your truck for the first time?

-R. J.

 

[DaveN]

No, I don't think it's that, if it is it's cycling on and off about once per second!



Normally that stays on for a few seconds then swithces off for a few. But the RPM change is similar - maybe 40 rpm?



Recently ambients have been around 60 F in the morning here in Michigan.

 

[RJPotts]

I'm not sure then. When its cool but not cold my grid heater seems to cycle faster and for less time.

If thats not what's going on, I dunno.

If everything else seems fine, and there are no codes, I wouldn't worry about it.

-R. J.