Engine/Transmission (1998.5 - 2002) uneven rpm when cold

[tmacod]

When I drive my truck cold (around 35 or less, I know that is not cold) it seems to have a slight RPM jump. It is a manual and if I am driving at about 1600 RPM holding throttle steady the truck will feel like I am hitting a head wind and you can hear motor pull slightly. It is a very brief event. Once truck warms it is not noticed. My fuel pressure never changes and I run Stanadyne in every tank. Any suggestions?

 

[DIESELWRKS]

I get a slight reading diff also in cold weather on my 02 6spd the grid heaters will keep cycling and draw your power untill a certain temp when idling when my grids kick on my idle rpm needle does bounce alittle.

 

[Joe Mc]

My thought too was the grids kicking in. I think they are supposed to stop kicking in after a certain speed, like 15 mph - although I could be wrong and/or that could be "just" for an automatic?

 

[tmacod]

thanks that makes sense.

 

[tmacod]

alright so still trouble shooting the drag on my motor when it is cold. batteries, connections and grounds have all been checked/cleaned. i still believe it is heater grid but would like to make sure. can someone tell me how to disconnect for a few days to see if it makes a difference. I have read in past to leave solenoid connected to reduce error codes. i am not sure if this is true.



travis

 

[JCyrbok]

Is it doing it when the defrost is on? Mine acts like that when the defrost is on as the A/c compressor cycles during the defrost setting. If I am sitting at a light it is almost like a brief stumble, but is always coincides with me hearing the A/c clutch shut. I dont however think that I have ever felt it running down the road, only while at idle,



Just a thought



J-

 

[tmacod]

tried with defrost/ air off this am and still present. when it happens it is a solid pull on the motor like someone just hooked and unhooked 4000# to my truck. lights will also dim briefly.

 

[champspa]

ac compressor runs in defrost mode

 

[JCyrbok]

tried with defrost/ air off this am and still present. when it happens it is a solid pull on the motor like someone just hooked and unhooked 4000# to my truck. lights will also dim briefly.

Humm with the lights dimming it def seems like it might be the grid heaters then. Maybe a bad relay or temp sensor that keeps em running while you are running down the road. I think that they are set to kick off at 15-18mph regardless of temp.



J-

 

[VHolloway]

Try a high amp alternator like 210 amp these truck needed one rite from the start. The grid heater really pull it down