Engine/Transmission (1998.5 - 2002) fluttering idle

[twheat]

Hello,



I have a noticed lately the truck's rpm needle acting a bit strange. The needle will flutter up and down slightly at idle and when crusing with the cruise control on. I am just wondering if this is a normal thing or is it APPS related? I have read a few threads that suggest it could be the APPS going bad. No codes stored. Thanks.

 

[KKlingbeil]

My opinion is that it is pretty normal. If it is flucuating 100rpms or so, then I would be concerned, but just very slight movement is normal.

 

[JLandry]

My opinion is that it is pretty normal. If it is flucuating 100rpms or so, then I would be concerned, but just very slight movement is normal.

Agreed.



Keep in mind the analog engine rpm gauge is digitally driven with only a certain amount of minimum resolution. When the input engine rpm falls right on boundary between two segments resolution output, the gauge needle fluctuates back and forth slightly as it tries to make up its mind which side of the resolution to be on. I see this same behavior in my Isspro EV2 gauges. The needles constantly hunt ever so slightly as they update in response to their inputs.



John L.

 

[twheat]

Ok sounds good. I figured it was normal. I also noticed it only happens when its cold. Once its warm its steady. It really flutters when the grid heater is going.