When I crank my truck and it goes to high idle while still cold it sounds like it is missing/surging. It is not the grid heater kicking on you can hear the engine get pulled down a little when it kicks on and it stay on for a bit. This surging appears at high idle 1000 rpm and I have only noticed while cold. The surge may be 100 or less rpm but it is constant you can hear it and see it in the tach. I don't think my truck did this last year. I don't want to go to the service department again unless I just have to. Any input on this would be great.

 

Does it go away after a minute or so?

 

Is oyur defroster on? Could be the AC compressor cycling on.

 

Are you saying you are seeing this after the grid heaters have stopped cycling? You may want to turn on an interior light to watch for dimming when the heaters cycle. If you have the defroster on, it may be the AC cycling too.

 

Yes it goes away when the truck gets up to temp. Yes the defrost is on but does it with it off as well. I would hope the ac does not cycle that quicly. The surging I am talking about is not every 10 second or so is a constant changing up and down that can be seen and heard. It sugres up or down every second if not quicker.
Thanks

 

It sounds like the fuel pulses from the injector pump which seem to be more pronounced when the truck is cold. Mine does it and has since new. No problems yet..