no response to throttle when cold

[cfarrar]

A friend's 2003 (HO, 6-speed) will do nothing but idle for about 30 seconds after being started on cool or cold mornings. He tells me that if it has sat overnight and he starts it on a morning when it's less than 40 or 50 degrees (F) it won't respond to throttle for a while, then usually runs normally. It reverted to this behavior for a few seconds when he started to move it while still cold once. I guess that in that case he started it and had the problem, but it then responded to throttle for a little bit before falling to idle again for a while. It has set engine code P0477, "exhaust pressure control valve low". He doesn't have an exhaust brake on the engine.

 

[cfarrar]

Doesn't anybody have insight into this?

 

[CPittman]

Could be the APPS or "accelerator pedal position sensor" or "throttle position sensor". It's a kind of rheostat on the side of the engine (under that big plastic hood on the driver's side of the block). My truck exhibited the "dead pedal" phenomenon while driving on the road - it would drop out with no throttle and then cut back in. The higher mileage '03s and '04s are starting to see failure of this part now. The APPS on my '04 failed at 191,000 miles.



If that is the problem, you can get a replacement from Cummins or from Mopar, however, the Mopar part comes pre-calibrated on the bracket so it's "plug-and-play".