So I have done the icp sensor and the cam position sensor and just recently done e-fuel. I am still having a problem with a rough choppy idle. It only seems to be when the truck is warmed up. Seems to idle just fine when first started. Once it is warm then it starts idling rough and also the rpms will go up and down with the idle. At this point I am leaning towards maybe the ipr. Any help would be appreciated.

 

IPR is quite possible. Do you have a way to monitor ICP and IPR duty cycle?

 

Yes a buddy of mine has auto ingenuity

 

My truck has been doing the exact same thing you are describing, I mean exactly! It's been doing it for months. I tried everything, even replacing the IPR. No change. I have determined it's an injector or injectors. I don't know this for a fact, but that's all that's left. I'm getting new injectors and HPOP in a couple weeks, so I guess we'll see.

 

Im hoping its not any of the injectors. Mine are pretty new and when this first started I put it on the auto ingenuity and did the cylinder contribution test and all came up good.

 

My injectors were all good and I put new o-rings on them. The problem started a few months or so later. I have run 100 cc tests, and all pass.

 

My 97 would act just like this when you would start it. Didn't matter if it was warm or cold. It would stop as soon as I put the truck in neutral (automatic). Never could figure out the problem. Then the transmission went out. (I'm sure it wasn't related). New tranny, and we ran new ground wires from both batteries to the engine and body, and it hasn't acted up since. My friend told me that on some of the OBS trucks, he's seeing some problems with the engines, and he has determined that the ground wires are losing their connections causing power to fluctuate in the computers. In fact, as stupid as this sounds, they replaced the burnt out bulb in the brakelight that's mounted on top of the cab, and that fixed an engine issue. Check all the battery connections too while you're at it.

 

Well that sounds like something easy to start with so I will try it. Thanks for the help.