My mom's truck started idling rough with a P0089 code. Using my oscilloscope, the PWM pattern going into the FCA looked PWM-ish and the rail pressure sensor signal looked valid; at idle I could see the pressure dip momentarily whenever the idle dip.

I decided it was the FCA on the back of the CP3, so I ordered one and changed it.

First, when I had the thermostat cover off, the front thermostat stayed in the cover and I managed to drop a small 1/4" wrench down the hole. It looks like that hole goes down a steel tube, through a flange, then down to a big hose that loops under the engine back into the radiator. I rodded out the steel tube, took off the big radiator hose and looked through the flange that connects them, but I couldn't find my wrench. Is my schizophrenia getting worse or did the wrench go somewhere I didn't look? I believe with all my mind that the wrench fell down the front thermostat hole, but everything I believe is routinely proven to be wrong and I don't have much faith in my memories anymore. I don't see where else it could have gone after it fell down that hole?

Second, when I put the new FCA in the pump, I had to compress it in by tightening it odwn with the three screws that hold it in. Is that normal or does it mean I used the wrong FCA?

Third, after I got the new FCA installed I took it for a test drive. It now idles smooth, but when I put it in neutral (2001 automatic) at freeway speeds the idle stays at 2000 RPM instead of going to the normal ~600. It's also slow and smokes lots of black under acceleration, and now I'm getting a P0193 on top of the P0089.

 

https://www.dieselbombers.com/chevro...l-testing.html



hmm, cp3 is a more probable cause for the problem your having. oh btw the fuel control acuator is amperage controlled. it is PWM too.

 

your wrench could be ummm


what in the hell were you doing with a 1/4 wrench anyways