(Pasted from other thread linked above....):
Reporting back on this. Haven't had the time dig into the harness nor ECM. Too many life things going on at the moment.
HOWEVER, some good news. I took the truck on some shake down runs. It drives ok, not perfect of course, but ok. I even loaded up the camper & drove to our summer camping spot without too much hassle. It's about a 30 min drive.
Truck warns up to op temp. CTS reads as it should. This is what I noticed on the drive, I was reading the scan tool along the way:
- Commanded desired idle rpm is 1000 rpm regardless of gear, or driving conditions. If I turn engine off, then restart it goes to 600-650 rpm, which seems more appropriate.
- The actual rpm at idle, in gear matches desired idle speed. However, in P/N is idles at 1500-1800 rpm. After the truck has been driven it slowly drops but only to about 1200 rpm.
- At the same time as this is happening, the IAC steps are 155. Really high. Spec is 5-30 steps at 525 RPM.
- Furthermore, regardless of gear, or driving conditions, IAC steps are always pegged at 155. Even cruising, 0% throttle, no AC, no lights or other loads. IAC reads 155.
Would this explain the high rpm at idle or high commanded desired rpm?
Another theory, could the ECM be opening the IAC Valve more, to add air, to try balance the rich fuel condition due to the Code 15, low coolant temp, aka add fuel?
What do the block learn numbers mean?
Ok my brain hurts. I'll see if anyone has anything to add. Cheers
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