N14 celect plus erratic idle

[Luckyjayb]

(08-27-2022 )Signature620 Wrote:  Try disconnecting 1 at a time at the plugs on the side of the rocker housings. They never play up on a cut-out test. It's like the ECM goes into a really focused state when you start the test.

Did it both ways and all check out fine. I forgot to mention out of the 6, 4 were bad straight out of the box so I had to get two replaced. The main thing perplexes me is when I click on start to initiate the standard cut out test, the idle clears up and runs smooth as a bell. It runs smooth at 900 rpm’s and up. While look at live data, the ambient air pressure it correct but ambient air temp is stuck at 40 degrees Fahrenheit. I can’t for the life of me remember is the ambient air pressure sensor reads air temp as well bc if so, that could be my issue…..possibly. Thinking it’s in a colder temp than it really is. Intake temp is spot on as well. New coolant temp sensor and gauge, manual and the electric sensor, and both are reading correctly. Changed the fuel filter. I’ve done every trouble shooting step I can think out and even did all the Cummins troubleshooting steps and still no luck. The fuel pump was new when I did the out of frame on it 19k miles ago. Static timing is spot on for the CPL. Head gasket failure was due to the Birmingham Cummins dealer saying they couldn’t get the head gaskets and I had to use PAI, never will do that again, but other than that there hasn’t been an issue. Crossover tubes are good and sealed and no air getting in the system.