Luke_IDI
Registered User
I am trying to diagnose a crank no-start on a 2003 E-350 7.3. I have another thread detailing the convoluted diagnostic process here if anyone is interested: https://www.oilburners.net/threads/slow-crank-after-possible-overheat.92706/
This new thread is for clarification on the simple issue of testing my ICP sensor.
When cranking, IPR duty cycle goes to 60-65%. ICP correspondingly climbs and climbs to 3700 psi.
Is this IPR reading a real or inferred reading? I have read that the PCM will disregard the actual ICP reading and report an inferred value if the actual ICP reading is vastly different from the desired. If this is the case, one could see high ICP on the scan tool while still having low ICP.
I have seen it suggested to monitor voltage at the sensor itself. I back probed the wires and interpret the following:
Black with white stripe = ground
Gray with pink stripe (?) = 5v ref
Blue with green stripe = signal
I get 5v KOEO at the reference wire. I get 4.6v at the signal wire. According to a chart I found, 4.6v is pegged high. There is no change in the signal wire voltage when cranking. Therefore I infer that the sensor is bad, and the PCM is making up values for ICP.
I hope someone can corroborate my understanding so that I can feel confident spending $150 on the new part.
If the sensor is indeed good, if anyone has an explanation of how it works electrically speaking, and any other thoughts on why the injectors are spitting no oil (not firing, I assume), they would be most welcomed.
This new thread is for clarification on the simple issue of testing my ICP sensor.
When cranking, IPR duty cycle goes to 60-65%. ICP correspondingly climbs and climbs to 3700 psi.
Is this IPR reading a real or inferred reading? I have read that the PCM will disregard the actual ICP reading and report an inferred value if the actual ICP reading is vastly different from the desired. If this is the case, one could see high ICP on the scan tool while still having low ICP.
I have seen it suggested to monitor voltage at the sensor itself. I back probed the wires and interpret the following:
Black with white stripe = ground
Gray with pink stripe (?) = 5v ref
Blue with green stripe = signal
I get 5v KOEO at the reference wire. I get 4.6v at the signal wire. According to a chart I found, 4.6v is pegged high. There is no change in the signal wire voltage when cranking. Therefore I infer that the sensor is bad, and the PCM is making up values for ICP.
I hope someone can corroborate my understanding so that I can feel confident spending $150 on the new part.
If the sensor is indeed good, if anyone has an explanation of how it works electrically speaking, and any other thoughts on why the injectors are spitting no oil (not firing, I assume), they would be most welcomed.