Ok......
The relationship between the injection pressure regulator and the actual/desired injection control pressure goes a lil' sumpin' like 'dis.
1. The PCM bases an initial injection pressure regulator duty cycle using the IPR map to attain a desired injection control pressure.
2. The PCM looks at the actual injection control pressure data from the ICP sensor.
3. The PCM makes fine adjustments in the IPR duty cycle to get the desired injection control pressure reading from the ICP sensor.
Every varying load/RPM will start with an initial duty cycle commanded by the PCM and constantly tailored adjustments by looking at ICP sensor output.
This entire system is called a "feedback loop". It's very similar in operation to how the oxygen sensors relay to the PCM about how accurate the air/fuel correction is.
When the base IPR duty cycle is off, then the initial duty cycle for a desired injection pressure is off and if it's off too far in a certain operating range, then the PCM cannot correct it and maintain a stable RPM because the actual pressure desired varies too much from the desired and the PCM basically fights itself because the map is no longer valid. I recognize that as a run-on sentence but I'll leave it that way because that's how it came out of my head.
I know what I want to say but I don't think it came out right.
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Tuning, flashing, burning chips, and repairing all aspects of 7.3L Powerstrokes.
SEVEN 7.3L-powered vehicles in the driveway. Two didn't come that way from the factory!
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