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I have a 2006 F250 Super Duty with a 6.0L Powerstroke. I recently purchased in and it started running rough then stalled and now it is a crank no start. I took it to a local diesel shop, and they diagnosed it with a bad FICM. They replaced the FICM but did not fix the problem. After more than a week with no progress at the shop I towed it home and have been trying to diagnose it myself. I ran diagnostics using FORscan Windows version. Here are the things I have done:
1. Checked for base oil pressure. It has base oil pressure.
2. Replaced ICP valve and wire connector. I'm not sure this needed to be done but there were bare wires coming in out of the connector plug.
3. Pulled and inspected IPR valve. The screen was intact and looked to be functioning. I flushed it, replaced the screen and O-rings and reinstalled it.
4. Tested the Ohms on the glow plugs from the glow plug control module harness and the glow plug wiring harness. All had .7 ohms except cylinder 8 which had .4 ohms. I'm also getting a P0678 code.
5. Ran an injector buzz test and although the scan tool said it passed, it was more like a click than a buzz and all 8 injectors sounded the same.
6. Using the FORscan tool, I cranked the engine twice for approximately 10 seconds each time and here are the results:
The only thing wrong in the table on the cranks is that the voltage is too low. You may have too low of voltage, or it could be a fuel delivery issue. I suppose it could be bad injectors also.
Are all 3 FICM plugs solidly connected?
Did you scan for codes?
Injector Pulse Width Command when cranking?
What is the fuel tank level?
How fast will the secondary fuel filter fill?
Any air in the fuel as you watch the empty secondary fuel filter housing fill? Be careful with the fuel filter "fill test". A healthy system fills fast and makes a mess real quickly (hint-it is a two person job).
I would charge and load test the batteries as the first "next step".
It was a good catch to see the higher pressures at KOEO, but at a 42% commanded IPR % Duty Cycle, IMO there should be PLENTY of "actual" pressure to start (and clearly it exceeded the software minimum based on PID data). That assumes that the IPR valve is behaving properly. Hard to say for sure that it is at this point.
It helps to understand the situations where unplugging the ICP sensor actually will make a difference. Unplugging a good ICP sensor that has no wiring issues will not help a no-start. It certainly is an easy enough thing to try though, and especially because we just don't quite get enough information from the PCM on whether or not the IPR valve is actually functioning properly! Unplugging the ICP sensor when there is insufficient high pressure oil pressure for a start (leak or bad HPOP) will not enable the engine to start either.
When you do unplug the ICP sensor, you should also inspect the connector for oil soaking (leaking sensor) and for wire chafing.
The thing about the ICP and IPR is that the software (PCM) can account for some errors in the ICP sensor - by design. That said, many times issues happen when there are problems with BOTH the ICP accuracy, AND when the IPR valve is ALSO sticking or "acting up". This is why it really helps to look at ICP sensor voltage at KOEO. It should be around .2v (some small difference in model year sensors). Then we look at cranking ICP sensor voltage AND we also need to look at the IPR commanded Duty Cycle %.
What complicates things is that the IPR % Duty Cycle is a command, not an actual value.
When troubleshooting, we need to be aware that there is both a software minimum to start (500 psi), and a slightly lower "actual value" for adequate pressure for the injectors to actuate properly to enable a start (assuming a healthy fuel injection system and proper compression, etc). Again, for this reason we look for the health of the sensor (watching sensor voltage output) and watch the IPR valve commanded position.
So if the ICP sensor is reading higher than the actual pressure (bad sensor), it can reach the desired ICP sensor voltage output value before it should (ie exceeding the software/PCM minimum before it should) - this can happen with or without a sticking IPR valve. If only the ICP sensor is bad, the PCM is programmed to hopefully "catch it" and to assume a value (a value high enough to enable a start). In some cases the PCM doesn't do this, and this is when unplugging the sensor helps (unplugging it forces the PCM to assume a value).
A sticking IPR valve can cause the actual pressure value to be below the minimum pressure required to start (PCM and mechanical minimums). So this failure will significantly complicate the troubleshooting when you ALSO have a bad sensor. This situation happens when a bad ICP sensor shows good pressure at an IPR commanded duty cycle that the PCM "thinks" is appropriate (but in this described situation, the actual position of the valve is not matching the commanded value). Summary: unplugging a bad ICP sensor most likely isn't going to enable a start when the IPR valve is ALSO stuck too far open (or as stated above, if there is a bad leak or if the HPOP is bad).
To REALLY understand what is going on in the high pressure oil system (as best as we can anyway), you need to monitor the following cranking information:
cranking speed, rpm.
ICP sensor volts (KOEO and cranking).
ICP desired pressure.
ICP pressure.
Commanded IPR % Duty Cycle.
Lastly, like most v-reference sensors (5v), if there is a v-reference short within the ICP sensor that interferes with this system voltage, unplugging it can sometimes enable starting (y-ref sensors: ICP sensor, EBP sensor, EGR valve position, MAP, Baro, etc).
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