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Haha no problem at all! I know it’s been a long haul thus far.
I am home and time for the daily journey of demise… I will log start up, drive, death, and attempt to crank but usually immediately after it dies it doesn’t even crank until it cools. I will try disconnecting ICP and starting as well.
I am home and time for the daily journey of demise… I will log start up, drive, death, and attempt to crank but usually immediately after it dies it doesn’t even crank until it cools. I will try disconnecting ICP and starting as well.
Wait what?!? This is critical information that I haven’t noticed until now. ICP, CPS, fuel pressure and all won’t cause a no crank. I thought we were only dealing with a no start.
I apologize, I was typing quickly on my phone. Not usually only sometimes, as a matter of fact I think it happened only twice of the many times it has died recently and I think it is related to the batteries being dead. Though, I could be wrong. So much as happened in the past two or three weeks, it is hard to keep straight.
Anyhow, today, after it died (took a while longer because it is cooler out), I successfully cranked it with no start, then disconnected ICP also with no start. I logged both attempts (can someone please graph it for me/us?) and here is a photograph I took, surely it is full of oil.
This is the stall, followed by the first no-start attempt - ICP still plugged in I assume. It looks like the PCM is asking for ICP as IPR% is climbing, but ICP stays below 500psi. FUELPW stays at 0.6ms, so no fuel flow commanded. There is an RPM signal too, so the CPS is working.
The next 2 start attempts are with the ICP unplugged, I think. Here is the 1st of those attempts. PCM is reporting default value for ICP, and FUELPW moves from 0.6ms to 2.45ms to initiate a start, but no go. Thinking IPR valve is not responding to PCM command when hot.
Your ICP sensor is still working, but on borrowed time. This data is pointing to the IPR coil. We started with the easiest-to-diagnose and cheapest-to-replace part that could cause a stall/no-start hot, but it appears the ICP sensor is still working, so now the IPR valve is suspect. Recommend changing it out with a new one. It's helpful that this is a repeatable issue.
Did you see any new codes after this last stall in FORScan?
TLDR; 1. O-ring on HPOP was replaced by dealer after purchasing since it was pouring oil out of it, 2. truck died in parking lot, added oil and it started up, 3. truck died and wouldn't start with no obvious issues, cranked fine, 4. replaced fuel filter and CPS with aftermarket, started but only until reaching operating temp and fuel cap was leaking, 5. replaced fuel filter and CPS with Ford branded, 6. tried cooling IPR with ice/water when no start condition, wouldn't start.
Sure seems like this possible IPR open coil issue could be replicated by cooling it. Might take alot of ice water or cooling spray to get it cool enough on a hot engine? I don't know - I have not done that procedure before, but others have had success.
@BWST Thank you for the analysis! New finding... I am now unable to start the truck at all. I let it cool for a few hours as I have been the entire week while I went to eat dinner, just went to the truck and now it shakes the entire truck like an earthquake but no start. Based on your analysis it makes sense to me that perhaps it could be the IPR (like we initially thought) and maybe I just didn't/wasn't able to cool it enough for it to start. Only one new code but expected - P1280: ICP sensor circuit low (from when I unplugged it for the disconnected start).
Last edited by BioEng494; Apr 25, 2023 at 10:36 PM.
Reason: Added DTC
I have been doing some research and attempting to understand the relationship between the IPR and ICP. Can you tell me if I have a grasp on the interplay between these various pieces of the injector pressure system and my situation? The IPR is a high frequency modulated valve that should range between like 5 and 50% duty (via recirculating/bypassing oil out of the system) which essentially recommends ICP to increase injection pressure from 500-3k psi.
In my situation, cranking with ICP connected, the ICP is at sub-500 psi at which the IPR should be increasing up to the max of 50% and thereby increasing the ICP to a higher number as a feedback loop but it seems that the IPR is "increasing" but in reality, perhaps it is not actuating and only theoretically increasing.
Then, cranking with ICP disconnected, the ICP is at whatever the default value that the PCM chooses and not deviating which sets the IPR at a default value and being that neither of them are changing to increase pressure, they're both staying steady at these values regardless of starting.
So to change the IPR to a new one, the theory is that the theoretical increase will now be an actual increase causing IPR % to go up and looping into ICP to increase its pressure.
Unless there’s some sampling delay or such, it appears the rpm starts to drop before ICP falls. Could this be as simple as a failing CPS?
Good catch! I'm not sure why the offset occurs there. There should be very little offset from PID to PID in the log data (much faster than what we observe on the FORScan dashboard/gauge view).
Here is today's stall for comparison, and ICP drop appears to line up with the RPM drop. This data is not always as precise as we'd like - our experience with the symptoms is often as important, if not more so, to get to a proper diagnosis.
As I understand it, the IPR% we see is a commanded signal from the PCM. The actual amount the IPR valve closes in order to raise ICP is not directly measured. When we see IPR% climbing, but ICP staying low, as reported by the ICP sensor, it tells us that the IPR valve is not closing (assuming no other reason for low ICP, such as low engine oil level, an injector o-ring leak, or a weak HPOP).
With an unplugged ICP sensor, the PCM consults a table of ICP values for a given MFDES, and sets IPR% to a value for starting. ICP is "theoretical" not actual, but should be close to that value if the IPR valve is working. In your case, the IPR valve is likely not working, so the actual ICP is not high enough.
The new IPR valve with it's new coil should respond to the PCM commanded IPR% signal and restrict the HPOP return passage, allowing it to build Injection Control Pressure (theoretical ICP becomes actual!).
"The voltage is a constant 12 volts to the IPR. The valve is controlled by a variable duty cycle carried on a 440Hz frequency on the ground side through the PCM."
Check out the entire thread for some good info, including Tugly's link.
I think I understand. So the ICP is simply a monitor for the pressure, it doesn't directly do anything. The IPR is the work horse. IPR changes, ICP sees it and reports it. I think next step would be replacing IPR. Hopefully that addresses the no start issue. I see that RockAuto sells Motorcraft IPR. Being it is the branded valve, is this acceptable? It is $60 cheaper than the cheapest I could find elsewhere (as a Motorcraft anyway).
