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Discussion Starter · #1 ·
Hi all - my 03 F-250 has been hard starting for the past couple of weeks which I'm trying to diagnose - 1st start of the day takes 3 or 4 tries but then starts ok after that. But what is really causing an issue is that my ICP pressure drops when I push the throttle pas about half way - from 1400-1500 at steady speed, maybe 30% IPR to 600 and 85% IPR once I push the pedal down. It's completely repeatable. Reducing throttle back down will cause the ICP to go right back, and I can hear the injectors change tone when they do. Truck has about 115k miles. I have had the truck for a couple of years but its my nice farm truck and I don't drive it a lot. Is this a failure mode of the IPR? Or of the HPOP itself? It seems to me that if the pump was failing it would have a max pressure it could build and it would stay there, not crash out like it does, or it's somehow running out of volume to pump when the ECM is calling for more.
 

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Discussion Starter · #3 ·
Monitor the ICP sensor volts. Maybe it is the sensor that is the problem.
I can do that - like maybe the sensor is telling the ECM that the ICP is higher than it actually is? The only thing is the IPR stays high in that state - if the sensor was telling the ECM a value it seems the IPR duty cycle would drop off
 

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Discussion Starter · #4 ·
I should also say - the truck has very low power now. It will hold highway speeds on the flat but can't climb a hill; like I thought I wasn't going to make one last week with no load - just a long steady incline. It had more power at 1/2 throttle and 1600 ICP.
 

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I can do that - like maybe the sensor is telling the ECM that the ICP is higher than it actually is? The only thing is the IPR stays high in that state - if the sensor was telling the ECM a value it seems the IPR duty cycle would drop off
ICP sensor sends HPO pressure to the PCM. PCM tells the IPR to move (command only...no feedback) to send more HPO to the injectors, IRP closes more to compensate for lack of ICP. If ICP stays low, PCM tells IPR to close more. And so on, and so on...until IPR maxes out at 85% and stays there. So, what's happening is: 1. the PCM is getting incorrect data from the ICP sensor (that's why @bismic told you to monitor ICP voltage), 2. you have an HPO leak somewhere, 3. you have a failing HPOP, or 4. a combo of any of the 3 :D

Pull the codes
Check ICP sensor and pigtail/plug for oil (early models are prone to ICP sensor failures from oil leaking out of the sensor)
Check ICPv KOEO, while running, and when the truck has the issue
Report findings.

-jokester
 
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Discussion Starter · #6 ·
ICP sensor sends HPO pressure to the PCM. PCM tells the IPR to move (command only...no feedback) to send more HPO to the injectors, IRP closes more to compensate for lack of ICP. If ICP stays low, PCM tells IPR to close more. And so on, and so on...until IPR maxes out at 85% and stays there. So, what's happening is: 1. the PCM is getting incorrect data from the ICP sensor (that's why @bismic told you to monitor ICP voltage), 2. you have an HPO leak somewhere, or 3. you have a failing HPOP.

-jokester
I get it - but why doesn't the pressure stay at it's highest value? If the IPR is at 85% the ICP should at least stay at its highest level, not drop back to basically idle values with a corresponding drop in power. Based on what I've been reading it seems like it's probably the HPOP but this failure mode is a little different than what I've found.
 

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I added a bit more above to my original post. Check those things and let us know what you find.

-jokester
 

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I get it - but why doesn't the pressure stay at it's highest value? If the IPR is at 85% the ICP should at least stay at its highest level, not drop back to basically idle values with a corresponding drop in power. Based on what I've been reading it seems like it's probably the HPOP but this failure mode is a little different than what I've found.
It depends...is the IPR actually moving (remember...no feedback on that loop, only a command).

-jokester
 

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Discussion Starter · #9 ·
ICP sensor sends HPO pressure to the PCM. PCM tells the IPR to move (command only...no feedback) to send more HPO to the injectors, IRP closes more to compensate for lack of ICP. If ICP stays low, PCM tells IPR to close more. And so on, and so on...until IPR maxes out at 85% and stays there. So, what's happening is: 1. the PCM is getting incorrect data from the ICP sensor (that's why @bismic told you to monitor ICP voltage), 2. you have an HPO leak somewhere, 3. you have a failing HPOP, or 4. a combo of any of the 3 :D

Pull the codes
Check ICP sensor and pigtail/plug for oil (early models are prone to ICP sensor failures from oil leaking out of the sensor)
Check ICPv KOEO, while running, and when the truck has the issue
Report findings.

-jokester
No codes

ICP sensor below - looks clean.

Cold start engine - 48 hours since last start, takes two tries. 1st starts and dies, 2nd starts after cranking longer and almost dies. Usually it takes 3 tries

When I left the driveway on cold oil it felt snappy and I saw 2865 ICP with ICV above 2.2 volts but the problem occurred, just later in the throttle position. Once the oil was above 140 it was fully problematic.

ICPv
  • KOEO: 0.15v
  • idle: 1.13v (cold)
  • idle: 0.96v (hot)
  • level steady speed:1.52v
  • when occurring: 1.03v (up hill, throttle down, low power)


  • 776532
 

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Discussion Starter · #11 ·
I added a bit more above to my original post. Check those things and let us know what you find.

-jokester
No codes

ICP sensor below - looks clean.

Cold start engine - 48 hours since last start, takes two tries. 1st starts and dies, 2nd starts after cranking longer and almost dies. Usually it takes 3 tries

When I left the driveway on cold oil it felt snappy and I saw 2865 ICP with ICV above 2.2 volts but the problem occurred, just later in the throttle position. Once the oil was above 140 it was fully problematic.

ICPv

KOEO: 0.15v
idle: 1.13v (cold)
idle: 0.96v (hot)
level steady speed:1.52v
when occurring: 1.03v (up hill, throttle down, low power)
 

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Discussion Starter · #12 ·
Listen - indications are that your ICP sensor MIGHT NOT be working. To verify whether or not it is, post ICP sensor volts along with the ICP psi. If the PCM sees something it doesn't like with the sensor, it ignores it and then makes an estimate of what it thinks it is. The voltage is the ONLY way to confirm what is going on.

Until then, the ICP psi values mean NOTHING.

Also, it is like @jokester00 posted - the IPR % duty cycle is a commanded value. It does not mean that the valve is actually in that position. All 85% means is that the PCM doesn't think the ICP is where it wants it to be.

If you want to just replace an HPOP, then have at it, but you don't know for sure what is going on yet.
I really don't want to replace the pump - I have this truck and two tractors right now giving me fluid pressure issues and I'm not replacing a pump only to have it not fix anything. Learned that lesson a long time ago.

It's interesting you say that about the sensor - after I took the readings above I pulled the plug on the ICP sensor and took it around the block. It behaves exactly the same way as when it's connected.
 

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Discussion Starter · #14 ·
Here are a few values I took while driving around, sensor plugged in

ICPv 1.52. ICP 1161
ICPv 1.00. ICP 728
ICPv .98. ICP 734
ICPv 2.17 ICP 2422 - this is when the oil was cold
 

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Discussion Starter · #15 ·
2865 psi and the voltage should have been at 3.5 - 3.6.

up hill, throttle down, low power ---- 1.03 volts is equal to about 650 psi.

Running with it unplugged is a good test also, but the voltage is the way to nail it down. Thank you for posting those values.
That's about where it was on the scanguage - 703psi
 

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Discussion Starter · #17 ·
Those values look ok on the low end, but to me it looks like the PCM takes over with inferred numbers on the high end.

I would pull the IPR next and inspect it - looking first at the screen on the inlet and then going from there.
Will do I'll try to get it in the morning when its cold
 

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Wish you would have mentioned the downhill/uphill impact in this thread like you did the other (on PSN).

I still think there are issues with the ICP sensor, but starting when facing uphill, but not downhill does point to the HPOP.

Took me a bit to connect your threads on the two forums since they contained different information.

Not the best way to get help - posting partial information in both threads.

Anyway, I'd still check the LPOP performance, then and pull the IPR, then pull the HPOP. Do things in a methodical approach.

Best of luck ......
 

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Discussion Starter · #19 ·
Wish you would have mentioned the downhill/uphill impact in this thread like you did the other (on PSN).

I still think there are issues with the ICP sensor, but starting when facing uphill, but not downhill does point to the HPOP.

Took me a bit to connect your threads on the two forums since they contained different information.

Not the best way to get help - posting partial information in both threads.

Anyway, I'd still check the LPOP performance, then and pull the IPR, then pull the HPOP. Do things in a methodical approach.

Best of luck ......
I'm new to the Powerstroke world and tried to include information about everything in both places, but really wanted to focus here on the ICP pressure while driving as a separate issue. And, not knowing the forums, wasn't sure where the best place to post was. I've found when when asking for and providing help that multiple issues in a thread can cause distraction so I thought the starting uphill/downhill issue could go in one, and the ICP pressure in this one would provide more focus for each. I hope that isn't disrespectful to the forums.

I think I have two separate issues - the staring problem began about 2 months ago, but the power/low ICP started (that I noticed) just this weekend after I drove to the nationals. And I really am trying to understand how the system works.

Thinking about this last night, it seems that the ICP shown on the scanguage is not the actual pressure from the sensor as it behaves the same regardless of whether it's plugged in or not. That certainly changes my diagnostic procedure. Thinking about this last night - if I had a bad ICP sensor maybe the ECM is just running in some kind of safe mode, limiting the pressure to preset levels? I would think I'd see a code for that, but I also unplugged my EGR valve when I got the truck after reading about the problems that can cause and got no light - and no codes.
 

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You need to be looking at the voltage reading from the sensors, the PCM will use internal numbers if the signal from the sensor is unreliable or out of parameter -- the voltage reading will always be accurate

Yours is an Axial Piston pump, it uses a rotating valve plate, that is subject to scoring -- when this happens the plates can separate under higher pressure, and come back together when the pressure lowers. I think this may what you are describing.

The other problem with tilting the truck making a difference in starting, may have todo with the HPOP leaking oil from the reservoir (worn pump shaft or seals) this leak will drain the reservoir over a few hours. The low pressure pump will refill it, but takes some cranking.

ScanGauge is an OK monitor, but falls short on reading codes -- look at ForScan, I have posted several times about it being the goto tool for these trucks
 
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