Bad HPOP?
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Freshman User
Joined: Mar 2022
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Bad HPOP?
I bought this truck about a year and a half ago. First problem I had was injector O-rings, replaced those.
a couple of months later had an issue and with trouble shooting replaced the CPS, IPS, IPR, and finally found a bad injector.
Last winter I didnt have any problems with it but this winter I had started it several times and it would die, I could fire it up and it would lope real hard then smooth out and back to the races we would go
A couple of weeks ago I got a CEL, injector 1 low to high code along with a low injector oil pressure code. Went ahead and changed out valve cover gaskets to see if it was a wiring issue but with no luck. Over the past couple of weeks I have noticed increasingly that about 1600 RPM it looses power and kind of chugs, almost a miss but not a flat out dead miss
I have had an oil leak for a little bit and finally found some time to locate it for sure, it was the factory HP lines to the heads, replaced them yesterday with the CNC fab lines that delete the quick connects from navistar.
Driving back from the shop to the house I noticed above about 45 MPH the truck would run really rough, at the time I assumed air in the high pressure system. Also cruising about 60 if I would throttle down it would become very rough. About 6 miles later I let off the throttle to turn off the highway and the truck just died, couldnt restart and towed it home.
I hooked up my OBD connector and forscan to see any readings, I attempted to restart with the IPS disconnected and nothing. the readings from the forscan while cranking are
RPM 174 (OBD reading, no dash reading)
IPS 46 PSI
IPR 90%
Injector pulse width .6 milliseconds
The truck has plenty of oil in it so my best assumption is my HPOP has failed?
Thanks for any help in advance or any other problems I may be able to chase down
a couple of months later had an issue and with trouble shooting replaced the CPS, IPS, IPR, and finally found a bad injector.
Last winter I didnt have any problems with it but this winter I had started it several times and it would die, I could fire it up and it would lope real hard then smooth out and back to the races we would go
A couple of weeks ago I got a CEL, injector 1 low to high code along with a low injector oil pressure code. Went ahead and changed out valve cover gaskets to see if it was a wiring issue but with no luck. Over the past couple of weeks I have noticed increasingly that about 1600 RPM it looses power and kind of chugs, almost a miss but not a flat out dead miss
I have had an oil leak for a little bit and finally found some time to locate it for sure, it was the factory HP lines to the heads, replaced them yesterday with the CNC fab lines that delete the quick connects from navistar.
Driving back from the shop to the house I noticed above about 45 MPH the truck would run really rough, at the time I assumed air in the high pressure system. Also cruising about 60 if I would throttle down it would become very rough. About 6 miles later I let off the throttle to turn off the highway and the truck just died, couldnt restart and towed it home.
I hooked up my OBD connector and forscan to see any readings, I attempted to restart with the IPS disconnected and nothing. the readings from the forscan while cranking are
RPM 174 (OBD reading, no dash reading)
IPS 46 PSI
IPR 90%
Injector pulse width .6 milliseconds
The truck has plenty of oil in it so my best assumption is my HPOP has failed?
Thanks for any help in advance or any other problems I may be able to chase down
Hotshot
Joined: Mar 2014
Posts: 10,750
Likes: 1,065
From: Douglassville, PA
HPOPs rarely fail but they do. They are also expensive so it would be best to eliminate all other possibilities and the first one I would look at would be the IPR. You say that you replaced that but did you use a genuine OEM? OEM is the rule of thumb here even though they are often much more expensive. Prices can even be obscene but they work and aftermarket doesn't. You could perform a deadhead test on your HPOP if you need to. There is probably a write-up on that in the tech folders up top. Welcome to FTE and quit throwing expensive parts at it, as you have found, it's costly and ineffective. So...OEM IPR? Do you still have your old one?
Got Data?
Joined: Dec 2012
Posts: 4,274
Likes: 1,411
From: Lake Stevens, WA
Did you check or replace the UVC harnesses when you changed the valve cover gaskets? Recommend checking the resistance of the injector solenoids at the 9 pin connectors on each bank for the correct resistance (around 3 ohms). Bank 1 is the passenger side - start there. If good, check at the 42 pin connector. If still good, might need to check at the IDM connector.
Looks like 2 problems, electrical and oil. I'd fix the electrical first and go from there.
From your profile, you have a 2003 with 200K-250K miles - is that still correct?
Looks like 2 problems, electrical and oil. I'd fix the electrical first and go from there.
From your profile, you have a 2003 with 200K-250K miles - is that still correct?
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Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
Sounds like multiple wiring gremlins. IPR valve connector or pigtail is a likely suspect for your low high pressure oil. Once the wiring is squared away might consider a fuel pressure test. Your low power and rough running conditions could be explained by low fuel pressure.
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Thread Starter
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Freshman User
Joined: Mar 2022
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yes 211K
I just put new UVCH in last weekend (its my only ride, if it seems like the solution I dont have time to have it down)
I could check out the pigtail, i'll see if I can dig up a voltage for KOEO
I've got to stop by a hydraulic shop tomorrow and see if they can make me a gauge to put on the pump, I think the CNC fab lines are 5 AN but I'm not positive on that.
Also need to check reservior level, meant to today but life got in the way
have not checked fuel pressure but it flows in the fuel bowl while the key is on, was full when the truck went down
I just put new UVCH in last weekend (its my only ride, if it seems like the solution I dont have time to have it down)
I could check out the pigtail, i'll see if I can dig up a voltage for KOEO
I've got to stop by a hydraulic shop tomorrow and see if they can make me a gauge to put on the pump, I think the CNC fab lines are 5 AN but I'm not positive on that.
Also need to check reservior level, meant to today but life got in the way
have not checked fuel pressure but it flows in the fuel bowl while the key is on, was full when the truck went down
Last edited by bomccorkle; Mar 7, 2022 at 08:35 PM. Reason: more info
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
The pcm controls the the ipr with a modulated ground circuit, so you should see battery voltage on one terminal whenever the key is on. The other is for the pcm to give or take the ground as needed. Don't be fooled into thinking all is well just because the connector and loom look ok. The wires shorting inside the loom is a common issue, you'll want to open the loom a ways for a thorough inspection.
The hpo lines should be a -6 (3/8) JIC/AN
The only real way to be sure about the fuel pressure is a gauge hooked to the fuel bowl and take some idle and WOT readings. There is an easy method in the tech section that uses the fuel drain valve as a temporary test port.
The hpo lines should be a -6 (3/8) JIC/AN
The only real way to be sure about the fuel pressure is a gauge hooked to the fuel bowl and take some idle and WOT readings. There is an easy method in the tech section that uses the fuel drain valve as a temporary test port.
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Freshman User
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I went ahead and hooked a hydraulic gauge to the driver side high pressure line, it reads about what the ICP is 50-100 psi
pulled the IPR pigtail loose, pulled back the loom over to the head and the Y where it meets with the fuel bowl heater, found nothing suspect.
Checked the voltage on both sides KOEO, 13 both ways
when I plugged the IPR back in I still had the key on and I swear I heard it click, but I couldnt get it to do it again, I would suppose that is a 1 way solenoid and the HPOP presses it back home
pulled the IPR pigtail loose, pulled back the loom over to the head and the Y where it meets with the fuel bowl heater, found nothing suspect.
Checked the voltage on both sides KOEO, 13 both ways
when I plugged the IPR back in I still had the key on and I swear I heard it click, but I couldnt get it to do it again, I would suppose that is a 1 way solenoid and the HPOP presses it back home
Lead Driver
Joined: Oct 2005
Posts: 6,129
Likes: 1,919
From: Ponca City, OK
I went ahead and hooked a hydraulic gauge to the driver side high pressure line, it reads about what the ICP is 50-100 psi
pulled the IPR pigtail loose, pulled back the loom over to the head and the Y where it meets with the fuel bowl heater, found nothing suspect.
Checked the voltage on both sides KOEO, 13 both ways
when I plugged the IPR back in I still had the key on and I swear I heard it click, but I couldnt get it to do it again, I would suppose that is a 1 way solenoid and the HPOP presses it back home
pulled the IPR pigtail loose, pulled back the loom over to the head and the Y where it meets with the fuel bowl heater, found nothing suspect.
Checked the voltage on both sides KOEO, 13 both ways
when I plugged the IPR back in I still had the key on and I swear I heard it click, but I couldnt get it to do it again, I would suppose that is a 1 way solenoid and the HPOP presses it back home
When my pigtail shorted out it was at that y in the loom.
Couple other things you can check are the solenoid resistance, should be 10-12 ohms I believe. You can make a jumper for the IPR to the battery to rule wiring out. Then there's deadheading the pump to a gauge.
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Freshman User
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pulled passenger side and got about 60-80 PSI
Did HPOP deadhead got around 100 PSI
Will make 12V power cable to make sure IPR is energized and try that tomorrow, after that will switch to known good that I have on hand
Did HPOP deadhead got around 100 PSI
Will make 12V power cable to make sure IPR is energized and try that tomorrow, after that will switch to known good that I have on hand