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HEUI Troubleshooting - Injection Pressure Desired and Actual Mismatch

ckouba

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Anyone have any experience with this?

I have a 2000 M1088A1. The CEL light came on the other day and with CAT ET hooked up, it showed code 164-11 and/or 164-2. Looking them up reveals a somewhat generic trigger of mismatch between desired and actual injection activation pressure on the HEUI system. Scrubbing the internet, it appears that the HEUI pressure sensor or the pressure control valve could be the cause (and are the easiest/cheapest) place to start. To that end, I did replace the pressure sensor without resolving it, and I have a valve I will be picking up after I finish typing this up to see what it might do for me.

The symptoms are weird- the pump can't hit the LOW end of the pressures requested, and is rock steady on the high end. The lowest it would go on the CAT ET diagnostic check was ~1000 psi when 870 is called for. Stepping through the other pressures, it was right on where it should be and steady around that pressure.

When I ran it with the laptop hooked up, it was high when idling, but once any throttle is applied, it seems that called pressure goes right past the actual min and everything is happy. The only time it doesn't match up is when it's idling.

I did run it on a trip, and it ran fine, until it didn't. After a couple miles climbing through sand, it went into limp mode with CEL. Upon extricating myself from the backcountry, the results on CAT ET were worse- still wouldn't hit the low pressures but min was now ~2000-ish pounds (forget specifically at this point). After a bit of consultation, I did an oil change to 30w to see what that'd do because the locals were having a bit of an issue trying to obtain a control valve.

After the oil change, the pressures were all back in line with the exception of the min, again not dipping down below 1000 psi or so. I drove it around a bit and under normal driving conditions, things continued to line up except at idle, so I drove it home (UT to OR, ~1200 miles).

That's where/how it sits today. I will be picking up the new IAPCV (CAT p/n 122-5053) shortly and seeing if that does the trick. Anyone else have any experience with these symptoms?
 

Ronmar

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I played with this on a Ford power-stroke. Same basic components. it has a sensor that reads HEUI pressure and a pressure regulating solenoid valve PRV, that the ECU modulates to vent/regulate hydraulic pressure to maintain pressure according to program. An issue with the earlier powerstroke was a failure in the pump would introduce shavings that clogged that needle valve and ultimately damaged the injectors. They also buried the HEUI pump down in the valley so replacing it was a major evolution…

i hope yours is only a failing PRV, but that is what it sounds like if you have already changed the sensor…
 

ckouba

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Well, it's one of those times where the troubleshooting process makes sense- the pressure wasn't being properly controlled, so I replaced the valve which controls it and BINGO- all back in spec!!!!


This is the CAT ET diagnostic test for the injection actuation pressure control valve. It steps through different levels of desired pressures and the actual supplied pressure should match it (+/- a few psi). Looking at it with the filter of my extensive CAT experience (ie, Youtube University), it looks like it's supposed to!

Will keep an eye on it going forward but pretty sure this issue is resolved!
 

ckouba

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I played with this on a Ford power-stroke. Same basic components.

Funny you mention this... They are the identical parts. Found this out from the CAT guy I chatted with in UT. Same unit as in the DT466 Navistar motor.
 

ckouba

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This doesn't want to go down without a fight.

I started the rig again yesterday morning and it sounded and ran like someone dumped a box of rocks in the crankcase- like it did with the "bad" IAPCV. I didn't have time to monkey with it so I put it on the list of things to do today.

I started it again this morning with the computer hooked up and it started just fine and ran perfectly... for about 4 minutes. Everything matched up perfectly like the initial video.

Then it didn't.

It ran like this when just observing it (note fluctuating mismatch between desired and measured):


Then I ran through the test again and got consistent, crap results:

https://www.youtube.com/watch?v=teAtChRNI$OY

This was with the motor immediately starting cold at around 40°F, running perfectly smoothly for 3-4 minutes, then HEUI pressures running all over the place as shown. Coolant temp wasn't much over 100° when I shut it down. Fuel is fresh, oil is fresh (~1000 miles, 10w-30) as are fuel and oil filters. 12k miles on the chassis.

When I chatted with the OTR truck service place in UT, they said next steps would likely be HEUI pump replacement and then injectors. He didn't think it'd be an injector issue based on how it ran as well as how well it started even if it was hot.

Not wanting to throw parts at it. Anyone seen this before? Anyone got any suggestions?
 

GeneralDisorder

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Well damn.

Adept Ape mentions them jumping around like that and says that means the HEUI pump is going.

You could send out an oil analysis sample and try to read those tea leaves.

I wouldn't screw around at this point. I would get a HEUI pump and injector kit from CAT. As much as that absolutely is going to suck..... it seems likely that you have ruled out pretty much every other possibility.
 

Ronmar

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Did you find any debris in the valve you replaced? That would be a dead giveaway that the heui pump was shot. I recall they specced a modification and installed an oil filter into the HEUI equation. I can’t recall if it was in the supply to the pump or in between pump and injectors to protect them from a pump failure…

like most troubleshooting, garbage in = garbage out. I could think of couple things that could cause this.
1. The pressure is unstable because the source is unstable(bad pump)
2. The pressure is unstable because the valve cannot control it(bad valve or wiring between ECU and valve).
3. The pressure is unstable because there is something going on in the plumbing causing instability and the data shows a system attempting to control the output.

So, 1. Definite maybe… 2. You changed the valve, basically same symptoms, I would carefully go over the wiring, same with the sensor wiring… 3. Have you examined the rest of the HEUI high pressure plumbing? A split line or cracked fitting could be releasing pressure unpredictably and the system is unable to cope…
 

GeneralDisorder

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As to the filter - it's a filter for the HEUI pump oil *supply* and the official CAT setup is only for the C7. They did not create one that I'm aware of for the 3126. There is an aftermarket supplier that makes a filter that goes between the pump and the injectors which prevents a HEUI pump failure from damaging the injectors but does nothing to keep the pump itself from being damaged:

 

Ronmar

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As to the filter - it's a filter for the HEUI pump oil *supply* and the official CAT setup is only for the C7. They did not create one that I'm aware of for the 3126. There is an aftermarket supplier that makes a filter that goes between the pump and the injectors which prevents a HEUI pump failure from damaging the injectors but does nothing to keep the pump itself from being damaged:

I was thinking they did that supply filter as a retrofit kit to the 3126, and i recall now the aftermarket High pressure filter kit. The spool valves on the injectors most definitely need clean oil…
 

GeneralDisorder

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I was thinking they did that supply filter as a retrofit kit to the 3126, and i recall now the aftermarket High pressure filter kit. The spool valves on the injectors most definitely need clean oil…
The supply filter comes with the HEUI pump and injector kit for the C7. Indeed I had to scour the Internet just to find the part numbers to install the filter kit on my C7 because CAT doesn't sell a "kit" for just the filter if you want to install it preventatively - probably because Installation requires compressor removal. I had my compressor off anyway and the filter parts are $200 so it was an obvious upgrade and the original supply hose didn't look that great. The filter parts include a shorter hose, etc.
 

ckouba

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Did you find any debris in the valve you replaced? That would be a dead giveaway that the heui pump was shot. I recall they specced a modification and installed an oil filter into the HEUI equation. I can’t recall if it was in the supply to the pump or in between pump and injectors to protect them from a pump failure…

like most troubleshooting, garbage in = garbage out. I could think of couple things that could cause this.
1. The pressure is unstable because the source is unstable(bad pump)
2. The pressure is unstable because the valve cannot control it(bad valve or wiring between ECU and valve).
3. The pressure is unstable because there is something going on in the plumbing causing instability and the data shows a system attempting to control the output.

So, 1. Definite maybe… 2. You changed the valve, basically same symptoms, I would carefully go over the wiring, same with the sensor wiring… 3. Have you examined the rest of the HEUI high pressure plumbing? A split line or cracked fitting could be releasing pressure unpredictably and the system is unable to cope…

1 - Are you asking bad low pressure (block) pump or bad HEUI pump? I can confirm that my block oil pump was consistently giving me good pressure at the dash gauge- 60's at start up, high 30's or low 40's underway when warm. I assume you're talking about the HEUI pump though, so yeah, definite maybe. The only thing which makes me think the pump might be OK is that it does its job flawlessly from time to time. Of course, it might just take that little bit of time to have whatever the issue is manifest itself and need to be changed, so it may just be a hopeless distraction.

2 - The wiring is definitely on my list of things to check. I will trace back the harness and look for suspect connectors, etc... I have already seen that on the chassis harness.

3 - Nothing looked bad on the hardware and plumbing. I had the valve cover off when we were still in UT as well and nothing looked out of place in there- at least with the motor off and cool.

I saw nothing in the valve all three times I removed it- first to replace it originally, second to remove the one which made it run worse and re-install the first, then upon our return from UT when I replaced it again and made that first video. Nothing in the ports, nothing anywhere to make me suspicious of something in the system.

The initial valve I removed had a compromised part of its body where the electromagnet installs. The casing was crimped, enough so the actuator wouldn't spin freely on it. I was hopeful that something was binding or otherwise being affected internally by this and that swapping to a new, uncrimped control valve would resolve the issue. It did initially, but not permanently. The two replacement units had no such issue- the actuator spun freely on the valve body as intended.

I saw the HEUI filter kit update for the C7 and the video about the IFS one. Leaning toward putting this all together as I wasn't excited when my CEL went on and I was in the absolutely most inconvenient location to get assistance. Would like to be a bulletproof as possible.
 

GeneralDisorder

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We can put an oscilloscope on the control wires to the IACV and compare to the percentage listed in CAT ET and see if the signal is stable or dropping out, etc. That would be very straightforward with my PICO Scope. Same for the pressure sensor. Conceptually it's possible for the ECM driver to be having some conniption when it gets hot or for there to be a bad connection. Although given the behavior and what we know from YouTube university my money is on a mechanical problem with the HEUI pump.

I'm not sure about the C7 HEUI supply filter fitting the 3126. I think I looked at that and the connection at the block was totally different. On the C7 it's a flange with two bolts and IIRC the 3126 is perhaps an ORB fitting to the block. Which would mean the official CAT supply line wouldn't work. The filter itself and the fitting at the pump would work, but a custom line would be needed for the block side I think. I could be totally wrong though I didn't look that close and it's been a while. Possible I'm sure though.

If it's the pump, this would be my list:

1. HEUI pump and injector kit from CAT.
2. HEUI oil supply filter parts and possibly custom line from filter to engine block.
3. IFS injector filter kit.
4. Engine oil pump.
5. Inspect rod and main bearings and potentially replace.
6. Carefully inspect turbocharger for shaft play.
7. Potentially investigate oil cooler for warping and damaged internal gasket - this can cause oil to bypass the main filter:

 
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GeneralDisorder

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I would take the valve cover off and run it so you can see how the HEUI lines are performing under pressure…
Don't believe there are any lines except the single line from the pump to the head. All the injectors are fed oil through drilled passages in the cylinder head I'm pretty sure. I didn't notice any lines when I changed my injector wiring harness anyway......

Cat-C7-Long-Block-Engine_HEUIOilrailplugs_(full).jpg
 

Ronmar

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the earlier HEUI had separate lines, and they were a weak link. Anything long the path though that is exposed to the oil, like all the injectors and their seals could also cause issue… just exploring possibilities that would effect HEUI pressure…

I wonder what his pressure looks like if he unplugs the actuator electrical connection…
 

ckouba

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I wonder what his pressure looks like if he unplugs the actuator electrical connection…

I can try to answer that question later in the week. Will take a poke through that video, in the meantime, starting to make a parts list.
 

ckouba

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Don't believe there are any lines except the single line from the pump to the head. All the injectors are fed oil through drilled passages in the cylinder head...
Can confirm. Nothing to really see from a plumbing perspective with the valve cover removed. I was checking connectors and wiring when I was in there.
 
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