What would cause low ICP and low IPR duty cycle?

DZL JIM · Aug 5, 2014

Stumped on a truck with low ICP and low IPR duty cycle.
Reading 500 and 8% and drops at idle till it dies.
Doesn't always do it, but has to be warm or hot and you can count on it dying. Will die while driving when you come to a stop, too.
Then at times it'll drive for a while just fine.
Changed computer and didn't change anything.
No chip installed.
Not sure what else to look at.

TARM · Aug 5, 2014

Messed up IPR or possibly ICP. If the both of them were working correctly and it was the HPOP you would not being seeing those readings from my experience. Considering that the ICP is what the PCM is calling for based on the ICP sensor my first thought is of the two the ICP sensor would be the first thing. Have you tried unplugging it and seeing what happens.

DZL JIM · Aug 5, 2014

I'll have to check with my Tech, I know the owner replaced he ICP sensor with one from Ford so I'm not sure we tried unplugging it.

Rideracelivemx7 · Aug 5, 2014

Couldn't the orings on the ipr do just that if they are bad enough? Assuming you guys didn't pull the injectors, a bad oring can do that same thing.

DZL JIM · Aug 5, 2014

Duty cycle would have to climb sky high to try and maintain ICP.
It's doing the opposite.

Justin@DP-Tuner · Aug 5, 2014

This is an odd one. 8% duty cycle at idle is even strange. I would take a look at the wiring harness for the IPR. Any codes?

psduser1 · Aug 5, 2014

Worn pump?

TARM · Aug 5, 2014

Wiring harness for ICP and IPR would be the next place to look if the ICP has been replaced with a OEM ford one. Next would be the IPR itself.

Worn pump is doubtful as if it was the IPR % would have gone up as its independent of the actual pump and reads only off pressure vs commanded.

At this point I am thinking IPR or harness related but to be honest I have never dealt with this exact issue before.

lincolnlocker · Aug 5, 2014

whoaaaa, thats messed up! gonna have to think about that one.....

live life full throttle

TyCorr · Aug 5, 2014

The ipr is stuck....

lincolnlocker · Aug 5, 2014

TyCorr said:
The ipr is stuck....

dc would go up then.

live life full throttle

TARM · Aug 5, 2014

What were the voltage readings for the IPR?

Vader's Fury · Aug 5, 2014

I have a truck with this exact issue that I had at the ford dealer, an independent shop and finally back in my shop over the last 6 months with out being able to get it running right. I just changed out the engine bay wire harness and it seems that the issue has gone away. Been running for 3 days now without any issues.

I have not had time to ohm out the old harness since it was removed, but I did check the entire thing 6 months ago when The issue first started and didn't find anything wrong with it at that time.

TARM · Aug 5, 2014

So at least in your case it proved to be electrical in origin. That sure seems like what it looks like given the symptoms. To me it sounds like the circuit going to or controlling the IPR or the signalling from the ICP. Maybe tracing those circuits themselves but you would think ohm it out/checking resistance/voltage would answer if there were issues.

DZL JIM · Aug 6, 2014

Vader's Fury said:
I have a truck with this exact issue that I had at the ford dealer, an independent shop and finally back in my shop over the last 6 months with out being able to get it running right. I just changed out the engine bay wire harness and it seems that the issue has gone away. Been running for 3 days now without any issues.

I have not had time to ohm out the old harness since it was removed, but I did check the entire thing 6 months ago when The issue first started and didn't find anything wrong with it at that time.

TARM said:
So at least in your case it proved to be electrical in origin. That sure seems like what it looks like given the symptoms. To me it sounds like the circuit going to or controlling the IPR or the signalling from the ICP. Maybe tracing those circuits themselves but you would think ohm it out/checking resistance/voltage would answer if there were issues.

Thanks for the info, that's kind of what we were thinking, the only thing that made any sense.

Vader's Fury · Aug 6, 2014

Well bad news to report. Guess the wire harness didn't fix the issue as the truck died this morning on the way to a job.

I have changed the following on this thing and it is still acting up. All with ford parts unless noted.

Injectors
Icp sensor
Ipr
Idm
Pcm
Hpop (off a running truck)
Valve cover gaskets
Engine wire harness (off another running truck)
Engine bay harness (off another running truck)

Kinda stumped at this point. Hell even Ford couldn't figure it out and they have a VERY good diesel tech.

I don't mean to derail your thread Jim, just wanted to fill you in on what I got going on with my truck.

I am ready to park it out back, throw a road flare through the window, grab a beer and watch the B burn to the ground. :cursing:

lincolnlocker · Aug 6, 2014

Vader's Fury said:
Well bad news to report. Guess the wire harness didn't fix the issue as the truck died this morning on the way to a job.

I have changed the following on this thing and it is still acting up. All with ford parts unless noted.

Injectors
Icp sensor
Ipr
Idm
Pcm
Hpop (off a running truck)
Valve cover gaskets
Engine wire harness (off another running truck)
Engine bay harness (off another running truck)

Kinda stumped at this point. Hell even Ford couldn't figure it out and they have a VERY good diesel tech.

I don't mean to derail your thread Jim, just wanted to fill you in on what I got going on with my truck.

I am ready to park it out back, throw a road flare through the window, grab a beer and watch the B burn to the ground. :cursing:

does it just up and die or does it spit and stumble before it dies?

live life full throttle

PsdPullerJr · Aug 6, 2014

Is the nut in the back of the regulator tight? I'm thinking it would cause icp to climb but just throwing it out there.

emev0l · Aug 6, 2014

Sounds like there's a clog in the oil drain, since Vander replaced the IPR and HPOP what comes after that? Clogging that would work as an IPR lowering the duty cycle.