Bad ICP?

6speedsd · Sep 3, 2016

I'm usually pretty good at figuring these things out, but I'm coming up empty with this one. 2005, with the works. All updated parts, ******s, ect. Got a hot no start last week. Was only building 300psi ICP. Unplugged ICP, still wouldn't start. Let it sit for about 20 mins, hit the key and it slowly rolled into a start. Drove to work, shut it down, waiting 30secs or so, hit the key and it fired right up. It's screaming bad STC, but I was pretty sure I changed that when I had it apart. Got home and looked through my box of goodies, and there it was....brand new stc kit in unopened bag. Figure great, that's my problem. Tore it down over the past weekend, only to find it already has the updated fitting. Changed it anyways while I had it apart. Ran it a while Sunday, and it wanted to roll into a hot start again. Didn't drive it this week, and had a chance to air test it today. Put 150psi of shop air in it and didn't hear a single leak....both with IPR closed and open. Part of me thinks I have a biased ICP sensor, but I'm not so sure. Readings per AE...

Key on,
ICP 0
ICPv .24
IPR 14.84%

Cranking it builds ICP slooooow, up to about 250-300 then it'll shoot up to 500ish and Fire.
While cranking,
ICPv .3-.4 until it fires, then jumps to 2.42v (but only shows like 650psi), then drops back to .8ish volts.
IPR goes to 84% pretty quick.

Once it's idling, EOT/ect maybe 100-120
ICP 580ish
ICPv .93
IPR 23%

Truck runs perfect. No codes, no misses, nothing.

If I shut it down, shouldn't it hold some pressure in the system? As soon as I shut it off, and cycle the key right back on, it's showing zero ICP, and has to build again before it'll fire.

Part of me still says it's a leak somewhere....then another part says my HPOP is crapping out....then another part says it's a bad ICP. Seems like a bad ICP that was reading low would cause my issue somewhat, but then again it should have fired when I unplugged it.

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webb06 · Sep 4, 2016

Icp numbers make me say ipr valve first but possibly the hpop since it's so slow to build pressure and you didn't hear any leaks.

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6speedsd · Sep 4, 2016

Forgot to mention...
LPOP seems to be good. Filter housing fills pretty quick when cranking, and dash gauge comes up fairly fast as well. I checked the IPR last weekend when I had the pump off. Screen was intact, and as clean as a new one. However it and the ICP, as well as the HPOP, are original to the truck since I bought it with 117,000 miles on it. Has like 195,000 now. No idea if any of them were changed prior to me owning it, or if they are factory originals.

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78f100 · Sep 4, 2016

If your icp sensor is showing 2.4 volts and only 6 50psi it's bad, it may not be your only problem but it's bad.

sootie · Sep 4, 2016

disconnect the icp sensor and see what changes

webb06 · Sep 4, 2016

sootie said:
disconnect the icp sensor and see what changes

He already did that. Still no start

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6speedsd · Sep 4, 2016

It spikes up to 2.4 as soon as it fires, but immediately drops back to .8ish, which matches the 650psi.

.3-.4v while cranking
.2v key on

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78f100 · Sep 4, 2016

Ok, what's the ipc reading with the sensor unplugged koeo and koer. I've seen several shorted in the harness, so unplugging the sensor wouldn't make much difference. The pcm is still getting what it thinks is a pressure reading from the shorted wiring.
If you didn't hear a leak, and ipr is only at 23% running doesn't really sound like you have a leak. And during the leak test did you command the ipr open and closed? You should be able to hear a definite difference, if not the ipr may not be doing its job. Even though the percentage is changing, doesn't mean the regulator is actually moving.

6speedsd · Sep 4, 2016

I was actually expecting to hear a definite "click" when I commanded it open and closed, but if it did, it was very faint. That sort of made me wonder a little about the IPR, but I never went back to it. I've heard both sides of the story with whether it does click or does not when actuated.

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webb06 · Sep 4, 2016

6speedsd said:
I was actually expecting to hear a definite "click" when I commanded it open and closed, but if it did, it was very faint. That sort of made me wonder a little about the IPR, but I never went back to it. I've heard both sides of the story with whether it does click or does not when actuated.

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Definitely should click. At least when we always check them they do, at least if the ipr is ok. You should hear a leak, coming through the ipr valve, if it isn't working. Then when you close it the leak will stop and should be silent.

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6speedsd · Sep 4, 2016

I heard no leak either way. Was silent when open, was silent when closed.

If it wasn't actuating, why it is still showing 84% while cranking, then leveling out in the 20's when running? Shouldn't my percentages be skewed if it was sticking, or not actuating at all?

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webb06 · Sep 4, 2016

6speedsd said:
I heard no leak either way. Was silent when open, was silent when closed.

If it wasn't actuating, why it is still showing 84% while cranking, then leveling out in the 20's when running? Shouldn't my percentages be skewed if it was sticking, or not actuating at all?

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How long did you leave it pressurized? Sometimes it'll take a minute or so to get the oil pushed out of the system so you can hear a leak at the ipr

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6speedsd · Sep 5, 2016

Wasn't a terribly long time. I'm thinking maybe I should try the air test again, just to double check my previous results.

What's the acceptable time to leave the IPR energized? I've heard anything from 15 seconds to 2 minutes. Sorry for all the questions. I've torn 3-4 of these things down and diagnosed all sorts of issues, but of all things that go wrong with these trucks I've never had to chase down a HPO leak. This is actually the first major issue I've had with either 6.0 I've owned. I tore mine down as a PM....didn't actually have blown HG.

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78f100 · Sep 5, 2016

I cant remember how long they say for sure but when I test them it's usually a minute maybe a little longer. I usually have a hose stuck down by the oil rail and the end in my ear to listen, and I normally don't hear the ipr click. If you're listening really close you will almost always hear a slight leak from the hole on back of the pump. It should be a noticeable difference between open and closed.
As far as the percentage changing, that's the pcm saying what the ipr should be at, doesn't mean the ipr is actually there. You can also command the ipr while it's running and watch icp, it should go up as you command the regulator closed.
Also as web06 said leave the air on it for 10min or so, sometimes it takes several min to leak.

6speedsd · Sep 5, 2016

Got it. I'll try to put air to it again later this afternoon and see what happens. Holidays and family stuff don't leave much time for truck stuff.

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6speedsd · Sep 5, 2016

Humor me a minute...

Was looking back over my data. I watched numbers while it was tuned at first. (Ones I listed were stock tuning) KOEO, ICP reads 190-200. No big deal, as I know ICP is fooled to run higher on bigger tunes. What I noticed is when cranking, it doesn't take near as long to build to 500 and fire off, since it's starting at 200ish anyways. IPR still goes to 84% when cranking, but settles at around 32.5% at idle (higher than stock tuning of course, but again I assume because of the tuning). ICPv is 1.21, and floating around 1000psi.(at idle).

Cranking ICPv is .3-.4v, which oddly enough is the same as when on stock tuning.

Building HPO faster tuned just a coincidence, or am I over looking something? Or should I not even consider tuned data period?

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78f100 · Sep 5, 2016

Tuned data vs stock should be very similar at idle and starting. I have never had a tuned truck idle with 1000psi icp, I'm sure a tuner could write a tune that calls for 1k but it's not normal. It should be 6xx.
I rarely return a truck to stock to diag hpo issues.

6speedsd · Sep 5, 2016

This one has done that since I first loaded it. I don't think these tunes are all that popular, but they absolutely run the best on my truck of any I've tried. He specifically told me he fools the system with a higher icp reading to gain the power earlier. I've just always heard to not trust tuned data when diagnosing. I know while tuned I've noticed icp never reads over like 2800 even at wot, which I always though was weird. When asking the tuner about it, he just said "I fool it so I wouldn't worry about what it reads".

Doesn't explain why it builds icp and fires faster tuned though....which surely isn't a major coincidence.

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6speedsd · Sep 5, 2016

Ok, put air back to it. Finally got to where I could hear air leaking...guess I didn't let it run long enough to push oil out of everything the other day. It's not taken apart yet...I have the oil fill cap off, and the CCV vent off and a stethoscope to listen down each valve cover. You can actually hear air without it, very noticeable out the passengers side, not as much out of drivers. Commanded the IPR closed to 90%, (AE only allows percentage choices in 10's) and heard NO change at all. No change in air, no click from the IPR. I reached back there and got my hand on the IPR while I actuated it on and off and didn't feel anything at all....seems like I should feel something if it were moving...then again maybe not? I'm wondering if the IPR is even working.

Forgot to mention, I've been getting a P2285 ICP sensor circuit low code a good bit through all this. Just assumed if was from all the extended cranking trying to build pressure?

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webb06 · Sep 5, 2016

6speedsd said:
Ok, put air back to it. Finally got to where I could hear air leaking...guess I didn't let it run long enough to push oil out of everything the other day. It's not taken apart yet...I have the oil fill cap off, and the CCV vent off and a stethoscope to listen down each valve cover. You can actually hear air without it, very noticeable out the passengers side, not as much out of drivers. Commanded the IPR closed to 90%, (AE only allows percentage choices in 10's) and heard NO change at all. No change in air, no click from the IPR. I reached back there and got my hand on the IPR while I actuated it on and off and didn't feel anything at all....seems like I should feel something if it were moving...then again maybe not? I'm wondering if the IPR is even working.

Forgot to mention, I've been getting a P2285 ICP sensor circuit low code a good bit through all this. Just assumed if was from all the extended cranking trying to build pressure?

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Sounds like the ipr to me. If it's working and closing the sound should go away or at least change tone if there is an actual leak.

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