If you really have 0 psi at the ICP, then I don't think a stuck poppet is your issue. You need to check oil pressure, volume, or the IPR. The duty cycle read by the scanner is only what the PCM is calling for, not what actually is going on. A few things you can try.

Apply 12 volts to the IPR and see if that makes it start. Remove the plug from the top of the HPOP reservior (if you don't mind making a mess) and see how much oil flow you get coming out of the hole. (will seem like a lot and checks LPOP). Remove the ICP and crank (put rags over the hole. if everything is working, this will result in holy sh** that's all the oil in the engine spewing out)

 

Can you elaborate some on applying the 12V to the IPR?

I kind of don't want to make a mess like that and get oil all over the engine and ground. Is there a less messy way to get the same information? Can a bad IPR cause zero pressure?

The HPOP reservoir is full to within 1/2" of the top. I don't have a LPOP gauge.

 

You can pick up a LPOP test gauge at HF for about 30 bucks. I think Stewie means doing 12v while it's in the truck. I could be mistaken though.

 

I got the USB adapter finally (UPS misdelivered it - when I called them, the driver helpfully explained that she had left the package at a white house - am I supposed to knock on the door of every white house in the neighborhood looking for my package?) and wow can it read codes. Like someone else said, Forscan reads EVERYTHING.

First, I tried to run a buzz test. It sat there for 20 seconds, I heard some relays clicking under the hood, and then it threw a DTC at me - P1668. This is the code for "unable to communicate with IDM".

The rest of the codes:
P1280 - ICP circuit out of range low. Is this because there is no oil pressure during cranking? Or a bad ICP sensor? There is no smoke at the tailpipe
P0472 - EBP sensor low input. I don't know why I'm getting this one. Just changed the EBP sensor and it reads 14.6 PSI KOEO.
P1000 - because the batteries have been disconnected
P1670 - EF signal not detected - no idea what this one means
P0603 - battery disconnect
P0676 - glow plug #6 short. Will probably have to pull the valve cover to fix this
P0683 - GPCM comm fault. Probably need to replace the GPCM.

Can I test the IDM? Or am I better off sending it to Chattanooga?

If the IDM is the problem, why am I getting no oil pressure? Surely these two things aren't related?

 

Sorry if missed it, but did you ever physically check ipr? I had tin but come off and solenoid slide back , looking at obd values showed very similar ipr rising icp stationary. Took step back ( calmed down ) started with simple things first. 2 min later back on road.

 

I checked it to make sure the tin nut was tight. I haven't done much else with it but I'm going to unplug it later this afternoon and see if it will start without it. I would love to put 12V on it and test it that way but I don't have a spare harness for it.

If I'm really getting zero ICP I'm starting to think the bolt sheared or backed off but it seems weird it would do that 20,000 miles after I put it all back together last March.

 

I went out and ran a few tests to eliminate some potential causes.

- Unplugged fuel bowl heater. No change.
- Unplugged IPR. No change BUT I'm not that this is even a valid test.
- Tested (with an ohm meter and power source) the PCM and IDM relays. Also checked the IDM fuse under the hood. Everything checked out.
- Removed the front cover and checked the torque on the HPOP shaft bolt. I tried to back it off and the engine spun. I torqued it back on until it spun the other way then gave it a couple hard shoves with my 1/2" ratchet. The bolt didn't move through any of this, so I can eliminate a broken bolt or shaft.

I think I'm going to bite the bullet and order an IPR, ICP, and CPS (the last because I have my wallet open) from Riffraff and call it a day. I hate throwing parts at the problem but I think I've narrowed it down far enough and I'm sure that those parts are all original (except for the ICP).

 

Did you just check, or completely replace fuse 30?? With the fuel bowl heater unplugged?

My truck did this and I used my dvom to check continuity on all fuses and it ended up being the fuse. No idea..........

Denny

 

It won't be called an IPR pigtail, but many of the auto parts stores sell a plug that will work for the IPR. You can also use test leads with small alligator clips.

But if you're not getting any communication communication between the IDM and PCM, then there's nothing calling for any high pressure oil. If you're just getting regular low pressure oil through there, the ICP sensor may not pick that up. I don't think it starts till 100 psi, but I could be wrong on that.

There are no relays that click under the hood with a buzz test, but you do hear the buzzing or clicking of the injectors. All 8 buzz at once in the beginning, then each injector buzzes individually, so 9 total separate sounds. If that's what you heard, then the IDM and PCM are communicating.

 

I had no problem removing the hpop bolt however, when installing, it mafe to 69ish# b4 turning motor. Had to use cheater bar on a breaker to wedge it on the concrete to finish torqing to 95#

 

I didn't check the fuse with the meter but because it's a maxi fuse you can see all of the copper inside the fuse. I didn't have a spare of that type. When you say that your truck did this, can you be more specific? Did you have zero ICP and a blown IDM fuse?

An FTE member has offered to send me a couple of leads. Yeah I could do it with alligator clips but I don't have those either. I don't really want to spend a bunch of time explaining to parts store people what I'm doing - it would take forever where I live.

The IPR duty cycle peaks at about 65%, so I think that the PCM is in fact calling for high pressure oil. In a youtube video I watched yesterday, a tech was working on a 7.3L that was showing around 40 psi. So the sensor does seem to read that low.

I heard relays clicking from the fuse box under the hood and no buzzing from any of the injectors. I don't know what else to tell you.


So here's where my thought process is with the potential IDM issue. I do know for a fact that no oil pressure, or at least the signal for no oil pressure, is causing the no-start. That has to be fixed above all else. I've never run a buzz test before, so for all I know it never worked on my truck for whatever reason. It's possible that once the oil pressure situation is fixed, the truck will fire right up and still refuse to run a buzz test. So I'm going to focus on fixing the oil pressure problem first.

 

So, by Andy isolating the IPR and connecting the IPR pigtail up to a 12v source he should be able to start the truck as normal? If the truck does start, then we know he has a bad IPR?

Is that how this test procedure is performed?

I will be sending Andy a couple of connectors off the harness I took off last week. He should be able to perform the test soon, but was trying to nail down the procedure for others to read later and so that I could have an idea of how this works.

 

I didn't think you could start the truck with the IPR unplugged, jumped or not. This should be interesting. He never told me if the connector was tested or looked at or not. I told him it is very possible the connector is bad in the pigtail where you can't really see it, but I have no idea.

 

Maybe its mechanical. Could be a blown lpop that destroyed the front cover..

 

This video:
Pretty much explains it all. By supplying 12V to the IPR, it cuts the PCM out of the picture. If I still have no pressure, then the IPR could still be bad. The IPR uses the same style connector that injector solenoids do.