Hey everyone. I’m new here. Long time viewer first time posting.
I’m having hell with my 1999 7.3.
had a pretty bad loss of power for awhile now and can’t seem to figure it out. I’ve recently replaced oil cooler “leaking”. Fuel bowl drain valve. “Leaking”. O ring on Hpop plug “leaking”. New Icp. New ipr. Rebuilt turbo. Anyways I’m getting really high ipr at wot. 64.84. And Icp struggles to reach 11-1200 wot. I have a spare Icp and same issue when I swap it. The weird thing about it is if I unplug Icp the truck dies instantly. And will not restart. If I kill truck the. Unplug Icp it will not start. I’m at a loss here bc I know it should run/start with Icp unplugged but it just won’t. Is it possible I just need a new pigtail on it? I’ve thrown so much money at this truck trying to find the issue and I just can’t seem to find it. I had a “mechanic” do injector cups for me about a year ago and ended up costing me 10k bc of all the issues he created. Any help would be greatly appreciated!

 

Howdy and welcome. Sorry it’s under such circumstances.

First of all, ouch on the “mechanic” thing. Yikes!

I think the bold items are key, which you already spotted and is why you were sharing.

The truck should run with ICP disconnected. The IPR will be commanded off of standard tables instead of actual values. Which means I think your actual ICP pressure is much lower than standard.

It could be a bad IPR. I know you changed it, but does it act exactly the same with both? Was it a genuine motorcraft from a reputable supplier? (Amazon and eBay stores are not trusted) Same goes with the ICP but I don’t think that’s your issue right now.

Maybe the IPR wiring. Pull back the loom (way back) and look it over well. Others here can help you measure continuity from the 42 pin to the IPR pigtail.

It could be an actual pressure loss. The “mechanic” put the injectors in. An oring could be bad bleeding off your ICP. Any oil in your fuel?

I’d start with these items and go from there.

 

yes Icp and ipr and genuine motor craft. I don’t think there’s oil in fuel. I loose a quart every 5000 miles or so. But I’m around 280k on this truck now. I pulled back Icp wiring and it all looks good but I only pulled it back a foot or so. Maybe I should inspect ipr wiring in the morning. I’m kinda stuck in flagstaff Az for awhile working living in hotel so my sources are kind of limited. I do have FORScan that’s how I can read Icp and ipr live. I’m leaning towards Icp wiring/plug for whatever reason but I’ve thrown so many parts/money at this thing I’m just beat. If there’s a good way to check Icp wiring for continuity that would be a great start! I’m not new to wrenchin on things. Just really want to throw in the towel and hoping someone has experienced this same issue that could share! Thanks guys!

 

There are some wiring diagrams in the tech folder.

I do not think it’s ICP related due to it dying when disconnected. This points me in the direction of IPR.

 

Ok I will look at that. Is it possible that the ipr is like sticking open/closed? I don’t see any leaks on it but maybe it’s sticking somehow? My thought is the wiring is ok because I can live up live readings. It idles around 11 but as soon as I really get into it the truck will hardly accelerate and my ipr goes to 64.84. Sorry for the scattered posts I’m afraid I’m just throwing parts at it for no reason

 

No, IPR live readings do not mean the wiring is ok. The IPR value in the data stream is the commanded %. It’s simply what the PCM is telling the IPR to do.

The IPR is a valve controlled by the PCM to adjust the ICP. Yes it’s possible for it to be sticking or not responding correctly. They sell rebuild kits for them. But I’d do some more investigation before buying parts.

ICP is showing a returned value from a sensor. Wiring issues here can cause low/high readings. But in your case it appears the low ICP is real due to it running poorly and not running when disconnected. If it were showing high and died when disconnected then I would consider the ICP wiring as a possibility.

 

Further to what Jason said, sounds like the ICP is working. It senses HPO, tells the PCM, and if the PCM wants more power it increases IPR duty cycle. Max is 65% and yours is doing that according to Forscan. But the IPR is not building the commanded pressure. Or the pressure is bleeding off downstream of the IPR.

Make sure the tinnerman nut is still on the back of the IPR.

Otherwise I'm drawing a blank atm, sorry to say.

 

Thanks for all the responses. I checked ipr wiring visually and all looks good. I also changed the outer pieces of ipr with another one I had in the toolbox. Still nothing.. it always starts and has really long/hard starts when up to temp. Would bad o rings on ipr cause loss of power and hard warm starts? And the Icp/ipr pressure issues? I’m just guessing because I feel defeated with this. I don’t remember changing ipr before. I know I did I can’t remember if I need to do anything special or just pull it and put new one in? Is it going to dump Hpop reservoir every where? Fuel?

 

Pulling IPR will allow for oil to drain in valley, a bit of a mess, but not a huge ordeal.
At this point, It may be the IPR, or it could be the hpop, or it could be a leak downstream. One of the best ways to diag furthur, without incuring significant costs, would be to deadhead the pump. Cap one line coming off the hpop and put a 5,000psi gauge on the other, cranking via key the pcm will read zero psi due to no hpo going to the heads and therefore the icp not seeing icp, this should cause the ipr to be commanded to close and build max pressure. You can also apply voltage to the ipr manually for short durations while cranking. The gauge should register about 3,500psi within a couple seconds of cranking. If not then you either have a faulty ipr or a faulty hpop, or both.(this is where an ipr blockoff tool is handy as it eliminates the ipr and does a true deadhead of the pump).

If you do build pressure quickly, then you know you either have a leak downstream, or a lpop supply issue under volume demand. To check downstream leaks you would do the deadhead test, but this time hook up one head at a time.(note: manually applied voltage to ipr works well for drivers side as the icp sensor, unless removed will see pressure and pcm may not command ipr to fully close)

You can check lpop pressure at the port on top of the reservoir (-4orb fitting) by putting a 0-100 psi gauge on it while cranking and/or running at idle and/or under load or elevated rpms.(lets focus on hpop deadheading first)
https://www.ford-trucks.com/forums/1...l#post20397196

 

Do the air test to each head one at a time. If no leaks I would say HPOP is bad. There are some good shops there in AZ. If you can't find it, go to one of them! KC is closest to you, might want to give them a call and ask who they would go to.

 

Ok thanks for the quick reply. KC is the shop? Or Kansas City?

 

It’s just so weird I’ve been fighting this for awhile. Truck starts good. Runs pretty good. Just has no nuts at all! When going uphill im pushing 50-55 with my foot on the floor and nothing! And it doesn’t like to start if I shut it off and turn it right back on warm. If I idle for a couple minutes when I park then shut truck off it always starts back up easy. I’m going to look into it more this afternoon

 

Where did you purchase the motorcraft IPR? Many many convincing fakes out there.

 

KC Turbos
https://kcturbos.com/

@Peixinho (Charlie) and the crew at KC are good peoples

 

KC is a great resource are we are local here in Az. We can try walking you threw diag over the phone. 480-688-7160
kcturbos.com

If you do end up needing a shop we have lots of great recommendations depending on what part of town you are on.