New sticks plus tunes, truck falls on it's face

[maplemale]

Preface by saying, I tested fuel pressure already, holds around 60psi WOT.


Recently put new sticks in. Rebuilt myself with 30% over at Bitteroot Diesel (nice having family with a shop!). Also did a CNC Fab stage 1 HPOP, new transmission with tugger kit and billeted converter etc, rebuilt fuel system minus the pump (pressure reg, bowl, seals etc). Rebuilt IRP while I was at it. But, now we've got a new issue when accelerating hard and would like to ask my fellow 7.3 guys for some input.


Does this seem like tuning, de-fueling? I didn't expect to need a new fuel pump with only 30% over, maybe I'm naive though.

Description:
Near WOT: Falls on in it's face half-way through curve usually around 2.2k RPMs . The IPR goes from 2500psi approx and instantly buries itself in a millisecond at 3800psi while truck dogs/lacks 75% of power. After maybe 2 seconds it snapps out of it / pulls hard and the IPR goes back to a 2800-3k psi and climbs to 3500psi, pulling hard / as normal. Only occurs at WOT or near WOT. Does NOT occur during medium / average acceleration. Most noticeable in 2nd - 3rd gear. My fuel pressure gauge holds fairly consistent during all this. This is FAR less noticeable in my street / all out tunes than daily driver.


I've already reached out to Gear Head but wanted to see if I'm missing something obvious before I waste too much of their time. Seems like tuning, but maybe just plain lacking fuel. Odd how my Fuel pressure stays consistent around 60 psi during this. More odd to me is the way the IPR acts. PS: Did this right after new tunes and sticks. Put the new HPOP in as well and rebuilt IPR afterward, and made no difference. Still dogs at WOT for a couple of seconds.


Thanks for input!

 

[Magnum PD]

Need to see what the duty cycle is.

Might have something behind the edge filter.

 

[mcnance865]

Have you gotten all the air out of the system? How many miles since injectors and/or hpop install?

 

[dieselmandustin]

Not saying this is your issue but i had the same thing happen to me years ago. Turned out on a hard pull it would empty the oil res. Wot truck would fall on its face. If i stayed in the throttle it would die out like a dead pedal for 2-3 seconds then all of a sudden come back to life.

 

[dieselmandustin]

Also icp would do exactly like your saying. My issue ended being a bad cover. I had replaced the cover with a new Ford cover and the oil passage coming from the lpop to the res was restricted due to bad casting. Im sure the cover is not your issue since it ran fine all these years but the issue your having sounds exactly like what mine did. You could possibly have a weak or worn lpop. Just throwing ideas out there. Hope you get it fixed.

 

[maplemale]

Need to see what the duty cycle is.

Might have something behind the edge filter.

I'll test this on the way to work tomorrow morning. "Edge filter'? I don't remember 100% for sure, but I want to say it also buries itself at 50% as soon as it happens. Normal / semi hard acceleration that HPOP never breaks 34% ish. All the way up to 3400psi+. Also, keep in mind it did this before I replaced the HPOP. Part of my reason for replacing it (aside from high duty cycle) was because I thought this was root cause of the issue.

Have you gotten all the air out of the system? How many miles since injectors and/or hpop install?

3k miles since new injectors and HPOP. Assuming it's all out...

Also icp would do exactly like your saying. My issue ended being a bad cover. I had replaced the cover with a new Ford cover and the oil passage coming from the lpop to the res was restricted due to bad casting. Im sure the cover is not your issue since it ran fine all these years but the issue your having sounds exactly like what mine did. You could possibly have a weak or worn lpop. Just throwing ideas out there. Hope you get it fixed.

Cover - as in a valve cover? That would be interesting... had em powder coated while they were out! LOL

If it's the ICP I suppose I could easily test that by unplugging it and running without. Doesn't it give a constant high reading when that thing is unplugged? Like 2500 psi or something? I wonder if this could also be CPS related. I don't have a spare right now, I used it up when the truck died a few months ago on logging road and turned out to be CPS. I should grab a spare regardless and try swapping it.

 

[gwunter]

He means the front aluminum cover on the engine. The one the water pump, lpop, etc bolt to. Basically the lpop can wear the front cover out and it won't give oil supply the way it should.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[lincolnlocker]

I'll test this on the way to work tomorrow morning. "Edge filter'? I don't remember 100% for sure, but I want to say it also buries itself at 50% as soon as it happens. Normal / semi hard acceleration that HPOP never breaks 34% ish. All the way up to 3400psi+. Also, keep in mind it did this before I replaced the HPOP. Part of my reason for replacing it (aside from high duty cycle) was because I thought this was root cause of the issue.




3k miles since new injectors and HPOP. Assuming it's all out...





Cover - as in a valve cover? That would be interesting... had em powder coated while they were out! LOL

If it's the ICP I suppose I could easily test that by unplugging it and running without. Doesn't it give a constant high reading when that thing is unplugged? Like 2500 psi or something? I wonder if this could also be CPS related. I don't have a spare right now, I used it up when the truck died a few months ago on logging road and turned out to be CPS. I should grab a spare regardless and try swapping it.

Make sure the cps is motorcraft.

live life full throttle

 

[Lt.Dan]

I think you have IPR and ICP mixed up, because your IPR is measured in a percentage (how far the valve is open) and ICP is measured in PSI (pressure of oil).

And you are saying you are making 3800psi of ICP??? That's borderline dead heading the pump, or you have some gnarly twin pump with an extended reservoir. People rarely see over 3000psi, and are usually around 2800psi. I would be looking into your HPOP/IPR, because something isn't right there.

Sounds like there is a restriction between the pump and injectors, making the pump spike pressure, but then the injectors cant fire because the pressure isn't making it to them.

As stated above, we need to know your IPR duty cycle %.

 

[maplemale]

I think you have IPR and ICP mixed up, because your IPR is measured in a percentage (how far the valve is open) and ICP is measured in PSI (pressure of oil).

And you are saying you are making 3800psi of ICP??? That's borderline dead heading the pump, or you have some gnarly twin pump with an extended reservoir. People rarely see over 3000psi, and are usually around 2800psi. I would be looking into your HPOP/IPR, because something isn't right there.

Sounds like there is a restriction between the pump and injectors, making the pump spike pressure, but then the injectors cant fire because the pressure isn't making it to them.

As stated above, we need to know your IPR duty cycle %.

Sorry, been gone a while!


Yes, typo'd / said that all wrong in first post.


FYI: Duty cycle also buries itself at 50% at the same time I see 3600-3800 psi + loss of power.


Again, this is with a new HPOP from CNC Fab + rebuilt IPR - though maybe I should just toss that and buy a new one? Also, I just purchased / installed a new melling LPOP tonight and still no change. Thought it unlikely to effect it, but worth a shot I guess. So, "bad casting" on the housing? That's an interesting theory but ya, it seems unlikely since it's been 230k miles and this issue just presented itself with rebuilt injectors.

Thanks for your help!

 

[Magnum PD]

Might have a leaking o ring

 

[maplemale]

Might have a leaking o ring

Around what? I mean, what component? No signs of leaks (at least not external) anywhere.


FYI: I also have another tune from a different tuner I use for trouble-shooting just this sort of stuff - it does the same thing.

 

[Magnum PD]

Injectors Under the valve cover.

If the injectors weren’t torqued down right or the o rings may be bad.

 

[maplemale]

Injectors Under the valve cover.

If the injectors weren’t torqued down right or the o rings may be bad.

Not a chance. Just put these injectors in last month with new seals + crush washer etc. Also replaced the cups and torqued everything correctly. I've done 4 injector jobs prior and i'm VERY meticulous. Also, I think there would be other issues if this was the case.

 

[maplemale]

Here's my current working theory and question + a little more info from my test drive last night:

First, some more info: The RPMs climb steadily until until about 2200rpms. At this point, the truck instantly falls on it's face (lacks power), the duty cycle spikes instantly to 50%+ and the PSI instantly spikes from around 2200PSI to 3400-3800PSI. Once the RPMs reach about 2400-2600rpm while climbing much slower than they should, everything goes back to normal. The Duty cycle drops to 30%-ish, the PSI drops to about 2400psi-2600psi and climbs steadily. The power is back and the RPMs start steadily climbing again as expected.


Now, working theory:
Seems to me it's physically impossible for the HPOP to jump from 2200PSI to 3400PSI+ in a nano-second. That's a 1200PSI jump in zero time! Therefore, it seems to me this reading must be wrong. If it's wrong, this must be coming from the ICP? Therefore, the computer would tell the IPR to back off the pressure and you'd instantly lose power. At least, i think that's the function of the IPR... Any issues with that theory?


Now for my (hopefully) final question: How can I validate this is the case without just flipping for a new ICP? I know you can unplug it for no-start issues. But, how is it going to effect things driving around and mashing the accelerator with the ICP unplugged? Also, is it plausible I have a wiring issue / bad ground etc, that could be causing the issue on the ICP circuit or even the IPR circuit?

 

[superpsd]

A few things can cause this I have seen from other issues over the years on the forums. A way to confirm ICP is actually spiking is to run a manual Pressure gauge to where you can see it and confirm. IPRs can cause all sorts of issues and so can Injector problems etc. 3800 icp is the setting on the mechanical overpressure bleed off valve. So it is possible the ICP sensor is receiving correct feedback. Also do you have a motorcraft CPS installed? CPS can cause all sorts of issues.

 

[Magnum PD]

I got a manual gauge if you need to borrow it.

 

[JCart]

Just wondering if you have a boost fooler on the MAP sensor and/or if your tuner has accounted for boost pressure tables? Over 24 psi boost and SD engines de-fuel. What I can see happening without boost fooler, engine hits 25 psi, de-fuels for a millisecond, then reverts to canned (meaning none dynamic) fuel tables that are stored in PCM and carries on to WOT. Boost fooler should limit what the MAP sees to 22 psi.
Just a thought,
j

 

[maplemale]

Just wondering if you have a boost fooler on the MAP sensor and/or if your tuner has accounted for boost pressure tables? Over 24 psi boost and SD engines de-fuel. What I can see happening without boost fooler, engine hits 25 psi, de-fuels for a millisecond, then reverts to canned (meaning none dynamic) fuel tables that are stored in PCM and carries on to WOT. Boost fooler should limit what the MAP sees to 22 psi.
Just a thought,
j

Great thought!

So, I'm using Matt's (gear heads) tunes. I have a 6.0 Map sensor to read the additional boost. I told them about this when i requested the tunes, I'm assuming they accounted for the 35-ish psi I'm pushing.

 

[dsberman94]

I’d put a boost fooler in it with a 7.3 map. Not sure where the idea of a 6.0 map sensor comes from or what that might do to a 7.3 computer. Never even heard of that before. Stock map sensor would still throw a code on my truck at 24 psi. It’s going to go off what the computer sees not what the sensor can read. And I don’t remember whether it would just set the code or do other funny stuff. I also have a different tuning company.

And I’d put a known good motorcraft cps in it too.