Truck Falls On Its Face.

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2000 F-350 SCLB 7.3 4X4 ZF6 :fordoval:

Turbonetics T-4 w/ S468 FMW, Swamp's 300/200%, Swamps Gen3, Irate Comp Fuel, Irate 3" Plenums, ARP Headstuds, Comp 910's, Smith Bros Pushrods, Hydra with Tuning from Gear-Head and Swamps.

My truck falls flat on its face when I accelerate hard and i'm looking for any input or ideas of things to check if anyone has had similar issues or has any clue on whats going on. So if I hold it past 3/4 throttle it will spool and start to pull for about 3 seconds and then boost will drop from around 50lbs down to about 4lbs and nothing will change until I lift. As soon as boost drops it smokes like a freight train and goes nowhere. If I keep it under 3/4ish throttle and under 40lbs of boost it feels great. Fuel pressure never drops below 65psi, ICP never drops, and my IPR DC is at 36% at 3300 psi. It has always done this but I figured ICP was dropping because I had a stock HPOP at the time with everything else in my signature, but I just installed a Gen3 the other day and it pulls a bit harder right before it falls but it still does the same thing. I just data logged it today and below is a captured pull, the first picture is before it falls off and the second is after. One noticeable thing is peak boost on my mechanical gauge is 50lbs, and the most my MAP sensor ever sees in the pull is 39, so roughly 24.3lbs. The other thing I notice that's out of the ordinary is my injector pulse width is 5.18ms at one point, isn't that high? thanks for any input.

Bump


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What are you running for an intake? Did this just happen all of a sudden or do you think it's gradually gotten worse?

I know I have old tunes and still require a manual boost fooler. Do your tunes account for this or do you have a mechanical device installed to limit the boost #'s your trucks computer sees? Sounds like a defueling issue to me, but I'm no mechanic

It feels like it, but if I remember correctly ghead uses the signal from the MAP sensor, I'll try a boost fooler and see what happens, I lent it to a friend lol. I have a Donaldson and I installed my factory filter minder to see if it was a restriction and it hasn't sucked in one bit. Also It has always done this since I've had the 468 on it and have run more than 40lbs of boost, it was brand new from BW in December and I made a boost leak tester and I also made an uppipe leak tester and neither side do, Thanks.


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I'm leaning towards the pcm seeing an over boost and defueling, but It should happen before you hit 50 lbs of boost. I'm not certain but I think the pcm doesn't want to see more than 28 psi, definitely not 39 though lol. I'm not sure about the ability to tune that out you'd have to ask Matt that one or someone here may know. When I hit 35psi in my old truck it would fall flat and sort of buck when it went into defueling. I put a manual boost fooler on and she was golden.

Besides some sort of wierd boost leak that only happens above 40psi I'm not sure what else it could be seeing that everything else is within range.

Matt tunes around the defueling issue for boost.

What RPM's does this happen at. Your truck will defuel at 100 MPH, or at a certain RPM, I think 3100 or so.

It will do this around 2200rpm and above, and if it was de-fueling wouldn't it drastically pull PW? It goes from 5.18ms before it drops to 3.99 after it drops?


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Pull the chip out and see if it still does it.

I don't even think it will boost high enough without the chip in, and it will run like ass cause of the split shot tuning. You think it's worth a try?


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Should my pulse width be that high? Can anything cause it to increase in an attempt to compensate for a fault?

I'm no diesel tech, but if it rolls smoke when the boost drops like a rock; then how can it be defueling? It just seems to me that if the system was cutting fuel then the smoke would clear up as well, not get worse. But I dunno.

I agree! it's like the waste gate I don't have opens lol. I can't think of anything!


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Maybe your air filter is collapsing. Or one of those fancy Scott blue intake chokes. (Rag) Seems unlikely tho.

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I would try it with nothing attached to the inlet of the turbo. I suppose you could be collapsing the rubber intake boot, which would cut off the vacuum completely to your filter minder and not show a restriction on the gauge. It would be an easy test to run.

:whs: That was my thoughts and why I asked what kind of intake your running.

Haha from when I pulled one through? Haha I'll take some under hood videos.


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And then pull my intake off completely and give it a shot


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The one time I pull my intake off and run it, I'll end up pulling a rat through my engine or something.


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Powerstroke1098 said:

The one time I pull my intake off and run it, I'll end up pulling a rat through my engine or something.


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Click to expand...

It will come out the other side..