7.3 boost issues

This started this fall and I've been trouble shooting and testing parts for months with no progress. Truck is a 2000 F350 7.3 6spd dually.
Current mods are:
250/200
studs
push rods
valve springs
stealth hpop
php tunes
swamps idm
airdog 150
regulated return
south bend dd
intake
5" straight exhaust

As you drive down the road it starts to build boost once it gets to 23lbs if driving gently it will drop off to nothing almost instantly. If you drive and shift hard it will only build around 15lbs before nothing. When I say nothing there is a loud woosh and the gauge drops to 0 and it starts smoking like a chimney. Then I shift and its all back to normal until I get to the same boost range. Over the time this has been going on I've installed new IH bellowed up pipes, push rods, and valve springs, a new 38r, new riffraff boots, ICP sensors. I've also swapped intercoolers, map sensors, computers, tuners,injectors, hpop, tried eliminating my boost fouler. This was going on with both stock injectors and my large 250/200s. my old 38r had many miles, I tried bolting the waste gate shut and got no change, tried a stock turbo and it seemed good for a couple days then back to loosing boost as if a waste gate opened or boot came off. Now I have a brand new 38r and no change. Are there any sensors I should test To see what is going on? I have an AE but I'm totally out of ideas and places to look at this point. Its definitely not defueling, no check engine lights.

What does the fuel pressure look like when this happens?


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Gauge stays steady. My regulator is set at 70.

What is your intake setup? Sounds like you are collapsing a rubber boot and cutting off your air.

I'd second that

38r intake to factory plastic piece on valve cover to factor rubber piece that used to go to air box then an aluminum tube with the filter on the other end of it.

Pull off the intake tubes to the turbo and go for a quick ride. If it still does it check for turbo play shaft play. Like they said, either turbo boot is collapsing or the turbo is stalling.
I could get my 38r to stall by lugging it up a hill

Missed that you have a new 38r. Try pulling the intake off

I will try that. This turbo only has. 50 miles on it. Thought for sure it was just worn out old turbos but brand new does the same thing

What's your filters condition? What kind of filter?

Looks like it was the intake. Took it off for my ride to work. It will lay the gauge over on the peg and stay there till I lift. I'd guess that short section of factory rubber was collapsing. Thanks for the input everyone.

If your stuffing aluminum into that 3" long rubber boot, it's more likely you're collapsing the silicone boot that came with the 38R. I'm interested in what filter, and it's condition.

Edit:
You may be using more than what I thought. Regardless, you may need a less restrictive filter. So what are you using ?

It has a western diesel ram air kit with a k&n filter. I just cleaned it.

While I've never heard of said ram air kit, if you like you're shiney new turbo, I'd get a different filter asap, k&n are notorious for letting large enough particles passed to chew up the compressor wheels on the turbo. If you had that long on your old turbo, look at the outer edge of the compressor inducer, I'll bet you'll find it quite rounded compared to your new one.

Edit: I run and like my s&b with a dry filter but even a cheap tymar filter does well.

1ofakind79 said:

It has a western diesel ram air kit with a k&n filter. I just cleaned it.

Click to expand...

Never heard of that intake, is it an open filter or a closed setup like S&B?

It's old. It's been on the truck since 2001. I believe the company is now out of business. Its is similar to s&b but has an additional ram air portion that goes behind grille in through the hole in core support. It also turns the left battery 90° so air flows past it rather than around it to get to the filter. The plastic ducting is all nice. It seems my issue it a section of rubber from the valve cover area to the filter. I've ordered steel tubing to make a new piece to couple it all together.

Id still recommend ditching that K&N for any other filter basically. If you like your turbo.

More like if you like your cylinders having compression.

throw a napa 6637 in there and try it..

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