Low boost

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Aug 14, 2019 | 03:55 PM

green_95

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Tuned

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Low boost

Drove my truck to work this morning and all was fine, and on my drive home it felt sluggish. I have a scan gauge II hooked up to it. If I get on it super hard I can make it to the low 20's, but normal crusing it is around 5-8 lbs and quickly drops below 1-2lbs when I let off the throttle even when going 60mph. I ain't had my truck long so I dont know it well yet, but this just seems off. It could be in my head, i am a paranoid kinda person. Its bone stock except for the egr delete, the only code I'm getting is the p0401 for the egr delete. I have replaced the cold air cac plastic tube with a metal o e and new boots but I did not the passenger side one. Where it attaches to the intercooler is all covered in a film of oil. Am I crazy, or any suggestions on where to look?

Aug 14, 2019 | 04:09 PM

Collision

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Joined: Feb 2016

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From: Royersford Pennsylvania

If it's covered in oil that's probably the one that blew

Aug 14, 2019 | 05:41 PM

green_95

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Quote:

Originally Posted by Collision

If it's covered in oil that's probably the one that blew

I'll start with that and order a set from riff raff, they ain't cheap.

Aug 15, 2019 | 04:59 AM

npccpartsman

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Joined: Dec 2003

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From: Stuttgart, Ar

The factory hoses "bleed" for whatever STUPID reason. I've bitched about it for 15 years and was always told it was normal. The only problem I've ever had with them is splitting from old age/wear. A leak will be fairly obvious. I think what you're seeing is fairly normal for a California flashed truck. One other thing you can try is simply disconnecting the battery cables for a few minutes and turning on the headlight switch to clear the KAM capacitors in the PCM, then just let it do a relearn on it's own. Study the boost numbers while it's relearning and I think you'll see it's pretty normal.

Aug 15, 2019 | 06:56 PM

navistarnut

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Joined: Aug 2015

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From: NW IA

You might also take the hose off of the MAP sensor to inspect the nipple.
If it's gunked up it will affect boost as well.

Just take a chunk of weed eater line and run it thru the neck into the intake to clear it of any possible junk.
I would also inspect the hose itself for any cracks, etc. I did replace the hose on the kids truck a few years ago due to age and getting really brittle.

All that said, you won't see much boost with no throttle, the demand is not there.

Does the truck seem low on power?
Lower 20's is normal for some owners. You might also check each and every joint from the exhaust manifolds up to the turbo for any carbon tracking.
Even a small leak at any joint will rob you of a few lbs of boost.

Aug 15, 2019 | 10:36 PM

knotreel

Mountain Pass

Joined: Dec 2004

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Mine is an 03, and uses inferred strategy instead of EBP for VGT calculations so my experience may not be that helpful to you, but mine briefly will do 20 ish and drop back to 18 boost under unloaded WOT. I could never fix that after much fiddling but finally when I towed a 10,000 load up some bridges it got 28 sometimes and always can get 25 even backed off a little. Your cruising numbers look what I would call, typical. So perhaps your truck is like mine in that it cant make the boost other people talk about unless it is under full towing load. 18 boost won't win a race but really is plenty as long as you can get mid 20's while towing . My theory is that the 03 and early 04's using inferred strategy are a little messed up boost wise. I suspect it was one on the factory flashes that did this, maybe the flash that set it up as inferred rather than using the EBP like it was designed for. After 04, they fixed the EBP system and switched by to that. You probably should get a monitor or set up or forscan to see what is going on under the hood.Things in case of low boost are VGT duty cycle, EGR ( and you already have a code ), EBP (if your truck has that). Leaks, you are already looking. Temps and so on.

Aug 16, 2019 | 10:22 AM

green_95

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Truck is a 06 with 103k miles. It just seemed like before I'd hit the low 20's without trying real hard and now I have to really romp on it. I ordered new boots from riffraff, they will be here tomorrow, the lower hot side boot is really oily, hoping it just blew out.