Odd EGT/Boost problem

[Cattletrkr]

Lately I've had trouble building boost. With all boxes out I sometimes have trouble hitting 25psi. With the Juice in and on level 0 I experience the same thing. Sometimes when I crank the Juice to 3, I struggle to hit 30. I keep saying "sometimes" because every now and then when everything is working properly, I can hit 38psi with the Juice set to "0". There doesn't seem to be any rhyme or reason to it.



The EGT will climb easily to 1300+ relatively quickly. If I can ever get the boost to max out, the EGT will drop to a safe level and stay there until I back out of it. Usually I end up backing off long before the boost gets up high enough because it's getting too hot--1400*.



The Juice seems to be working as I can tell an obvious SOTP difference in take-off and hill climbing ability with a load. However, I have virtually stock smoke levels regardless of what level the Juice is on. The lack of smoke leads me to rule out a dying turbo.



I not laying this on the Juice because the truck still won't build boost to stock levels with stock fueling. It's just a lot more noticeable if I use the Juice to dump fuel in. EZ is out until I can get this figured out.



Do I maybe have a goofy MAP sensor? No codes. Fuel Pressure gauge tells me everything is fine with the LP and fuel filter.



If I didn't have gauges I wouldn't know anything to be wrong. Truck sounds/acts normal otherwise

 

[cerberusiam]

A rail pressure reading would help rule out relief valve, FCA, etc.

 

[LEPage]

How 'bout something as stupid as a boost hose leaking or loose? Just a thought.

 

[p-Bar]

Lepage may be on the right track. I've read to spray shaving cream on the couplings ect, it will show you the leak if any. What year is your truck? Does it have plastic tanks on the intercooler?? . Pull of the boxes and see how it is stock 25-28 psi

 

[Cattletrkr]

I forgot to mention the truck was at the dealer a week ago for this. They ran every test they could, the first of which was to pressure test the intake system, no leaks. The service manager and I went for a test drive with the computer hooked up. Everything checked out perfectly normal. However...

A rail pressure reading would help rule out relief valve, FCA, etc.

... that's the one thing I don't know if anyone looked into.



The Juice was out for about 600 miles after the trip to the dealer and nothing changed. That's when I decided to re-install the Juice. The first hill after re-installation I ran on either 0 or 1 and I held 72mph with 38psi and 1275*... perfect. Didn't work the next 450 miles to home.

 

[LEPage]

Figures a boost hose leak would be to easy. Are you sure nothing is wrong with your gage? Just looking for the easy to fix stuff.

 

[Cattletrkr]

Figures a boost hose leak would be to easy. Are you sure nothing is wrong with your gage? Just looking for the easy to fix stuff.

Which one? The autometer on the dash or the one in the Attitude that reads the same # as the dealer scanner?

 

[Cattletrkr]

A rail pressure reading would help rule out relief valve, FCA, etc.

What are "normal" pressures for empty cruising, light acceleration, WOT, etc? I remember seeing the rail pressure readout from a dealer trip once. At idle my truck was sitting just under 7K. That was a while ago. Hopefully by this afternoon I'll have my gauge installed and ready to roll.



Before I install the gauge I'm thinking about removing the FCA and making sure everything is clean and corrosion free and connected properly. Is there a way to test the FCA short of a trip to the dealer?

 

[Cattletrkr]

Phone rang and I ended up going to Iowa yesterday. Got the gauge (rail pres. ) in today. Went for a little test tonight.



With Juice on "0".

--Idle 6K

--moderate accel 15-17K,

--all out go 23K.

Max boost 24psi



Seem to be inline with what I seen posted.



With Juice on "3"

Idle and moderate were the same. All out still maxed out around 22K. Kinda hard to keep an eye on the gauge at 80mph tho. Max boost 26 psi.



Got back home and idle psi was just shy of 7K, vs 6K while it was warming up.



It was dark so I couldn't see what I was getting for smoke, but at -2*F it would have all been white anyway.



I took the FCA off and everything looked good. Not sure if that really proves anything though. I though I read somewhere that it should rattle? Mine didn't.