I got my gauges installed last night (Isspro pyro/boost) and seemed to found part of the problem with my low power. Running down the road at 60 mph, the guage sits on the peg. Running down the interstate at 70 mph it pulls up off a little to around 2 psi. If I flog it very hard and endure all of the black smoke, and leave my foot in it for awhile, I am lucky to hit 14 psi. My egts are around 1100 full throttle also. I did an air test on the charge system of the truck and found my waste gate diaphram was ruptured or leaking badly. Once I pinched that, it would hold 10psi, so I am thinking maybe an air intake horn leak? Is there a way to tell if the intake gasket is shot? If I tried to air it up anymore than 10 the clamp would try to slip off the turbo, any suggestions on how to better test that?

 

if you need to replace it here are the part numbers.

Cummins P/N 3969988
From Dodge it is called the Air Inlet Gasket; it is part number 5010480AB.

 

Disconnect the wastegate signal line from the AFC and the turbo. All aftermarket turbos run the signal off the compressor housing anyway.

At 10 psi, you should be able to find most leaks. Get out the soapy water and watch for bubbles.

 

The line to my AFC housing comes off of the intake manifold, by where I tied in my boost guage between the P7100 and the block. Is that the one I need to disconnect?

 

My boost leak tester wedges against the oil filter housing to keep it from flying off.
10 psi is enough to find a manifold or innercooler leak with soapy water though.
Plug off the wastegate line at the turbo, much like you pinched it.
1/4" bolt and a hose clamp works too.

If I'm understanding you right I don't know that I would trust where you plumbed in your boost gauge.
Better place below.

 

Infidel, I did place the boost gauge connection where you said when I installed the gauges. I messed with it a little more today and pressure tested the system again. What I found is that 10 psi will leak out of the system within 30 seconds. I sprayed everything with soapy water and found some small leaks on the boots going into the intercooler, but they were very small bubbles. It wasn't where the clamps were but coming through the rubber itself. Would this be enough to cause my problem? Where is a good place to get replacements? I do not want high high dollar ones, just some OE type. I was thinking that I am looking more for a large leak, not a couple small ones.

 

To add to this, I went out today and took my plug out of the intake horn boot and just pumped up the whole intake and the engine. I bumped the starter to try and find a spot with no valve overlap and got it to the point where I thought it was the best. I could find or hear no leaks except for the oil cap hissing a little. When I climbed underneath the truck, I heard alot of air coming from the oil pan area. It will almost leak out just as fast as I can put it in. I struggled to get 15 psi in it a couple of times but my intake horn and intake gaskets all semed to be holding. What am I looking for now?

 

I also found the turbo is hissing just a slight bit, but its enough for me to hear it leaking through the exhaust. I don't know if that provides any clues or not.

 

Pull the valve covers off and back off the valves. That will keep the air from entering the cylinders. Boost it up. You could have leaky valve seals which would account for the air you hear in the crank case, plus if you have a couple open intakes, then it will be blowing past the rings as well.

 

I don't think I need to do that, I can get enough pressure up without tearing it all apart but I cannot find a boost leak anywhere.

 

If I do end up doing that, how hard is it to readjust the exhaust valves when its time to tighten them back down?