Need some idea's here, trying to figure out my buddy's truck. 2004 5.3 scsb, had cam and full exhaust then I put a p1sc on it, it made 7psi with a 3.7 pulley. Changed to a 3.5, then to a 2.8, still only 7psi. Figured maybe the 108 LSA cam was a problem so I did milled 243s and 224/233 114 cam, still only 7psi. Made sence if the blower was maxed out, so we switch it out to a 12 rib belt drive with a f1r blower, has a 4.75 / 7.5 pulley combo on it now, went out and tryed it... Bam 7psi of boost. The recirculation valve was replaced with a big red pc bov, air to air is also replaced with a treadstone unit. What on earth could be regulating the boost to only 7psi? Next step will be to pull the intake rockers off a pressure test the entire cold side, just wanted to see if you guy's could think of anything else it could be before I did it. Thanks

 

With a problem like this I Can almost guarantee its not a problem with the engine or the blower itself. I would have been looking square at the BOV or something...

 

Procharger says there bov is setup to push down 2psi for every one psi of Boost, so the more boost you make the more the bov will overcome the boost pressure in the intake tube. So it "shouldn't" be the bov if it makes any boost at all. And it "should" be work right as its brand new. But I guess we won't know till we do a pressure test.

 

Did you test your gauge?? Does the power feel the same?

 

Is that boost number confirmed by the MAP sensor as well as a manual gauge? Sounds like a big leak somewhere, pressure test will be very useful. How much belt dust?

 

Boost gauge is confirmed with the map sensor, or it was the last time we tuned it anyways, the truck is not at my place at the moment. Have not looked into seeing if had any belt slip, it has the house of boost brackets with the 12 rib belt, I guess there it is a possibility it could be slipping, but the fact that it made 7psi again just like before just led me to believe it was something else. What's also strange is it makes 7psi at every rpm, 4k or 7k rpm its always 7psi. If feels strong on 7psi, its definitely not down on power, but its also not gaining anything either.

 

It has to be something letting air by once it gets to that pressure, cracked intake, sensor, gasket.. I'll get this pressure test done and see what I find. This pulley combo should be making 12-15psi up at the high rpm.

 

 

Well the guy had the day off so I talked him through the process of pressure testing, few hours later he sends me that. Said it sealed up great till 7psi and it opened that crack up on the maf sensor and pushed all the air out!

 

That did not freak the maf out?