Hi guys. It’s been a while since I’ve been on the forum, and I’ve upgraded. 2007.5 6.7 6speed.
It’s got all the goodies and go fast parts on it and I’m actually having a very troubling issue that I can’t wrap my head around.
So I’ve got a boost pressure leak.
When I purchased the truck, both the boost and exhaust pressure gauges stayed 1:1 to full throttle, redline. Which was around 58psi, I am able to peg the gauge though.
Now. My boost pressure will not build passed 44psi and my exhaust pressure will continue to build pressure as I accelerate until it pegs the gauge and then some, toward the end of the rpm range. Which is 2700, while the boost maintains a steady 44psi.
I have done an intercooler pressure test. From the boot right after the turbo to the boot before the intake manifold.
Pressurized it to 40psi and it held for 2-3 minutes. At the end of the test I lost 3-4psi.
Is that something worth digging into? I Could not hear any leaks. So I’ve dismissed that as being the culprit. If I am wrong, please correct me.
That leaves the turbo and manifold.
I checked to see if the bolts on the manifold were tight and they were able to be tightened more. And I tightened them to German “good’n’tight” specs. Still the same issue.
The air filter is about a year old. And the turbo has no play but some resistance on a cold “spin” test. I will check when the motor is hot and fresh oil is lubricating the turbo. The turbo is a double batmowheel s366 That has maybe 50,000 miles on it.
Intake horn is custom, which leads me to believe there may be a crack that I am not seeing in the welds...
So before I go digging, I’m asking for the forums help. Thanks.