I have a b18b fully built turbo running 14 psi and tuned with 333hp. I have a obx intake manifold that did not have any where to hook up a IACV. I created a vacuum manifold for a vacuum source made out of a 6" pipe with caps on the ends and fittings for the vacuum lines. On my boost gauge at idle it reads 8 vacuum pressure. Instead of reading 20. There is no leaks coming from the manifold i made anyone have any idea whats going on? Is it the size of the vacuum manifold? thank you in advance.

 

anyone please?

 

there must be a leak, thats the only thing that could explain it, especially that much of a change. i've added a vac mani to my car and there was no change in vac readings

 

which line did you tee into?

 

 

Am I correct in assuming you're vac readings are from the boost gauge and not the MAP sensor that's still on the throttle body? If so, it's the vac manifold. I'd venture a guess the "to intake" line is way too small, and/or the iacv is trying to open up too far. You need at LEAST a 3/8" line for the "to manifold" line.

 

wait is the "to intake" going to the air intake or the intake manifold??? if you have a vac line running to your air intake then thats your problem.

also to me it looks like the "main line" is the only one attached to the intake manifold and that line is too small. you basically have a 1/4" line running 4-5 accessories. no beuno

 

Ok thanks i'm going to try that out with bigger fitting and hose.