Weird boost issue
 

Have my CRX LS-T t3-t4 internal wastegate, but i have a weird problem with boost.

In 1st i get around 5psi
2nd around 12psi
3rd around 15psi
4th around 13
5th got 10psi again

Internal wastegate Changed, with same problem, the wastegate flapper opens freely, no problem.

What can cause that?

Re: Weird boost issue
 

bumped ttt because i'd like to know why this would happen.

at what rpms are you shifting on each gear? maybe its because the internal wastegate hole is small and needs to be ported.

Re: Weird boost issue
 

you should try using an external wastegate. or it might not even be that could be a bad boost controller(if your using one).

Re: Weird boost issue
 

That would make it creep. Not varied boost levels.

+1

Internal gate might have too soft a spring or other issues you cant see. I agree with drupie the boost controller might be having issues as well. Ballandspring boost controllers are subject to this problem when the spring is too weak or the ball isnt seating correctly.

Blowoff/bypass valves can also cause this issue, leaking under certain loads (ie. 1st gear-low load)

Re: Weird boost issue
 

post your complete setup.
what kind of manifold?
what kind of boost controller? manual or ebc?
where it it set to?
what spring are you using in your wastegate?
exhaust? etc

ive seen more problems with finicky electronic boost controllers more than the manual ones. im sure quality varies depending on the type of ebc, but more to go wrong with.

Re: Weird boost issue
 

No boost controller
T3/t4 internal wastegate (volvo t3, 8 psi)
cast iron manifold with external wastegate tapped
the flapper from turbo moves freely
dsm blow off

Attachment 15777

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Re: Weird boost issue
 

nice car. ditch the ebay special please.

Re: Weird boost issue
 

The reason you are getting different boost values is because of boost creep. 5psi in first sounds fine to me then the extra pounds in the other gears is because of the creep. Just look at it as free extra power since its gated at 8psi.

That or maybe you have a piece of ---- boost gauge

Re: Weird boost issue
 

:8
dont look at that as "free" power. try an external gate.

Re: Weird boost issue
 

if its creep, why then does it make only 5psi in first?