20psi spike on STOCK TURBO

[_-Ax-_]

I just put a Greddy knock off BOV on my Talon. Went out for a few pulls and it spools insanely fast all the way to 20 then falls back down to 16 all the way to redline. Yesterday, I had the stock BOV on it and it spooled normally to 12 like it should. My mods are only a modded wastgate control solenoid and 3 inch exhaust O2 housing back....

?????????

 

[regulator213]

do you have a boost controller? What is a wastegate control solenoid? Are you talking about the BCS? if so thats where i would look first. your BOV does not control boost. It just lets the extra air in the intake system vent after closing the throttle plate in the TB.

 

[_-Ax-_]

Yea man I know what a bov does..

Boost control solenoid, wastegate control solenoid, same thing...

I did check the solenoid. Took it out, looks fine. The wastegate opens because it falls back down to 16 rather quickly. It's almost as if it outspools the wastegate for half a second.

 

[regulator213]

Do you have a MBC?

 

[_-Ax-_]

No I'm on the stock BCS

 

[MidShipCivic]

When ever you mod the exhaust on a DSM the boost will creep like this/ You have to port the turbine housing to adequately bypass.

 

[dsm-onster]

I don't think it's creep. He's spiking. The t25 isn't exactly known to creep. He said it goes back down to 12 right away and holds

I suspect that your stock bypass valve was blowing open before. Now with a better bypass valve, you're turbo isn't trying to overcome the massive leak from an open valve and the manifold is filling with the boost spike instead of venting it through the bypass.

IOW, this means that possibly the whole time you've been having a boost control problem, but only a decently sealing BOV showed this up. The stock bypass likes to blow open completely after 15-16psi.

1) Could be the wastegate actuator is sticky. It sticks for a moment while on boost causing the spike.

2) Or the BCS line from the manifold or to the wastegate is broken or has a hole. Once the leak can't vent enough air to keep pressure to the actuator low, the boost suddenly returns to normal.

 

[MidShipCivic]

I just put a Greddy knock off BOV on my Talon. Went out for a few pulls and it spools insanely fast all the way to 20 then falls back down to 16 all the way to redline. Yesterday, I had the stock BOV on it and it spooled normally to 12 like it should. My mods are only a modded wastgate control solenoid and 3 inch exhaust O2 housing back....

?????????

Okay I missed this I thought how are you generating 12, it's because you did the BCS mod.

It's almost as if it outspools the wastegate for half a second.

Your wastegate actuator may be filling up with pressure too slowly, thenyour boost climbs beyond set boost, and then gets vented from a delay in valve opening or like dsmonster said you're actuator hanging up on something,

 

[jrohner]

The WGA rod could be bent, putting more 'pull' on it. People often do a similar mod to hold more boost but sometimes all it does is crate a boost spike. Take the actuator arm off the wastegate flapper, and make sure it only has to be pulled slightly to be put back on.

Are you using the stock boost source (right at the turbo) or somewhere else? Also, look for cracks/kinks/restrictions in the line.