Overboost/ spike issues

[NickGT20]

I installed some gauges last night on the ol' girl and to my suprise and shock the car is spiking to 20 psi and it's running at about 18 psi. There is nothing done to it.. I mean bone stock. It does have an aftermarket BOV b/c I accidentaly cracked the stock plastic one. So at first I thought the gauge was wrong, hooked it up to a bike pump and it's within 2 psi of the bike pump. I also have a MBC that needed installing so I installed it and set it to the lowest setting. It's a nice Forge UNOS boost controller ball and spring type. Now the car spikes to 22 psi and settles to right arround 16 or so.. Today I tested the acuator with the bike pump and sure enough right arround 8-10 it starts moving.. So I hooked the acuator up to the turbo psi outlet off the elbow and drove arround sure enough the car will spike to about 12psi and settle at 9-10... I took apart the MBC which comes with 2 springs and made sure the lightest one was in there, I then cut out 2 spring coils to lighten it more.. Same thing. It is hooked up per the instructions with the bottom refrencing boost and the top to the acuator. Anybody know why I'd have so much trouble.. I will say in testing the MBC with the bike pump it seems like a lot of the air escapes out the drilled in hole in the body, I dont know if that is normal?

 

[Tsi2nr]

What kind of Aftermarket BOV is on the car right now? Is it recirculated?

 

[diablos991]

My guess is that something is installed incorrectly.

There should be nothing spliced into the BOV line. It should have its own pressure source.

Also, make sure that the right lines are connected to the right places on the boost controller. One will go directly to the wastegate, and the other will go directly to the compressor housing on the t25.

Also, be sure that your boost gauge is installed correctly.

EDIT: Here is a link on how to install the MBC
Here is a link to a DIY on this site for installation of a boost gauge.

 

[DGajre777]

Did you T off your Blow off valve or use the nipple on the T25 turbo compressor for your boost source? You are supposed to use the compressor nipple for a boost source on the T25.

More info here - http://www.dsmtuners.com/forums/showthread.php?t=237982

If you took your boost controller apart, it should be inside of BOV > Spring > ball > boost source (compressor nipple). If you have the ball after the spring, you'll get a spike.

 

[NickGT20]

i didn't T anything I just used the comprosser nipple and the wastegate acuator. I plugged all the BCS nipples with vaccum caps just in case. Right now I have the comprosser nipple directly to the Acuator and it runs about 10 psi now. As soon as I use the boost controller I cant get it below 15ish psi and the car spikes when I lean on it. The boost controller is put toghetor properly and installed correctly. Is there anyway to test a boost controller for failure? When I hook a bike pump up to the pressure side of the boost controller where the T25 nipple would connect and pump almost all the air goes out the hole in the side of the boost controller. Cranking it tighter just makes that happen at a higher psi than the lower setting. But most of the air is escaping to atmosphere through the hole and not going to the acuator which is what should happen i'm guessing. Also why would teh car be running so much boost before the boost controller when I used the BCS crap. And it was running that much psi I hooked up a known good gauge to another boost source and same result. How can the car not have hit fuel cut and the turbo not have gone bad?

 

[nightspeed87]

couldve been on its way though... Im guessing you dont have a logger or you wouldve already known you had a problem... So you didnt do anything to the exhaust at all?

 

[NickGT20]

Nah everything is totally stock. Do you think I ruined anything? I ordered a dsmlink but it hasn't come yet. By changing out the hoses I was using from the acuator and the compressor nipple I was able to limit the boost spike with the boost controller. It's weird it's not WOT that is spikes really. It spikes to about 16psi now and settles arround 11ish and in between gears teh boost goes up to about 14psi. It's an automatic. Is this normal? I want to raise the boost so it'll hold about 14psi across the board but i'm afraid it'll spike higher.

 

[patty AT forge]

Cutting the coils off of the spring might have converted the MBC into a non-adjustable bleedvalve, the spring needs to be long enough for the ball to seat against the bottom half of the boost controller body. If this isn't happening the MBC will continuously bleed boost.

Here is a test that you can perform:

Cap off the side port of the MBC and apply pressure to the bottom port, if the valve is opperating correctly you should be able to hear and feel the ball cycle very quickly and the pressure applied to the bottom port should bleed out of the hole in the side of the MBC body. If the pressure continues to climb or bleeds out without cycling then there is an issue.