Why Is It Overboosting????

[gstspyder53172]

I was wondering why my boost goes all the way up to 20PSI when I put full throttle in 1st and 2nd. I have the stock t-25 and my only mods are a type RS BOV and intercooler piping and the free BCS restrictor mod. If i'am not mistaken the maximum boost on a T-25 is only supposed to go up to 18 PSI. So why is my going to 20 PSI? also it goes up to 20 PSI and then drops back down to 16 PSI. WHY??

 

[GTR-33]

I was wondering why my boost goes all the way up to 20PSI when I put full throttle in 1st and 2nd. I have the stock t-25 and my only mods are a type RS BOV and intercooler piping and the free BCS restrictor mod. If i'am not mistaken the maximum boost on a T-25 is only supposed to go up to 18 PSI. So why is my going to 20 PSI? also it goes up to 20 PSI and then drops back down to 16 PSI. WHY??

Do you have everything hooked up correctly? Is the vacuum line to the wastegate hooked up? The wastegate is what controls the boost. Unchecked it will go as high as it wants to...

 

[gstspyder53172]

how do you check to see is the wastgate is working?WTF

 

[fwdeclipse]

There is a vacumn line that hookes to a nipple on the actuator,it then tees off and another vacumn line goes to nipple on the turbo.If those are unhooked you will run max boost.It falls off cause the t-25 cant hold boost.

 

[coving21]

16 psi is about it with a t-25, anymore boost then that and it will just drop back to 16 or 15 psi. I agree check your vacuum lines make sure there hooked up. What kind of gauge are you using to measure boost does it point to zero when the car is shut off? Also if all vacuum lines are hooked up then it could be that you have a messed up wastegate and will need a new one.

 

[FastGS-T]

The boost spiking you have is normal on such a small turbo in 1st and 2nd gear. Just turn your boost down so that it doesnt spike over 18... 15psi should be what you need to run on it. It wont hold 10psi over 5500rpms anyway. Good Luck!

 

[luvmygst]

The boost spiking you have is normal on such a small turbo in 1st and 2nd gear. Just turn your boost down so that it doesnt spike over 18... 15psi should be what you need to run on it. It wont hold 10psi over 5500rpms anyway. Good Luck!

HE should not be spiking with the mods he has, and no mbc. I would check the line to the wastegate. When you did the bcs mod did you get every thing hooked back up right? I would run a line from the turbo staight to the wastegate and see if that solves the problem. then go from there. It sound's like you have a leak in the line going to the wastegate.

 

[dalatinromeo]

HE should not be spiking with the mods he has, and no mbc. I would check the line to the wastegate. When you did the bcs mod did you get every thing hooked back up right? I would run a line from the turbo staight to the wastegate and see if that solves the problem. then go from there. It sound's like you have a leak in the line going to the wastegate.

Yup, what he said ^^^.

 

[gstspyder53172]

I have an autometer boost gauge and it seems to be working fine. Iam going to go check my hoses right now I'll tell you what happened.

 

[MoparTurbo]

I think just about everyone has had a damn overboost problem before, shit sucks.

 

[gstspyder53172]

I checked all of my hoses and they all seem fine and they were all connected except for the one that runs to the intake from the BCS restrictor. Even though I connected it back it still Peaks at 21 PSI

 

[luvmygst]

Run a line from the turbo staight to the wastegate and see what happens, you have a leak somewhere, ive seen this before. I bet when you run staight to the wastegate you will only have 8-10psi, unless you have a bad wastegate. Then start over with the mbc install.

 

[eclipsegsx1736]

My BCS restrictor decided to clog itself one day. Do what the others said above, remove the vac lines from the turbo and the wastegate, and hook a single vac line from the nipple on the turbo directly to the wastegate, nothing else. You will run the lowest boost possible in this setup, probably 9-12 psi or so depending on backpressure, unless the wastegate is damaged. , in which case it will still spike high.

EDIT: Oops, didn't see the above post.

 

[gstspyder53172]

Iam going to have to try that I'll tell you'll what happens

 

[GTR-33]

how do you check to see is the wastgate is working?WTF

Like others have stated there is a vacuum line that T's off from the compressor size of the turbo to boost control and then back to the wastegate. When the pressure inside the line reaches the pressure that the wastegate spring is rated for, the flapper will open letting exhaust partially bypass the turbine wheel. You could check this very easily. Blow into the line and you should see the rod from the wastegate to the flapper move. You should hear a little click. If you can't blow hard enough, just use some pressurised air.

 

[kottyking]

How do you have your vaccum line/s hooked up on the rs bov??

 

[Talon96]

put the damn BCS back on. the reason its on there is to cut off boost under detonation/knock. free mod or not, i wouldnt risk 1-2 PSI increase to have to have my engine rebuilt.

 

[eclipsegsx1736]

...Please hook the turbo directly to the wastegate and report back. He already has it hooked up to the BCS and is having problems. We're trying to see if there's a problem with his BCS, and to see if his wastegate is working properly.

 

[kottyking]

Are you sure you didnt loop the bcs?

 

[gstspyder53172]

I have connected a line straight from the wastegate to the turbo and my boost peaked at 10-12 PSI. So I guess my wastegate still works? and does this mean my BCS restrictor is clogged?

 

[delta448]

That is how my car was setup when I bought it. Yes, your wastegate is fine if this produces only 10-12psi. I think your BCS is the problem.

 

[dealz]

its funny i was having the same prob weeks ago with mine. what i did was i made a hole in the j pipe coming from my turbo and put the nipple there (other steps are neessary but you have to have the right tools ) and ran the line for the actuator to that new nipple. if youre wlling to try it i will give you detailed info but you might want to make sure it not just a bad wastegate

 

[gstspyder53172]

So now that I know that my BCS restrictor is bad can I just go ahead and put a MBC in place of it. I have a Turbo XS MBC but I never put it on because I read that you can't really raise the boost that much on a T-25. But I can use the MBC as if it were the BCS restrictor right? Or would I have to buy a BCS restrictor from the dealership?

 

[ECLIPSEGST25]

Make Sure That The Hose On Your Wastegate And Your Turbo Aren't Torn Beacuse If Boost Leaks From Their It's Almost Like Running Open Boost.

 

[delta448]

So now that I know that my BCS restrictor is bad can I just go ahead and put a MBC in place of it.

Yes.

But I can use the MBC as if it were the BCS restrictor right? Or would I have to buy a BCS restrictor from the dealership?

You can use the MBC in place of the BCS. Just leave it turned down, so that you only push a few psi over the wastegate actuator's spring rating. I also have the Standard Turbo XS MBC myself, and it is VERY VERY TOUCHY when adjusting so be careful. When I recently adjusted mine, there was about 1.5 turns between 14psi and 20psi.