overboosting - Toyota Nation Forum : Toyota Car and Truck Forums

NU2MR2 · 03-26-2006, 08:56 PM

I installed a mbc on my turbo(just rebuilt and installed) and turned all the way down, so it would just run off of the wastegate, but my boost shot up over 15psi! I thought the stock wastegate was only so posed to let it boost to 12 tops? I don't want to kill my turbo...what can I do?

ST185 · 03-27-2006, 09:48 PM

Make sure all vacuum lines are connected properly, especially on t-vsv side.
Most people forget to plug that port.

NU2MR2 · 03-28-2006, 06:08 AM

I'll have to check that, but I won't get to work on it unntil this weekend. Thanks.

NU2MR2 · 03-28-2006, 03:59 PM

Quote:

Originally Posted by ST185

Make sure all vacuum lines are connected properly, especially on t-vsv side.
Most people forget to plug that port.

Where exactly is this?

***MR2Jedi*** · 03-28-2006, 10:43 PM

what do you mean by-"so it would just run off of the wastegate" ?

NU2MR2 · 03-29-2006, 06:58 AM

The stock wastegate is soposed to keep it under 11.8 psi, right? Well, I figured if I turn the boost controller all the way down; it should run stock boost and I wouldn't have any problems. But it's overboosting...so the wastegate isn't opening right(enough, whatever) so there isn't enough air bypassing the turbo, and I want to drive my car without the fear that she'll blow! Any ideas?

ST185 · 03-29-2006, 07:38 AM

Stock max boost is 11.8 psi when TVSV is open.
Normal boost range is 7.1-11.8.

There are two vacuum ports on the wastegate actuator.
One is connected to the compressor housing.
This is the one you should connect it to the MBC.

The other port is connected to the t-vsv.
You need to disconnect the hose going to t-vsv and plug it.
Otherwise, it will just keep bleeding air out of the actuator.

JekylandHyde · 03-29-2006, 08:06 AM

ST185 is correct.

The stock wastegate pressure is just over 7 psi.
The T-VSV bleeds air so you can run more boost than that.

NU2MR2 · 03-29-2006, 09:05 AM

Thanks, I didn't check that...The mbc is connected to the correct line, but I never even thought to look at the other one. I cant wait to ride in her again

! That test was the first time since last fall.

NU2MR2 · 03-30-2006, 03:25 PM

Well I got a chance to work on it today, and I fixed the overboosting problem...but I discovered a coolant leak on the line that runs to the oil cooler; so now I have to take it all apart again and fix that!

But after that I should be set!

ST185 · 03-31-2006, 06:32 AM

Ahh.... HFH have fun with that.

NU2MR2 · 03-31-2006, 09:02 AM

No kiddin...at least it's new parts, so it shouldn't be that bad.