I've got my 27/6, tial 38 in dual port controlled by a mbc, yet even with the mbc turned all the way down and my crossover still leaking a small amount I can't get the boost below 15-16psi. Which is not much fun on the stock computers.

Well, more specific, most of the time the boost doesn't go above 12-13psi, but doing some straight shot freeway onramp runs recently have got it going to 15-16 and then the computer cutting power.

Could I have done something incorrect with the vacuum lines? They are still all connected, so the question would be if having them routed incorrectly could affect the wastegate control. But most of the time, or at least until recently, the boost had been staying pretty docile at 13psi or so.


I'll poke around at the wastegate and whatnot when I'm in there doing the clutch/brake lines again later this week, but any suggestions for what I should be looking for?

 

Most Tials come with the .8 bar spring (12 +/- psi) and that will be the absolute minimum boost setting you will get. Any significant leak in the vacuum/boost line to the wastegate would cause the boost setting to increase.
I would look for a leak or a kink in the line. Obstructions will do the same thing. You could undo the lines (both ends) and blow through them – there should not be any restriction if the boost controller is set to min.

 

So how is that K27/6 working for you? I heard it came from an awesome 951. You still dont want the MAX951 chip I had for that turbo?

 

Ok, thanks for the info chris. I looked at all the lines and none of them had any kinks or anything. They were all brand new lindsey silicon vacuum lines that only have about 500mi on them now. The only thing I can think of getting into the lines would be some of the white plumbing tape I used on the connections of the mbc, but I'm pretty sure I didn't allow any of the tape to get past the threads into the air passage.

If the banjo bolts on the tial were to have backed out enough from vibration to cause there to be an air leak, could that cause the issue? Don't the wastegates basically stay closed without the vacuum? I'll check those later today.


Come to think of it, I haven't really heard the usual exhaust type noises lately...
Really? I heard the car it came out kept breaking down or something....

Turbo is working great. No burning oil or anything. I should be getting my maxtronic finally installed later today, so I'll report back.

 

"How do I decrease boost?"

???????????????

I think that is the first time someone has asked that in here. LOL

 

The boost controllers work by modulating the boost signal to the wastegate. Any leak or obstruction in the signal line will result in the wastegate diaphragm seeing less pressure and therefore allowing to stay closed longer (and allowing higher boost).
So a leak anywhere in the control system will increase the boost

 

Yeah...........what a wuss..........

 

Isn't it possible your tial has the 1.0 bar spring. Then the minimum boost is around 15 Psi?

 

Put a foreign object in the jboot.

 

I suppose so, but when I first started driving the car after I put it all back together I was only doing 12psi, so there must be an air leak somewhere.



If I weren't running stock chips, I wouldn't be complaining about more boost. It is just getting annoying because I keep having the computer cut power.

 

I suppose so, but when I first started driving the car after I put it all back together I was only doing 12psi, so there must be an air leak somewhere.



If I weren't running stock chips, I wouldn't be complaining about more boost. It is just getting annoying because I keep having the computer cut power.

Huh?

 

Even if the boost on an MBC is adjusted to minimum there normally is a small pressure drop across it. So you should be able to lower the pressure maybe a couple of psi if you substitute the MBC with a tube.

If there is an ever increasing air leak then it will only be a matter of time before you are in the same situation again.

Laust

 

Good point Laust - your post just reminded me of how I had sort of hobbled together a vacuum line piece to connect the silicon lindsey lines to the stock metal control line setup. I also had been disconnecting the banjo on the hard pipe a lot when I was messing around with the coolant gooseneck, so it could be at that end too. I'll go through the whole line and see if anything is disconnected.

 

if that doesnt work can you get a WG softer spring ? completely disconnect the boost controller maybe..

 

Ok, simple problem. The hose I had reused from some part of the vacuum system when putting the car back together between the banjo on the hardpipe and the metal control line had torn across the bottom half (came apart in pieces when I tried pulling it off). Stuck a different hose from my vacuum line box on there so as long as this hose doesn't fall apart all should be good.