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Discussion Starter · #1 ·
What up guys?

Here's the deal, I have been having boost issues with my 94 TT lately. I have low boost regardless of the gear it's in. i have done a boost leak test and there are none. I checked my vsv's and they checked out.

So I decided to run my wastegate with the hose pulled. It only ran ~13 psi and the boost would sometimes drop. So the next step I took was to see if the wastgate arm would move when I applied air pressure to it, sure enough the arm moved. I noticed when I was applying air pressure to the hose I could hear the air escaping the wastegate. Is that normal or is my diaphragm torn? what else could be the problem. Thanks guys.
 

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Wastegate spring could be worn out. There is a WG spring mod that most people do from MKIV.com "tech articles" this helped on mine. I would try this first then think about replacing it.
 

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Montreal_TT said:
I will try that. ^^^

When applying air pressure to the nipple on the top of the wastegate, is the air supposed to travel through to the nipple on the side of the wastegate?

Yes, it is supposed to pass through.

You could also trying wiring the arm open. If you do this and boost goes up, then that's your problem. But be carefull that you don't overboost or detonate, i.e. no long highway pulls.
 

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Discussion Starter · #7 ·
I just ran the spring mod and no luck. Still only boosting ~13 psi. but now I noticed in the lower gears (1,2,3) I would make it to ~12-13 psi and then pressure would fall to 8 psi, once I shift to 4 th, 5 th and 6th the boost will hold steady at 13 psi.

I am so lost right now any help will be greatly appreciated.
 

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Process of elimination, I think the next step would be to replace the WG & see if it still does it. If not, problem solved. If it does, keep trying to find the problem. GL
 

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Discussion Starter · #13 ·
I found the culprit, it's the pressure tank. I had put it into temp TTC to eliminate some possibilities, then I took it out for a test run with no Luck. Went back home, to the machine shop, and checked the vaccum hoses for pressure, there was none. so I manually pressurized the lines to keep the actuators open. Took it for another test run and voila problem solved. also tried running open wastegate, that shit is fun at 19 psi.

now I will call Curt to order a new Tank

thanks guys for all the help
 

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Glad you found it...enjoy full boost
 
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