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Discussion Starter #1
I just helped a buddy install some BPU parts onto his stock 1997 Automatic Supra TT. We installed the following parts:

eBay Downpipe
Tanaba Exhaust
"Max Air" Intake Kit
HorsepowerFreaks FMIC Kit
Tial 50mm BOV
NGK 6097 Spark Plugs
Greddy BCC to 4.1 volts
Manual Boost Controller

Also purchased but not yet installed are a set of Cam Gears and SAFC2.

Here is my dilema. We welded the BOV to the IC piping on the driver side (throttle body side) and left the stock BOV in place. We tee'd the Tial off into a vacuum line I found on the intake manifold that was on the left side and about 3/4 of the way back. We left the stock BOV untouched. This setup caused the car to not even want to start and when it did it would die as soon as he revved and let off the gas. So I capped off the Tial and the vacuum line that was going to the Tail, so that it would use only the stock BOV again, and it works perfect. So obviously the Tial is the cause and I actually expected that it may cause a problem after seeing posts on here, especially with an 'Automatic', but how can I fix this. Is there ANYTHING I can do to make it work. Does the SAFC2 have anything to fix this by chance? Was my vacuum source maybe not a good one? Should I remove the OEM BOV and use the vacuum source it was using? PLEASE HELP ME MAKE THIS THING WORK....lol....my buddy is all upset that his BOV aint working right now, but loves the new found power! Thanks in advance for any help! Peace!
 

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Silent
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Don't get an AFC.

Your problems are common, but more pronounced than normal.

Look around for vacuum or boost leaks.

If that doesnt work, a VPC or MAP ecu or whatever you piggy-backers are hooked on these days. Basically a conversion to a speed-density setup will solve your problem with a solution instead of band-aids.

Especially with an auto, i would skip the cam gear (until you're really making big power its not gonna helpt hat much. Any power it gains you at peak, its robbing from you at lower rpms). The money saved combined saving with a s-afc, you could really get a vpc.
 

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Silent
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It may also not be possible, but if you have any way of testing the bov. It may be sticking open on blowoff. That would certainly not help things.
 

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Discussion Starter #4
Thanks for the reply! I was hoping to not have to involve the VPC right now. He already has the cam gears and the AFC2. Any other possible solutions /band-aids for now? If there were any leaks, wouldnt it run like crap with the stock BOV too? The Tial is brand new, and I suppose it could possibly be bad, but I wouldnt think so. Thanks again!
 

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Silent
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I am not extremely familiar with tial valves, but i'm going to assume they have some sort of adjusting nut. The blits and hks valves I have both do. You need to tighten it up one way or another. Theres the adjusting nut, but i believe with the tial ones you can also buy a spring with a different spring rate. I just saw a thread on that and if you search you should be able to find where to get a new spring pretty easily.

It is also possible that you have quite a few (or one bad one) leaks and the stock BOV could be just recirculating enough not to stall on letoff of gas. It is common for people who don't actively mod their cars to have lotsa cracks or popped small hoses. Especially near the back of the throttle body-area. Check that out first.
 

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Discussion Starter #6
Is there any special process for pressure testing the Supra. I am used to just making an endcap with a compressor fitting on it that can be clamped via coupler to the turbo inlet. Then just hook up the compressor line to it to supply some pressure to it. Then with a spray bottle and soapy water, check for leaks. Would this method work ok?

Oh, and I dont think the Tial has any adjustment nuts or anything like that, just the ability to change out springs, but I do not understand how the spring pressure on a BOV works exactly. If it is a 7psi spring. it shouldnt open to atmosphere until 7psi correct, which is not possible at idle??? Thanks again!
 

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Hokiesup said:
Especially with an auto, i would skip the cam gear (until you're really making big power its not gonna helpt hat much. Any power it gains you at peak, its robbing from you at lower rpms). The money saved combined saving with a s-afc, you could really get a vpc.

Bad advice. A cam gear is proven to gain 10hp across the curve at simple BPU levels, time after time. The cost is a little over $100. You'll be lucky to make the same gains with a VPC and it will cost you $500-600.

As for the original question. I think you've answered it yourself. Just leave the stock BOV on.
 

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Silent
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We are starting to get outside the realm of my experience here, I haven't had a BOV go bad on me yet, but if i understand it correctly, the springs are rated by stiffness, but not pressure like a wastegate spring is. If your BOV was only opening under 7psi of boost or more you'd have other troubles. If they make a stiffer spring, it would be less likely to open under low load, stalling the car. Thats where i'd start if he's set on keeping the BOV and not moving speed-density.

And as for the cam gear, if you have it go for it. I may have been out of the game for a while while the car was down, but I remember the jury being out on them. If they are somehow giving powerband-wide increases now, I'll be the next one to get one. Its just my understanding of how a cam system works is that its ALWAYS give and take or optimization, not free power increases across the board.
 
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