Weird issue with boosting.

[my98GST]

Mods: td06h 20g turbo, FMIC with short route, 1g but switched to type-s bov, Injen intake, 3" turbo back, 255lph, fpr, 550's, safcII.

I had a Turboxs MBC on it and I had it turned up quite a bit. I took it out for a good drive one day and noticed that I could only make 15lbs no matter how much I backed the screw out. I had it hooked up using the compressor house nipple and the wastegate. I blocked off the stock BCS and intake ports. I then took the MBC off and returned back to stock BCS and it will only make 13lbs.

I then did a boost leak test and I noticed that my bov flange was ever so slightly leaking so I fixed it. I then noticed tremendous air hissing coming from the TB. I then sprayed windex on the tb all over and there was no bubbles coming from anywhere. What the heck? The only place that I could see air coming out was the BISS screw. I'm going to replace it. Is there anywhere else that I should check on the TB for leaks? Also what else could I check?

 

[somdturbo]

There is a tb shaft seal that leaks commonly as well. There used to be a write up on vfaq on how to replace it. If you have checked and sealed everything else this would be a good thing to check out. good luck

 

[travislaw]

There is a tb shaft seal that leaks commonly as well. There used to be a write up on vfaq on how to replace it. If you have checked and sealed everything else this would be a good thing to check out. good luck

http://www.ca.dsm.org/faq/tb-shaftseals.html
or
http://www.plymouthlaser.com/tbor.htm

For the parts:

http://www.machv.com/throtbodseal.html

I just did this with my car. It was really easy to do as long as you follow the directions. The kit from MachV replaces the metal parts you will pull out of the throttle shaft area.

 

[my98GST]

damn i just looked at the vfaq on it and it looks like a PITA!!! Did it fix your boosting problems?

 

[travislaw]

damn i just looked at the vfaq on it and it looks like a PITA!!! Did it fix your boosting problems?

I haven't reinstalled it yet. I am doing it this afternoon. I had a spare throttle lying around that I replaced all the O-ring seals on. Here are the steps I took, the biggest thing to remember is when the Vfaq directions tell you to mark something a certain way, do it.

1. Remove Throttle
2. Remove sensors
3. Remove two screws on throttle plate
4. Remove Thorttle plate
5. Remove nut on side with the TPS sensor
6. Take the part out and remember which way it went in
7. Take the nut off the side with the spring
8. Use white out to make a line down spring to get same tension back
9. Remove throttle cable holder, plastic tab and both springs
10. Take Shaft out
11. Remove the two metal o-ring holders
12. Clean out all of the old O ring
13. If you get the MachV O ring set you can skip the step of cleaning out the O-ring holders because you won't be using them anymore.
14. Slide shaft back in.
15. Reinstall Plate in correct direction and put both screws back in.
16. Reinstall the springs and all those parts that go with it, remember to wind the spring to its original tension "when your white out line markins line up again you know you have it
17. Reinstall parts on TPS side
18. Put Senesor Back In
19. Reinstall back in car

The hardest part was the springs so far. Like I said I haven't installed the throttle yet.

 

[dub2gsx]

If you are still on the stock 2g tb then you might want to look into this:
http://cgi.ebay.com/ebaymotors/60mm-Throttle-Body-2G-DSM-Eclipse-Talon_W0QQcmdZViewItemQQcategoryZ33558QQitemZ8058030652QQrdZ1QQsspagenameZWDVW

It has the half shaft mod the doesn't leak and if you send him your core he will refund some money!

Brian

 

[my98GST]

Anyone else got some ideas that may be causing this also?

 

[GVR4592]

Fix the biss screw, then retest it. If it still leaks then you should be able to tell if it's coming from the tb shaft seals. Try rotating the tb while testing.