Boost leak on back of TB, can't fix? Help

[turbotsi92]

I did a boost leak test today because my car hasn't been running right. I found a leak on the fire wall side of the throttle body. I put a new gasket on it, still the same thing, I even took the bolts a few lbs over the specs, and still a leak, is there anything besides the gasket on that side that could be leaking boost? Also, when my car is sitting there idling it will idle constant, then drop of really quick and back to normal, does this have anything to do with it? I have been reading some post and alot seems like it could be my ISC because my car idles really low and sometimes stalls when I come to a stop or my plugs and wires would be my other conclusion. My plugs are pretty new though, and my wires are about 2 years old( Is this to old)?

 

[DevilSperm]

theres a good chance your shaft seals are leaking and thats what you are hearing http://store.yahoo.com/machv/throtbodseal.html
easy fix http://www.plymouthlaser.com/tbor.htm and http://www.ca.dsm.org/faq/tb-shaftseals.html

your idle surge sounds like it could be the ISC http://www.crebotech.com/page2.html , however, sometimes its just the BISS needing an adjustment. http://vfaq.com/mods/BISS-1G.html

 

[oldman]

Turn the throttle plate, if hissing changes then it's definitely the shaft seals. You should spray soapy water on injector seals, IM gasket, BISS crew, vacuum hoses...on the next test so you don't keep taking off the TB. What is your vacuum reading?

 

[turbotsi92]

I spayed down everything with soapy water, didn't see any bubbles, but I can hear the air leaking out on the back side, and if I put my finger back there I can muffle the sound so I know about where it is. It really feels like the gasket area, but the shaft seal is not far away. It is hard to see back there to see if there is any bubbles.

 

[turbotsi92]

Vacuum is at 17-19

 

[oldman]

The only thing I can think of which will leak on the firewall side of the TB is shaft seals, rotate the throttle plate like I posted on your next test.

 

[GST with PSI]

how about nicks or an untrue gasket surface? these could cause leakage no matter how new you shaft seals are. check the gasket surface with a strait edge. if there are some improfections (groves, scratches) you may be able to fix them with some kind of sealer.

 

[Spaniel1287]

Yea my TB is leaking also. My talon is automatic and if i hold the pedal not quite all the way down but most of the way, i can get the boost up to abotu 11 or 12 psi and it will just stick there meaning no leaks. Well if i go WOT it will spike up to 15psi only for a second and then it will drop back to 12-13psi. Also after doing a leak test my TB is leakin around that big screw in the back of the TB. I need to get around to fixin that sometime.

 

[oldman]

My talon is automatic and if i hold the pedal not quite all the way down but most of the way, i can get the boost up to abotu 11 or 12 psi and it will just stick there meaning no leaks.

Just because you're holding boost doesn't mean you're not leaking, it just means the turbo is working harder to maintain that level.

Well if i go WOT it will spike up to 15psi only for a second and then it will drop back to 12-13psi.

I'm not saying you have no leaks because you probably do but T25 is known for spiking and dropping off at higher rpms.

 

[blcknspo0ln]

I've been battling the same problem for quite a while now. I STILL idle at -16 vac

- if you have the TB off again, use some RTV sealant on there.
- Do the shaft seals
- Obviously another set of gaskets
- New biss screw
- Make sure the O-ring is on your ISC
- Check FIAV

and last, but not least (The last step on my quest) Is to replace the IM gasket. It's a PITA to do and perhaps that's why I've been lagging on it for so long.

 

[oldman]

and last, but not least (The last step on my quest) Is to replace the IM gasket. It's a PITA to do and perhaps that's why I've been lagging on it for so long.

1. Get yourself the shortest 12mm geared wrench (don't know if that's the correct term) you can find, I have one specifically for that purpose if you want to borrow.

2. Unbolt your DP, it's easier from the bottom up.

 

[blcknspo0ln]

interesting enough, I remember reading somewhere angle socket's with a long extension work best. I'll have a looksee when I get home from work.

thanks