Boost leak from biss scew [Merged 8-8]

[GeneralChaos]

Searched and cant find anything.

When I was performing my leakdown last time a ton of air was coming out of the BISS screw when I sprayed soapy water on it, as well as a part of the gasket.

Is this screw supposed to just unscrew out? or does the throttle body need to be taken apart? We couldnt get it out and I remember reading people replacing an o-ring in there somewhere.

Just trying to get all the materials and knowledge I need for this weekend.

 

[mra4886]

I know this is a big time newbie question, but i have been reading in other threads and reading about the BISS Screw, and i would like to know where the BISS Screw is located on the throttle body.

 

[billys90tsi]

top of the trottle body toward the front of the car cant miss it

 

[No_Skillz]

http://members.shaw.ca/dsm.1000q/Engineprimer/2G/throttlebody.htm

Circled in purple.

 

[steve]

http://members.shaw.ca/dsm.1000q/Engineprimer/1G/throttlebody.htm

In purple.

Steve



http://members.shaw.ca/dsm.1000q/Engineprimer/1G/biss.htm

in Red

 

[skinnykenny84]

that reminds me that my biss o-ring is leaking, , no really it is

 

[xveganxcowboyx]

that reminds me that my biss o-ring is leaking, , no really it is

Not an uncommon problem. $1 fix at the hardware store.

 

[MrBoxx]

Be careful when removing the screw. Recently, a member had to deal with the head of the screw stripping, making it impossible to either screw in or remove. Some cars have plastic ones, while it seems other cars have metal ones. Either way, be careful.

I just replaced my BISS and o-ring and was amazed at how flattened and shrunken the old o-ring was.

 

[mra4886]

Ok thank you all for the info and pics.

 

[VPrime]

Question... when replacing the screw and o ring, you can just take the screw right out right? Just turing the screw with out grounding it or what ever will have no effect correct? I wouldnt have to readjust the ide afterwards?

 

[steve]

Of course turning the screw has an effect, it changes the amount of air bypassing the throttle butterfly regardless of the terminals being grounded.

You will have to set the Base Idle Speed after changing the o-ring. I can never keep straight which 2G have the timing check connector or if their dataloggers will log ISC steps I can't describe the procedure.

What grounding the timing check and DLC mode pins do is cause the ECU to position the ISC to its default position so that you can adjust the BISS to get the engine to idle at the programmed speed. Once the connectors are ungrounded the ECU will move the ISC in and out to maintail that idle speed so another way of setting the BISS is by adjusting it until the ISC steps are right without ant pins grounded.

Steve

 

[Spoolio]

Well, I tested my system at 25psi, it gradually drops to 0 withing 15-20 seconds, which is not to bad i guess, but heres my problem, i have air comming from my biss screw and another unknown area around underneath my t/b area, anyone know of some common things i can start replacing.?

 

[srumel]

The leak at the BISS is likely just the o-ring that seals the head of the screw against the screw's bore.

The leak underneath the throttle body, if that is where it is coming from, is either going to be the gasket in between the lower and upper sections of the throttle body or the ISC gasket. This lower section is attached to the top piece with about 4-5 phillips-head screws, and the rubber gasket in between the two seals off the various chambers from one another. It could also be the ISC gasket. This, like the BISS, is an o-ring gasket but much larger.

 

[kmoore]

Like srumel said, the biss leak is just a o-ring. Replace it with a new one.

And also, the leak around the TB can be two things. Either A. TB gasket, like srumel said or B. Throttle body shaft seals. My guess would be B.

 

[Spoolio]

Eh at this point, I misewell replace all 3 anyways.

 

[super97gst]

Like srumel said, the biss leak is just a o-ring. Replace it with a new one.

And also, the leak around the TB can be two things. Either A. TB gasket, like srumel said or B. Throttle body shaft seals. My guess would be B.

Agreed.

C. EVAP system is bad about leaking as well. might check it out while your in there.

 

[Gooberlog]

Replace those seals and gaskets that may be causing you leak and then do another boost leak test and let us know what you found.

 

[daren_p]

Changing the shaft seals is abit of work. So if you want to verify if their the cause before hand, do a boost leak test like normal but when you listen to the leaks around the TB, move the throttle plate back & forth with your hand. If the pitch of the leaks change while doing this, the shafts seals are leaking & need to be replaced.

 

[magik95]

I searched the forum but really didnt find a ansewr. So my problem is my car runs fine but at boost I read 10psi briefly but no power.

I did a boost leak test and the biss screw is leaking like a pig! I went as far to remove all the ic pipes to check all connections and everything checks out good. No shaft play in my turbo, Im not hitting fuel cut as I see that came up alot in my search. I just have no power at boost.

I know the problem is in the tb/intake section. If it was'nt I wouldnt even read boost on the gauge right?

 

[silver bullit]

I searched the forum but really didnt find a ansewr. So my problem is my car runs fine but at boost I read 10psi briefly but no power.

I did a boost leak test and the biss screw is leaking like a pig! I went as far to remove all the ic pipes to check all connections and everything checks out good. No shaft play in my turbo, Im not hitting fuel cut as I see that came up alot in my search. I just have no power at boost.

I know the problem is in the tb/intake section. If it was'nt I wouldnt even read boost on the gauge right?

Where do you have the boost gauge taped into?

 

[magik95]

In the "p" nipple of the tb.

 

[silver bullit]

Do you still have the bcs hooked up and what gas you use?

Also check to see if the waste gate is sticking or stuck open

 

[magik95]

Im on 91 octane, I checked the wastegate even changed it out with a spare I had, and bcs is off I have a mbc.

 

[silver bullit]

Im on 91 octane, I checked the wastegate even changed it out with a spare I had, and bcs is off I have a mbc.

Electric or manual and how is it hooked up?

Have you tried a different boost source?

 

[magik95]

Its a manual. I have it hooked up like turbosmart instrucitons say the "t" piece between the waste gate and j-pipe nipple and the to the controll unit as per instructions. Hvent tried another boost source. Where I have it now has been working fine, minus this damn problem.

 

[BoostFrenzy]

Mmm, shiny new OEM parts to fix your leaks...mmmmm.

You can get yourself a new BISS screw set.