anybody know if there is any type of "air" related hose that is on the passenger side under the backseat area (under the car)? I hear a hissing sound around that area but cannot see anything that resembles piping/tubing. The area is just ahead of the passenger side rear wheel close to the endge of the car.

my idle sometimes dip below zero when decelerating so i assume there is a leak. the only area where i can hear anything that resemble a leak is that area, but cannot seem to locate tubing/piping. do you think cleaning up the throttle body will do any good? if so what should i use?


thanks in advance

 

What year is your car? That will likely help someone narrow down the possibilities. I know precious little regarding FI cars but knowing the year will help those who do. Good luck

 

Check your vacum hose.

-Sean

 

is there any "sure" way of checking for leaks?
have anybody tried using throttle body cleaners that blow out black smoke...or something like that?

thanks

 

you have a leak somewhere...

 

normally when you idle dips below zero.the engine will stall! a " air" leak will not cause you to stall out, it may be a firing issue ( timing, ignition,sensor) can your hissing be a exhaust leak?

 

don't think it's an exhaust leak. checked already. i guess i'll just live with it for a few more months. I'm planning on getting bigger injectors and the APS 3' exhaust. When that time comes, i'll have everything re-tuned and look at. thanks for all the responses

 

since you have an APS TT vehicle... did you check the vacuum hose to the fuel pressure regulator? there is a vacuum hose that connects to the fuel pressure regulator (attached to the fuel pump, located under the passenger rear seat) which may have popped off, leaving you that hiss... that could be a start.

http://www.airpowersystems.com.au/35...m#_Toc86034197
look at #38~40.

diagrams for reference:
http://www.airpowersystems.com.au/35...uel%20Pump.pdf
http://www.airpowersystems.com.au/35...m%20routes.pdf

 

Not sure if they do this with TT's, would not really make sence too. But when I had my NOS installed they put in a colder plug, to prevent prefiring. If I am sitting in traffic it sometimes may stall out.

 

thank you very much. this may be the issue. i do hear a hiss around that area. you may have just saved me from my urge to uprgade cause when things break you upgrade . then you look at your wallet and pout LOL

 

i do have one step colder but i don't thing it can cause the engine to stall out. Mine idles fine, it just stalls when shifting to neutral while coming to a stop.

thanks for the response

 

crank the car and remove the rear seat... just pull on the seats upward. they're secured by clips and is very easy to take off. you'll see the fuel pump assembly cover. if the hiss is directly from that area, then there is your problem.

do you have a boost gauge or anything? did you feel any power loss when driving?

 

yes i have a boost gauge. i don't really noticed the power loss (haven't really had a chance to really step on it). but the boost gauge shows that i haven't loss boost. converting from psi to kg/cm2: i'm still boosting at roughly .4 ~6.5psi. can't really tell exactly because it's hard to accurately read the analogue greddy gauge while driving.

will the leak in the fuel pressure regulator affect boost dramitically?

i'm still at work so have not had the chance to remove the rear seat. i will do that first thing when i get a chance.

thanks for all the help

 

well i poped up the back seat and low-n-behold the hiss is there. the only problem now is to find it. looked at all the hose that i can access (which are fuel lines) and cannot find the source of the hiss. it is most likely the vacum line but it is behind the regulator.

i'll try to study the diagram that panda007 provided and see what i can do. may need to remove the regulator in order to reach that hose.

 

has anybody had any experience removing the fuel regulator? any cautions such as the fuel hoses?

thanks