Need Some Vacuum Help

**gtpeddie** · 09-11-2012

So apparently i have a vacuum leak my boost gauge is reading only 11 vac. It has been like this for a while now, it hasn't effected my MPG's enough for me to notice atleast. My long term fuel trim reads only 16.4 at its highest on my aeroforce. I tried spraying carb cleaner around and had no luck, no cracked vac lines, and i dont hear anything. No check engine lights are on or anything. The only thing I could think of is because of the bad LIM gasket, could this be causing this? I know for sure my LIM gasket is bad and needs to be replaced, I was trying to hold out on changing it until I finished my engine build but thats not happening anytime soon. So either way im gonna change it. Do you think that could be it? Im not to sure on this one, after I change the LIM gasket im gonna put new vacuum lines on and see what happens. I know average vacuum is around 17-18 or so.

**BillBoost37** · 09-12-2012

Stop blaming the LIM gasket.

Take the center hose off the vacuum manifold on top of the charger plug it and what do you get? (BTW a friends finger works well for these tests)
Take the brake booster hose out of the booster and plug it with a thumb, what do you get?

For this large of a leak.. that is... IF YOU ARE READING inhg AND NOT lbs... you should be able to find it wtih a can of carb cleaner. You have a huge gaping leak. I suspect your gauge is reading pounds though..which means it's fine and you need to find the leak that is likely your EGR tube or something silly.

**gtpeddie** · 09-12-2012

Thanks Bill, Ill have to give it a try. I did try and check for it with carb cleaner but had no luck. I also had another vacuum gauge hooked up to the vac line by the fuel rails and it read the same as the gauge (this is the second boost gauge I had in my car both read the same). Also I am reading it in "inhg"

**blueguy** · 09-12-2012

Do you still have the EGR?

Most of the time running seafoam will expose a vacuum leak if you run it through all the mechanical systems...yay smoke.

Or, you have a '97, I can't remember if I asked you this when you PM'd me but is the TB stock? Ported? Is it of a '97or '98 style or a '99+ by chance?

Because I know when I had a ported TB on my L36 car I couldn't find the vacuum leak for the life of me either, until we re-tuned it. Took care of that like a boss.

**gtpeddie** · 09-12-2012

Originally Posted by blueguy91

Do you still have the EGR?

Most of the time running seafoam will expose a vacuum leak if you run it through all the mechanical systems...yay smoke.

Or, you have a '97, I can't remember if I asked you this when you PM'd me but is the TB stock? Ported? Is it of a '97or '98 style or a '99+ by chance?

Because I know when I had a ported TB on my L36 car I couldn't find the vacuum leak for the life of me either, until we re-tuned it. Took care of that like a boss.

im still running the EGR yas, i plan on deleting it when i put my headers on. my TB is also a stock 97 TB not ported or anything. i might try and run some sea foam through it see if that helps. my friend also has a tuner so i want to see if he can hook me up. i been looking for the vac leak but havent found nothing yet and i dont hear anything.