checking for vacumn leak around intake??
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TECH Junkie
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From: Key West, Florida
checking for vacumn leak around intake?? isn't there a way to check for gasket leaks and vaccum leaks around the intake manifold.
something like using a non-lite plumbers torch?
put my FAST intake on 2 weeks ago, ran great, sounded great, drove it 300miles home with no issues.
drove it one time since then and all was good.
drove it to work yesterday and when i went to leave, as i started the car, i immediatly noticed a low frequency, low volumn "sucking" sound.
i could hear it inside the car...over the TDs...and even more so under the hood.
this had to be something new since i would have notice it earlier, considering i worked on it and tuned it with the hood open for several hours after the install.
all i can think of is a vaccumn leak.
quickly checked the connection on the rear of the intake, but i need to check once it's cool.
tried to plug in my scanner and look at the fuel trims to see if they were out of whack but the scanner was not working
i'm NOT getting any SES lights and it drives strong.
suggestions?
something like using a non-lite plumbers torch?
put my FAST intake on 2 weeks ago, ran great, sounded great, drove it 300miles home with no issues.
drove it one time since then and all was good.
drove it to work yesterday and when i went to leave, as i started the car, i immediatly noticed a low frequency, low volumn "sucking" sound.
i could hear it inside the car...over the TDs...and even more so under the hood.
this had to be something new since i would have notice it earlier, considering i worked on it and tuned it with the hood open for several hours after the install.
all i can think of is a vaccumn leak.
quickly checked the connection on the rear of the intake, but i need to check once it's cool.
tried to plug in my scanner and look at the fuel trims to see if they were out of whack but the scanner was not working
i'm NOT getting any SES lights and it drives strong.
suggestions?
I have found vac leaks with the unlit tourch method. If the rpms srart to rise there's your leak. I have also read of people spraying carb cleaner around the intake and heads, again looking for a change in idleing rpms. Does fast give you new gaskest for the runners?
Thread Starter
TECH Junkie
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From: Key West, Florida
gaskets were pretty new, FAST was used, but not many miles.
seems odd that it occured after a long road trip in all kinds of traffic.
still need to investigate the hoses a little to make sure htey are all on.
seems odd that it occured after a long road trip in all kinds of traffic.
still need to investigate the hoses a little to make sure htey are all on.
Thread Starter
TECH Junkie
iTrader: (5)
Joined: Feb 2007
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From: Key West, Florida
kindda tried the torch method.
nothing really showed up.
i'm torn as to whether this sound was there all along...after the FAST install that is.
car seems to run great, and no SES.
its kindda like a vacumn cleaner sound, but really low pitch.
all hoses look fine, as does the stock bellows.
maybe i'll take it for some more spirited drivng and see how it reacts.
nothing really showed up.
i'm torn as to whether this sound was there all along...after the FAST install that is.
car seems to run great, and no SES.
its kindda like a vacumn cleaner sound, but really low pitch.
all hoses look fine, as does the stock bellows.
maybe i'll take it for some more spirited drivng and see how it reacts.
I had removed and reinstalled my ls6 intake 2 time before I put my blower on and First start up with the supercharger it idled like ****, the ses light was on and the moter was rough when hitting the gas pedal in neutral. When I waved the tourch around the intake the rpms jumped right up. Replaced the intake manifold gaskets and and the engine sounded so much differant. So you may just have a hose that came off or something little if the car is idleing fine and you can drive it. Did you change any thing with you pcv system? Maybe check those hoses on the rocker covers.
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Thread Starter
TECH Junkie
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From: Key West, Florida
didn't change any of the PVC.
i actually found a hose connector that had a hole in it when i did the install. but i put a new one on.
checked pretty thuroughly today...didn't feel any issue with the hoses.
for the hell of it i pulled the hose off the mouth of the manifold (passenger side) and the car immediatly idled funny.
went back to normal when i put it back on.
something very possible....
its my imagination
i actually found a hose connector that had a hole in it when i did the install. but i put a new one on.
checked pretty thuroughly today...didn't feel any issue with the hoses.
for the hell of it i pulled the hose off the mouth of the manifold (passenger side) and the car immediatly idled funny.
went back to normal when i put it back on.
something very possible....
its my imagination
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TECH Junkie
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Joined: Feb 2007
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From: Key West, Florida
not my imagination...my wife could hear it...and said she didn't remember it from before. she was with me the entire 300+ mile drive back from the tuner.
SOOOO....
i tried pulling the belts off...still made the sound, so its not a pulley.
i pulled the plug on the Mez EWP and that didn't do anything either.
gonna try starter fluid tomorrow since the torch trick didn't work.
SOOOO....
i tried pulling the belts off...still made the sound, so its not a pulley.
i pulled the plug on the Mez EWP and that didn't do anything either.
gonna try starter fluid tomorrow since the torch trick didn't work.
borrow or buy a stethoscope and narrow down the location, did you try wiggling the fuel injectors and seeing if the sound changed, there not in very tight. Also I'm thinking it might be something around the air filter assembly/housing. It shouldn't be to hard to find if it's that loud.
If it's that loud and it doesn't have any drivability issues I'm thinking it might be in PCV system, like it's disconnect somewhere, try clamping the hose at the throttle body and seeing if the sound goes away. You ever pull a PCV valve out of a valve cover? Is it that loud?
If it's that loud and it doesn't have any drivability issues I'm thinking it might be in PCV system, like it's disconnect somewhere, try clamping the hose at the throttle body and seeing if the sound goes away. You ever pull a PCV valve out of a valve cover? Is it that loud?
Thread Starter
TECH Junkie
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Joined: Feb 2007
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From: Key West, Florida
yeah you would think it would be easy to pinpoint. but with the engine and exhaust being so loud it makes it hard.
i'll pull the lid and maf part apart tomorrow and check them out.
i checked the PVC on the driver side since had that out to get the brake booster line out easier when i did the intake.
i'll try pulling the hose and plugging it.
i need to pull the hose on the lower passenger side of the intake mouth correct? and plug the connection on the intake. that eliminates the PVC system basically....CORRECT?
i'll pull the lid and maf part apart tomorrow and check them out.
i checked the PVC on the driver side since had that out to get the brake booster line out easier when i did the intake.
i'll try pulling the hose and plugging it.
i need to pull the hose on the lower passenger side of the intake mouth correct? and plug the connection on the intake. that eliminates the PVC system basically....CORRECT?
yeah you would think it would be easy to pinpoint. but with the engine and exhaust being so loud it makes it hard.
i'll pull the lid and maf part apart tomorrow and check them out.
i checked the PVC on the driver side since had that out to get the brake booster line out easier when i did the intake.
i'll try pulling the hose and plugging it.
i need to pull the hose on the lower passenger side of the intake mouth correct? and plug the connection on the intake. that eliminates the PVC system basically....CORRECT?
i'll pull the lid and maf part apart tomorrow and check them out.
i checked the PVC on the driver side since had that out to get the brake booster line out easier when i did the intake.
i'll try pulling the hose and plugging it.
i need to pull the hose on the lower passenger side of the intake mouth correct? and plug the connection on the intake. that eliminates the PVC system basically....CORRECT?
I'll ask a dumb question but it's worth considering. Is it the A.I.R. pump, is it even still on the car? Considering all of your mods I'm assuming, no.
I chased a vacuum leak that sounded the same on my LT1 after a RR change. Never could find it with carb cleaner or ether. I ended up coating a several the of vacuum lines with silicone until I found the bad one. Then I went back and replaced everything I smeared silicone on. lol
They are a pain to chase down. Good luck!
I chased a vacuum leak that sounded the same on my LT1 after a RR change. Never could find it with carb cleaner or ether. I ended up coating a several the of vacuum lines with silicone until I found the bad one. Then I went back and replaced everything I smeared silicone on. lol
They are a pain to chase down. Good luck!
Thread Starter
TECH Junkie
iTrader: (5)
Joined: Feb 2007
Posts: 3,183
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From: Key West, Florida
well i double checked the hoses, turns out the hose on the passenger side was disconnected.
BUT...
connecting it did nothing for the noise.
and pulling the PVC off the front of the manifold and plugging that did not change the noise.
so its not the pvc.
knew it couldn't be that easy.
BUT...
connecting it did nothing for the noise.
and pulling the PVC off the front of the manifold and plugging that did not change the noise.
so its not the pvc.
knew it couldn't be that easy.
