i have an obvious vacuum leak. i installed a boost/vac gauge today and have barely any vac. the gauge reads 0-1 on vac side. the tube that i tapped was the pressure tube to the right of the throttle body. (not the fuel pressure). the gauge works when you blow into the tube. i pulled that same tube while running & no air was forced out of it. does anyone have any suggestions/links that they could notify me of? any help would be greatly appreciated. the gauge is reading boost, is it common for the gauge to read boost & not vacuum when a leak is present? i am not having any idle problems with the car. if there is no vacuum due to a leak, wouldn't it affect the idle? as you can tell, this is my first time installing a mbc & boost gauge. i need some help. thanks
vacuum leak??? help...
stangabishi
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i have an obvious vacuum leak. i installed a boost/vac gauge today and have barely any vac. the gauge reads 0-1 on vac side. the tube that i tapped was the pressure tube to the right of the throttle body. (not the fuel pressure). the gauge works when you blow into the tube. i pulled that same tube while running & no air was forced out of it. does anyone have any suggestions/links that they could notify me of? any help would be greatly appreciated. the gauge is reading boost, is it common for the gauge to read boost & not vacuum when a leak is present? i am not having any idle problems with the car. if there is no vacuum due to a leak, wouldn't it affect the idle? as you can tell, this is my first time installing a mbc & boost gauge. i need some help. thanks
Which port did you put it on? What brand / type / style of gauge is it? You could hook it up to a vacuum pump to make sure it's reading vacuum correctly.
Try connecting it to the FPR solenoid line (the one coming from the intake manifold - not the one going to the regulator). I believe the "P" port on the TB will work as well.
There's absolutely no way that the car would idle if you're only getting 1 inch of vacuum.
Try connecting it to the FPR solenoid line (the one coming from the intake manifold - not the one going to the regulator). I believe the "P" port on the TB will work as well.
There's absolutely no way that the car would idle if you're only getting 1 inch of vacuum.
Agree
Michael's right, with only 1 inch of mercury on your gauge the car wouldn't idle at all. If you have the gauge hooked up to the "P" hose on the TB, you should see a vacuum reading. That's where mine is. Other ports may act like a check valve and conduct boost but not vacuum (will be closed at vac. and open at boost, allowing air to flow one way only), which may be why you felt no air from the port while the engine was idling. Try tapping the gauge line to other boost/vacuum sources like the FPR pressure line at the manifold, then other known sources of vacuum. If you get the same results, the gauge may not be good. If the engine is getting any less than say 15 or 14 inches of vacuum, the idle would be very erratic, to say nothing of 1 inch. That's basically full throttle without boost...or OFF, however you're thinking of it.
I don't know if this is the best way to do it, but I also hooked my boost controller to the same line my gauge is on, so (for all intents and purposes) my gauge is seeing the same pressure that my controller is seeing. I guess it's that engineer's congruency thing that always seems to get to me (sometimes I hate being an engineering nerd!).
Correct me if I'm wrong guys...I'm always learning too.
Michael's right, with only 1 inch of mercury on your gauge the car wouldn't idle at all. If you have the gauge hooked up to the "P" hose on the TB, you should see a vacuum reading. That's where mine is. Other ports may act like a check valve and conduct boost but not vacuum (will be closed at vac. and open at boost, allowing air to flow one way only), which may be why you felt no air from the port while the engine was idling. Try tapping the gauge line to other boost/vacuum sources like the FPR pressure line at the manifold, then other known sources of vacuum. If you get the same results, the gauge may not be good. If the engine is getting any less than say 15 or 14 inches of vacuum, the idle would be very erratic, to say nothing of 1 inch. That's basically full throttle without boost...or OFF, however you're thinking of it.
I don't know if this is the best way to do it, but I also hooked my boost controller to the same line my gauge is on, so (for all intents and purposes) my gauge is seeing the same pressure that my controller is seeing. I guess it's that engineer's congruency thing that always seems to get to me (sometimes I hate being an engineering nerd!).
Correct me if I'm wrong guys...I'm always learning too.
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See my response in your original post
http://www.dsmtalk.com/forums/showthread.php?threadid=29706
I don't know why the thread is showing as 0 replies....
http://www.dsmtalk.com/forums/showthread.php?threadid=29706
I don't know why the thread is showing as 0 replies....
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408 Posts
the gauge is fine, i tested it. thanks for your help guys. i think that i originally had it tapped in the wrong place. i will definitely check & re-install. thank you for your help & links.
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