Most people say you should be in the range of -18 to -20 on your boost gauge at idle. I have never seen this. Sometimes it will hit it but move back up to -12 to -10. I thought it could have been because of no FPR but even after putting an aftermarket one on, it has not changed anything. I dont know where to start in finding the leak.
Vacuume on boost gauge at idle - leak?
The_EE
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Most people say you should be in the range of -18 to -20 on your boost gauge at idle. I have never seen this. Sometimes it will hit it but move back up to -12 to -10. I thought it could have been because of no FPR but even after putting an aftermarket one on, it has not changed anything. I dont know where to start in finding the leak.
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Hows your compression? Low compression will give less vacuum.
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I would also be interested in the answer to this question as my car shows -14psi at idle and my idle rpm is real close to 750. I still need to check my base timing but my motor was just rebuilt with less than 5k on it
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Looks like its time for a rebuild,stock compression is 178, your motor is hurting...The_EE said:
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I have zero vacumm at idle, if i blip the throttle i only get -15 very shortly. Suppose i have a vacumm leak. Also, when coming to a stop my car likes to die, and it runs rich, but if i lean it out, it's extremely hesitant to move after i shift each gear. Do i have a problem, lol. Perhaps a vacumm leak. I removed all emissions and vacumm lines, i can't imagine that i did anything wrong, how can i test for vacumm leaks? Is reading zero at idle like super bad?
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Im in the same boat as you pal....
-10hg --> -12hg at idle, which thanks to some Biss screwing is now set at 680-750rpm, very low....
I am not too worried about it, unless someone can recognize this as a leak...Seeing as you idle like this too, I am not extremely worried, but when I looked at DJWIRED's boost gauge at 750rpm idle his was pinned at -15 just like he said; so Im not sure if this really is bad or not?
BTW, on startup if the motor is cold, I will idle at 1000-1500 rpm and my guage will be in the 15-18hg range, but like said before, it cruises down to ~11hg at my normal set idle
-10hg --> -12hg at idle, which thanks to some Biss screwing is now set at 680-750rpm, very low....
I am not too worried about it, unless someone can recognize this as a leak...Seeing as you idle like this too, I am not extremely worried, but when I looked at DJWIRED's boost gauge at 750rpm idle his was pinned at -15 just like he said; so Im not sure if this really is bad or not?
BTW, on startup if the motor is cold, I will idle at 1000-1500 rpm and my guage will be in the 15-18hg range, but like said before, it cruises down to ~11hg at my normal set idle
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I pull 12in/hg at Idle, because I have some big cams 
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The_EE said:
Not bad in my opinion. I ran my 11.89 with my motor @120-110-105-115 comp. You can still make good power although your poor vacuum is a reflection of those numbers. My gauge would hang around -12-14hg with those number above. My current motor is 150-150-145-145 and with 272s I have -10hg vacuum.
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Service limit is 122. You're still good
Take some soapy water, and spray it over the vaccuum lines and any other place where you could possibly have a leak (with it running) and see if you can't find the obvious leaks. I had the same problem this weekend.......I found i had a vaccuum leak around the #4 injector seal.
Take some soapy water, and spray it over the vaccuum lines and any other place where you could possibly have a leak (with it running) and see if you can't find the obvious leaks. I had the same problem this weekend.......I found i had a vaccuum leak around the #4 injector seal.
you guys with the low vacuum should also check to see if the connection to your boost gauge is secure. it can also be because you guys have a non-working boost gauge, so make sure you guys use a vacuum gun to accurately check the vacuum pressure and if it measures up to the boost gauge.
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Typically this is a sign of a boost leak. Especially at the injector seals, or the tb gaskets or the intake mani gasket. I would eliminate the easy things before really worrying if there is a problem.
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I do have a leak at the throttle body. I have yet to find out where it is. I got a couple big leaks out of the way. Ever since I have installed the boost gauge I have shown the same vac on the boost gauge. Its never changed. I dont think I have any leaks on the gauge itself though the gauge does show 1 pound with the car off and I have had the gauge only 6 months.greenstreak said:
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