Hunting down a vacuum leak.
02-12-2013, 06:41 PM
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Hunting down a vacuum leak. Hey everyone, I just redid my entire pcv line system after finding a hole in the line behind the intake manifold. Before my idle would jump randomly from 785(where it's supposed to be) up to 1300(not where it's supposed to be).
After fixing the pcv lines it idles a bit better, I use my hptuners software to check IAC readings, and they still stay around 0-10 at idle. The car is cammed by the way. Idle jumps from 785-900. And sometimes hovers around 1000 still.
My question is where else could there be a vacuum leak? Should I take the intake manifold off and change the gaskets? As well as check the booster line behind the manifold? If it helps I have an M6 and when cruising and putting the car in neutral the idle never drops to normal until I'm at a complete stop. Tb volt's at .47.
After fixing the pcv lines it idles a bit better, I use my hptuners software to check IAC readings, and they still stay around 0-10 at idle. The car is cammed by the way. Idle jumps from 785-900. And sometimes hovers around 1000 still.
My question is where else could there be a vacuum leak? Should I take the intake manifold off and change the gaskets? As well as check the booster line behind the manifold? If it helps I have an M6 and when cruising and putting the car in neutral the idle never drops to normal until I'm at a complete stop. Tb volt's at .47.
02-12-2013, 07:12 PM
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Theirs a particular spray to use to indicate where vacuum leaks are. I was their when my shop used it. Sprayed a very fine like mist/powder over the engine bay and whatched it get sucked into a pin sized hole right by my pcv valve. I just can't remember what it was called.
02-12-2013, 07:58 PM
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I know it's sealed near the pcv valve, it will be hard to see spraying it behind the intake near the MAP since these engines are stuffed so far back. Only bad thing is I will have to take the intake off to be able to get to the maP without breaking anything.
So I guess after changing intake/tb gaskets, as well as checking the MAP and booster line. If there is still a vacuum leak, where would I check next? Only possible things could be the booster itself, or maybe the tps and IAC valve right?
So I guess after changing intake/tb gaskets, as well as checking the MAP and booster line. If there is still a vacuum leak, where would I check next? Only possible things could be the booster itself, or maybe the tps and IAC valve right?
02-12-2013, 09:44 PM
#4
I used a small propane cylinder. Remove the portion of the nozzle with the air holes. Then, place a piece of rubber hose over the cylinder nozzle.
Open the gas & run the hose end around the manifold, TB, maf, booster line, etc.
If you hear a change in the idle, you've found a potential leak.
About the IAC reading...are you able to adjust the TB to get the IAC within specs? I believe it should fall between 40 & 60 counts.
Open the gas & run the hose end around the manifold, TB, maf, booster line, etc.
If you hear a change in the idle, you've found a potential leak.
About the IAC reading...are you able to adjust the TB to get the IAC within specs? I believe it should fall between 40 & 60 counts.
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n2xlr8n66 (11-26-2022)
02-13-2013, 11:17 AM
#5
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I made my own smoke system I connected a hose to air intake made smoke and blew smoke through hole in can with compressor and found my intake leak in a minute.Mine leaked driverside intake gasket cylinder 3 and 5.
