I have a vacuum leak somewhere, help me find it!
07-16-2003, 05:30 PM
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I have a vacuum leak somewhere, help me find it! Okay, I have to have a vacuum leak somewhere. My right bank is reading 25% Ltrims and the left bank is good (-3%). I did have a slight exhaust leak at the collector, which I fixed, I just changed my header gasket, I have used carb cleaner all over the engine to see if I have a leak. I capped off the vacuum lines for the HVAC controls that go to the intake since I no longer have the HVAC system. Where could the problem be? I have had the intake off a couple of times, and this problem was not noticed before I had the intake off the first time, but I don't know where it could be leaking. Could the intake manifold gaskets need changing? My car only has 6000 miles. I'm open to almost anything now. I got an 02 switching code, so I thought about the exhaust leak, changed the 02 sensor, fixed the leak, and still got the code, although I cleared it and it didn't come back the next time I cranked the car. The intake manifold bolts are tight. Could the PCV lines have a hole in them and making it be off that much? I also have a Metco breather, I am changing back to the stock oil filler neck tomorrow. All opinions are appreciated.
07-16-2003, 07:17 PM
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Re: I have a vacuum leak somewhere, help me find it! - to start with, the breather is not the porblem so don't mess with that (save you some time)
its possible that the intake gaskets could be leaking but 25% (very lean) for 1 bank vs. -3% (rich) for the other bank seems like more than just a gasket leak (thats a lot of air difference)
you said you changed O2s right (you have brand new ones)?
do you have ANY exhaust leaks up stream from the O2 sensor (check for holes, AIR system, header gaskets, etc...even make sure the O2 is tight...)....
I don't see how the PCV or the HVAC could be causing your problem (leaking)...if they were leaking, both banks would be lean.....
your problem is something directly related to that bank of the engine starting at the intake manifold to head gasket and working out to the O2......
have you thought about swaping the injectors around (move all bank 1 injectors to bank 2 and bank 2 to bank 1)? you might have one or more bad injectors that are not flowing enough fuel.....
its possible that the intake gaskets could be leaking but 25% (very lean) for 1 bank vs. -3% (rich) for the other bank seems like more than just a gasket leak (thats a lot of air difference)
you said you changed O2s right (you have brand new ones)?
do you have ANY exhaust leaks up stream from the O2 sensor (check for holes, AIR system, header gaskets, etc...even make sure the O2 is tight...)....
I don't see how the PCV or the HVAC could be causing your problem (leaking)...if they were leaking, both banks would be lean.....
your problem is something directly related to that bank of the engine starting at the intake manifold to head gasket and working out to the O2......
have you thought about swaping the injectors around (move all bank 1 injectors to bank 2 and bank 2 to bank 1)? you might have one or more bad injectors that are not flowing enough fuel.....
07-16-2003, 07:18 PM
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Re: I have a vacuum leak somewhere, help me find it! +25% means way lean, which is what the sleeping
O2 sensor will give you as a false indication.
A vacuum leak can't put you -that- lean at high
cruise. Idle, maybe. Look directly at your O2
voltage on the bad bank under different driving
conditions, see if it's low & slow. This sounds
more like the usual headers & cold O2s problem
than a fuel problem to me. Your vacuum leak
would have to be 1/4 of your throttle blade
opening to jack you by 25%.
An unlit propane torch makes a good vacuum leak
finder and doesn't leave solvent all over your
motor.
O2 sensor will give you as a false indication.
A vacuum leak can't put you -that- lean at high
cruise. Idle, maybe. Look directly at your O2
voltage on the bad bank under different driving
conditions, see if it's low & slow. This sounds
more like the usual headers & cold O2s problem
than a fuel problem to me. Your vacuum leak
would have to be 1/4 of your throttle blade
opening to jack you by 25%.
An unlit propane torch makes a good vacuum leak
finder and doesn't leave solvent all over your
motor.
07-17-2003, 03:21 PM
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Re: I have a vacuum leak somewhere, help me find it! Try spraying carb cleaner into the valve cover, if the idle picks up, you probably have a leak on the lifter gally side of the intake gasket.
