So what's the best way to verify that a leaky injector caused my oil contamination?
09-15-2008, 12:52 PM
#1
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So what's the best way to verify that a leaky injector caused my oil contamination?
STFA talks mostly about injector seal leaks, but I did find one post saying to disconnect the fuel rail with injectors attached and turn the key on to pressurize the system.
Is that the best way? Any other ideas?<ul><li><a href="https://forums.audiworld.com/s4/msgs/2846739.phtml">https://forums.audiworld.com/s4/msgs/2846739.phtml</a</li></ul>
Is that the best way? Any other ideas?<ul><li><a href="https://forums.audiworld.com/s4/msgs/2846739.phtml">https://forums.audiworld.com/s4/msgs/2846739.phtml</a</li></ul>
09-16-2008, 10:25 AM
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You'd likely see misfires with a leaky injector. Yes, you can remove the rail with the
injectors attached, but you'll probably need the OEM clips installed to ensure the injectors don't pop out. Not sure about your install, but I didn't reinstall the clips with my aftermarket injectors, so I'm not confident they'd stay seated in the rail properly with the system pressurized.
When I had a leaky injector, I pulled the plug on the suspected cylinder (based on idle misfire logs) and saw fuel in the cylinder and the plug was very wet.
One other thing you can do is install an inline fuel gauge and see if you're maintaining residual pressure per Audi spec. Fuel is held in the rail by the injectors, the FPR, and the check valve on the fuel pump. If any of these are bad you'll lose fuel pressure, so if its not holding it doesn't necessarily indicate a bad injector - just keep that in mind. If you're losing residual fuel pressure, you will likely have noticed the car takes a bit more cranking to start, though.
When I had a leaky injector, I pulled the plug on the suspected cylinder (based on idle misfire logs) and saw fuel in the cylinder and the plug was very wet.
One other thing you can do is install an inline fuel gauge and see if you're maintaining residual pressure per Audi spec. Fuel is held in the rail by the injectors, the FPR, and the check valve on the fuel pump. If any of these are bad you'll lose fuel pressure, so if its not holding it doesn't necessarily indicate a bad injector - just keep that in mind. If you're losing residual fuel pressure, you will likely have noticed the car takes a bit more cranking to start, though.
09-16-2008, 12:45 PM
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I do know that a check valve was not installed when the Walbro went in.
and it does take a bit longer to turn over after sitting for a while, so I don't think that test would work for me.
I'll check again for idle misfires though, and check the plugs and cylinders for fuel. Thanks for your help.
If its not injectors, what else could it be?
I'll check again for idle misfires though, and check the plugs and cylinders for fuel. Thanks for your help.
If its not injectors, what else could it be?
09-16-2008, 03:54 PM
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You can clamp off the supply line and watch the pressure to see if it falls
you need to use a pair of vice grips and something to prevent from chewing into the line, because you need to really pinch down on the line to close it off. There's actually a VAG tool for doing this, but its probably expensive.
If not injectors, I really have no clue. Only thing I could think of would be worn rings....but you'd see that in compression and probably smoke out the exhaust. I suppose its also possible that a clogged PCV might prevent proper release of blowby, but you might want to get a 2nd opinion on that.
Good luck!
If not injectors, I really have no clue. Only thing I could think of would be worn rings....but you'd see that in compression and probably smoke out the exhaust. I suppose its also possible that a clogged PCV might prevent proper release of blowby, but you might want to get a 2nd opinion on that.
Good luck!
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