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Troubleshooting: A4 B6 1.8TQA 'Mooing/Honking' on vacuum-to-boost transition
Hey All,
Some of you may have read my introduction post and know that I have slowly been replacing parts of my emissions/pcv system to improve reliability and condition of my car. I've just recently run a boost test where the system would successfully hold 10-12 PSI of pressure with no major leaks to be observed! Prior to this, I had replaced my PCV (crankcase one-way) as all of this pressure was being lost out of my oil cap. Pic to keep the visually stimulated happy:
In addition to the PCV valve replacement, I have replaced numerous checkvalves, new 710n DV, n75 valve, SJP. Many moons ago, she also got a new PRV.
My continuous efforts have not been make-work projects, or simply 'because', but instead in pursuit of addressing a very specific sound which I will try to describe below:
'Squelch/Buzzing/Honking' sound when partial throttle applied/let off, sounds like it is right behind dashboard on drivers side, only occurs after car is at operating temperature. You can hear the 'honk' when heavier on the throttle as well, usually around the 3K rpm mark when a gear change occurs. After the car has warmed up and the honking has begun, you can distinctly hear the engine ticking away behind the dash at idle, almost as if there were a stethoscope amplifying the idle sound to the gauge panel. (see Youtube video: https://www.youtube.com/watch?v=HACmDLcEQ54)
I will add that I am also experiencing a solenoid clicking behind dash, seems similarly responsive to 'squelch' sound, eg. click when partial throttle on then click when partial throttle off. This only occurs when the engine is cold. I believe this to be related to the brake booster.
I think that the next stop for me will be into a shop to get a professional's ears on this one. However, I must say that I have completed everything to-date on my own, so I am reluctant to admit defeat to this problem.
I would greatly appreciate any thoughts you may have towards a solution!!
P.S. When your alternator fails on the AB-2, don't leave your car overnight with plans on throwing in a new one roadside the following day.
Some of you may have read my introduction post and know that I have slowly been replacing parts of my emissions/pcv system to improve reliability and condition of my car. I've just recently run a boost test where the system would successfully hold 10-12 PSI of pressure with no major leaks to be observed! Prior to this, I had replaced my PCV (crankcase one-way) as all of this pressure was being lost out of my oil cap. Pic to keep the visually stimulated happy:
In addition to the PCV valve replacement, I have replaced numerous checkvalves, new 710n DV, n75 valve, SJP. Many moons ago, she also got a new PRV.
My continuous efforts have not been make-work projects, or simply 'because', but instead in pursuit of addressing a very specific sound which I will try to describe below:
'Squelch/Buzzing/Honking' sound when partial throttle applied/let off, sounds like it is right behind dashboard on drivers side, only occurs after car is at operating temperature. You can hear the 'honk' when heavier on the throttle as well, usually around the 3K rpm mark when a gear change occurs. After the car has warmed up and the honking has begun, you can distinctly hear the engine ticking away behind the dash at idle, almost as if there were a stethoscope amplifying the idle sound to the gauge panel. (see Youtube video: https://www.youtube.com/watch?v=HACmDLcEQ54)
I will add that I am also experiencing a solenoid clicking behind dash, seems similarly responsive to 'squelch' sound, eg. click when partial throttle on then click when partial throttle off. This only occurs when the engine is cold. I believe this to be related to the brake booster.
I think that the next stop for me will be into a shop to get a professional's ears on this one. However, I must say that I have completed everything to-date on my own, so I am reluctant to admit defeat to this problem.
I would greatly appreciate any thoughts you may have towards a solution!!
P.S. When your alternator fails on the AB-2, don't leave your car overnight with plans on throwing in a new one roadside the following day.
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