Chirp/tweet when releasing the accelerator pedal

[WRe]

Hi,
maybe someone knows this phenomenon and can help: Always when I release  the accelerator pedal/gas e.g. downhill I hear a chirp or tweet coming from the front/engine or underneath. Could it be the throttle valve or the flexible disk?
Any ideas? Thanks!
...Wolfgang

[WRe]

... and it disappears instantly when I hit the gas/accelerate.
No ideas?
...WRe

[Tyler S]

A whistling or chirp when releasing the throttle can sometimes be a vacuum leak somewhere. May only happen under decel because of the high vacuum created. Check around the throttle body like you suggested. Esp the line going to the distributer. Also intake manifold and brake booster hose. Spraying carb cleaner around these areas with the engine running can help to find. If the rpm surges, even a little, you found the leak.
Also check that the throttle plate is closing completely and is clean.

[WRe]

Hi,
today I had time to check everything you suggested. I found a very dirty throttle plate, a lot of carbon deposit at the edges. I cleaned everything - from outside without removing it - tightend everything very carefully and it helped. The  chirp/tweet is gone and  the engine idle seems more precise and little bit lower.
Thanks to everybody!
...WRe

[WRe]

Hi,
my halloo was too early because the tweet came back.
Because of a loud clatter underneath I opened  the revision plate on the right side of the tunnel and noticed that the angle of linkage rod of the 3-way solenoid had a little clearance and this causes the tweet when you release the acceleration pedal means the 3-way-solenoid moves back.
Don't know what I can do with that excepted greasing/lubricate.
...WRe