PLEASE HELP ON TRANSMISSION OR IDLE PROBLEM?

[David Ma <MaD@xxxxxxxxxxx>]

Hi everybody,
I have a question regarding idle speed on 92 E 36 325I automatic!  When you
start the car, it should stay around 900 rpm, right?  If you put it in D or
R, it will stay around 600 rpm or a little higher?  After it has been driven
for half hour or so when you get to the destination and put it in D before
you turn it off, What rpm it should idle at?  Please advise!  Mine stays
close to 550 rpm and the transmission area makes an intermittent high
pitched humming noise when the car has been driven for a while!.  The dealer
told me the transmission needs to be replaced, but I think it is the idle!
If I give it a little fuel, I don't hear the noise, but if I take my foot
off the gas, the noise comes back!  Does the internal of the transmission
control the idle or there is some valve or sensor do the job?  I replaced
the transmission fluid and the noise problem stays. I don't have any tranny
problem when driving it!   The car had a tranny leak at around 30K and
dealer fixed the problem. At 56K, transmission fluid was changed!  Please
let me know if your idle speed is the same like mine, if not, please e-mail
me!  Thanks!
David  

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