1996 UK E320 Engine revving at idle when hot.

E320 (210 series engine) automatic.
I have a problem that - when warm the engine revs pulse when stopped with auto in drive ( ie when stopped at traffic lights).
Has anybody any idea of the cause.
TIA
Tony Hann
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does it do this in neutral aswell, or just D?

possibly an air leak on the intake side
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No, the revs tend to settle in idle.
Thanks for your comment I will check for air leak on intake.
Tony Hann
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hm ... if it was an air leak, then engine would rev when not in gear also. it may be that the clutch packs in the trans are on their way out, or/and slipping
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In fact I have checked today and the problem does occur in neutral and park. Probably less noticeable due to not having to work against transmission load. I have noticed, at times, a high pitched whistling sound at low revs, could this be the clue?
Once again I appreciate your help.
Tony Hann.
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1996 UK E320 Engine revving at idle when hot. Group: alt.auto.mercedes Date: Mon, Jun 23, 2003, 7:39pm (PDT+7) From: snipped-for-privacy@gif123.demon.co.uk E320 (210 series engine) automatic. I have a problem that - when warm the engine revs pulse when stopped with auto in drive ( ie when stopped at traffic lights). Has anybody any idea of the cause. TIA Tony Hann ****************************************************** MAS Meter Remove connector and see if rev pulse stops This might trigger Check Engine Light CE light can be re-set by disconnecting battery for a few minutes, but you'll need to re-set the radio with its security code. Eventually your rev surges will get worse, and your CE Light will come on, typical sign of a failed MAS meter If you don't know what the MAS meter is, its a hollow plastic tube with a connector on top located between the air cleaner cover and a pipe going to the intake manifold. Here's a link to a pic: http://www.importeccatalog.com/start.wws?cookieID=0K40SUN24
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Thanks for the information. I will try as you suggest.
Thanks for the link
Tony Hann
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I have had replaced the MAS Meter with a borrowed new unit and the problem still exists ! Do you have any other possible cause of this problem. I am taking the car to the South of France in ten days and I am worried that further problems will develop.
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