w203 cdi strange problem...

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117

Member
Joined
Oct 28, 2005
Messages
59
Location
Exeter, Devon
Car
BMW 650i Sport, Range Rover V8 Autobiography, Ex 01' S500, '04 C200 CDI Coupe, '95 C200
Hi guys,

Strange issue with my w203 c200 cdi coupe auto, basically when driving at low speed in traffic, when I take my foot off the throttle the revs go very low and the car noticably vibrates before going back to normal idle speed.

Any ideas guys, or is this a normal issue....

thanks....
 
Hi 117, My E300TD 170k has this sort of hard vibration at idle - 600 rpm when the revs are increased a touch it goes away. During starting and stopping the engine, it goes through a tough vibration and deep hum twangy noise. It was first noticable on starting the engine 6 months ago. After 10k 6 months later it is a lot worse and noisy in the car at idle in Drive. Move to neutral revs lift a fraction and it goes. Aux belt is fluttering a bit, tensioner, spring, idle roller, engine mounts, injectors all new recently. I noticed belt flutter - twitching, the belt flutter may be contributory to the deep humming noise around 600rpm. I have noticed pressure pulsing of coolant hoses one would think about the pump but I don't have any cooling or heating problems. In any case I dont think the pump would be robust enough to cause this vibration problem.

None of the auxilliaries seem to be noisy or causing vibration. With a hand touching the top of engine one can feel the hard vibration, but above idle it smooths out unless it is masked by the naturally increased general noise.

These syptoms may not be the same problem as yours 117 but I have added this because I am getting threadbare trying to find the problem. I have checked turbo air pipes and all are sound and do not feel as though they are the cause of vibration.

Cany anyone advise do these cars have crankshaft vibration dampers ? if such damper was failing could it result in harsh behavoiur of the aux belt pulley on the crank resuting in snatching of the belt? and if so would it clear as revs increase ?Would it be noisy?

Is there any trim on idle speed on the pump ? Could injection timing have become advanced after 170 k miles? I have a gut feel that is is a fuel / timing / issue. When one stops the engine it is stationary in a split second. any ideas will be much appreciated. Yours truly Peapod.
 
I had new engine mounts done last year from a local indie and these cured a problem I had previously, which was the gearstick was rocking back and forth under hard acceleration from a standstill.... so Im a little confused as to the cause of the problem.

The problem I described in the OP doesnt always happen, say only 60% of the time....
 

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