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W140 Mercedes 500 SE, 1992, European, 410.000 km
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Discussion Starter #1
AlldataDIY says that camshaft sensor provides signal for engine management computer from start to ca. 600 rpm. so why some people report that after replacing this sensor the rough idle became normal again? i have read such reports on internet but not for W140 specifically. One example was for C280 (1998).
 

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Mercedes S500 - W140 && S500 W220.
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AlldataDIY says that camshaft sensor provides signal for engine management computer from start to ca. 600 rpm. so why some people report that after replacing this sensor the rough idle became normal again? i have read such reports on internet but not for W140 specifically. One example was for C280 (1998).
That is not exactly what the camshaft sensor is suppose to do.

The camshaft sensor will adjust it's value when you are accelerating, or decelerating and thus commanding the car's computer to adjust fuel injection and O2 adjustments.

At Idle value, the camshaft sensor's input is not worth too much.
This is why, when a faulty sensor is removed, the "idle" returns to normal.
 

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W140 Mercedes 500 SE, 1992, European, 410.000 km
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3,616 Posts
Discussion Starter #3
interesting what you say. i will wait also for other members to comment my question.

my mechanic claims that camshaft sensor (not camshaft solenoids) is only for cold start.

did you maybe describe function of camshaft magnets - solenoids?
 

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1997 S600 (sold)
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4,660 Posts
AlldataDIY says that camshaft sensor provides signal for engine management computer from start to ca. 600 rpm. so why some people report that after replacing this sensor the rough idle became normal again? i have read such reports on internet but not for W140 specifically. One example was for C280 (1998).
I believe that is correct. My understanding is that the camshaft sensor is used by the computer to find top-dead-center for cylinder #1 when the spark plug needs to fire (versus on the non-firing top-dead-center). When that is located, the computer may not need the cam sensor anymore. But, I don't claim to know every detail about everything in the system.

As far as anecdotal reports on idle improvement, I can't comment.

Brett
 
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