After turning off the engine...
06-21-2006, 01:15 PM
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2016 C450 AMG
After turning off the engine...
Does anyone else notice a vibration for a split second after you turn off the engine? Its like the pistons are slowly coming to a stop, but still have a pump or two left in them. The car shakes once or twice while this is happeneing.....is this normal??
06-21-2006, 01:35 PM
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Originally Posted by chem1441
Does anyone else notice a vibration for a split second after you turn off the engine? Its like the pistons are slowly coming to a stop, but still have a pump or two left in them. The car shakes once or twice while this is happeneing.....is this normal??
That's not normal. It sound like unburnt fuel still making the engine turn. Anybody else know?
06-21-2006, 05:53 PM
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What type of fuel are you using? This can happen when you use a low octane fuel. Our cars have a relatively high compression ratio (10.25:1 if I remember correctly). The compression of the air creates heat which can ignite fuel if the octane rating is not high enough. This should, however, not happen in a fuel injected car, where electrical power is needed to sustain fuel flow (injectors don't work w/o electricity). This happens in carbureted cars alot, but I've never heard of an injected car running into these issues. Might be worth a shot to use premium fuel if you aren't already, especially in the summer.
06-27-2006, 10:58 PM
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2016 C450 AMG
I definately use premium fuel....in Maryland that usually means 93 Octane....but I have noticed a rattle from underneath the car (around 40-50mph) if I accelerate moderately. Sometimes its worse than others.....so maybe the CAT Converter is bad...... 
Last edited by chem1441; 06-27-2006 at 11:09 PM.
