The issue, as I understand it, is not that the plug is platinum. The
issue is that all Bosch platinum's are resistor plugs, and the MB
ignition system is designed for a non-resistor plug. In theory, the OEM
non-resistor plug is going to give you a higher quality spark than the
resistor platinum plug.
You need the correct BOSCH plug because of the different way Mercedes
does the resistance thing. There's an NGK equivalent that some people
say works even better. But those are your choices. No other ones will
Need Mercedes parts? http://parts.mbz.org
Richard Sexton | Mercedes stuff: http://mbz.org
bottom line.... if originally there were copper (ie non resistive)
plugs installed then you can put any old 'copper' (ie non resistive) plugs
in there..... it just doesn't matter what brand. You see, in the distributor
there is about 1k ohm resistance and in the boot (the part going over your
plug) there is another 1k ohm resistance. Now you can addd more resistance
via platinum or other 'resistive' plugs (ie they have resistance build into
them) and they 'will' work.... however not as well since the spark 'timing',
because of the extra resistance in the RC ignition circuit, will cause a
slight but important delay and, more importantly, the spark will last too
long and is consequently weaker since energy is conserved.
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