Giving Bosch H9DC spark plugs a try/1989 300E
 

Just got some on order to see if they make a difference of not in my car and they should be here by the end of the week.

Car is running what it came with when I bought it a few months ago which is Bosch Platinum 2
spark plugs.

My wires are stock and may even be original to the car as is the ignition.

I've read a few post on the subject from the various Mercedes sites and my car does do some weird stuff,but I don't know if any of it has anything to do with the plugs I have in it now. It could just be that it needs attention in other areas,but I bought the H9DC plugs to at least take that out of the equation.

In the future I may just change the system over and run non-resistor wires so I can run resistor plugs as they are a lot easier to find.

I run resistor NGK plugs with the stock Bosch wires and have 0 issues. The whole resistor non-resistor thing is a myth as far as I'm concerned. My car ran worse on the Bosch H9DC0 plugs, and they fouled up to the point of it running on only a few cylinders after about 60 miles. :eek:

Just avoid platinum plugs and el cheapo plugs. Any good Bosch or NGK resistor plug (or maybe the bosch non resistor) should work fine.