Mine's a 1995 c280 with 130,000 miles in So. California. Bought it 3 months ago, and it was very smooth...

...until yesterday, getting off the freeway. It started missing like a plug wire fell off. It barely idled at around 500 rpm. Usually it is around 800 I guess. Autozoned and Kracken want to sell me a scanner and the gals at the aftermarket shop want to charge me for plugging in their scammer.

It has always stumbled at 1/3 to 3/4 throttle, like my wife.

No fluid leaks and oil/coolant are clean and good looking, unlike my wife.

Should I pull the spark plugs?

Today after reading this site's posts:
This morning I drove it to the parts racket to get some plugs. It ran better, having lots more power than yesterday. But it still was missing on at least one cylinder.

I pulled the old Bosch sPlatinum plugs (photo) and installed some NGK regular ones. I have pics available of the coils if you want to see them, but all that ignition gear looked really nice, like there wasn't anything wrong with it.

It idles better - around 700 rpm and has more power. Certainly not about to quit like it felt yesterday. But, it still misses.

Ideas?

btw, I need to get it smogged. I wonder if I could save a diagnostic charge by trying to get it smogged and maybe they would give me some ideas or the codes or something.

Thanks folks!

79 300d
84 380se
95 e420
yay!



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Loping is usually vaccum related causing the idle to surge up/down never consistant. This can be MAF sensor, vaccum lines, throttle body gasket, dirty throttle body, throttle position sensor,or even intake manifold gasket. The rough idling can be caused by a bad plug/plugs, bad wire or combination of both. If your still running stock wires that can be the culprit. A bad plug can cause these symptoms also from a poor spark.

 

Hi mello,

Thanks for the quick reply.

Here's a pic of the wires, etc. They read NGK copper silicone. Are they stock?

Thanks


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I don't think MBZ would use NGK. Usually Japanese automakers use NGK wires. It's sorta like apuzzle. You will have to start from the most basic then work to the more technical sorta hit or miss. Most technical being a bad coil.