I value your opinion Duke BUT I have to say that I am using the Bosch +4 copper plugs and I can honestly say its not a marketing gimmick. Its been on for about 5k miles and they are not fouling, the idle is smoother and the acceleration is better. Note this is not because I switched from old plugs. I actually had new regular DCO plugs in there for 1K and I took them out and put them aside just to give these a try. I was expecting the worse and I'm pleasantly surprised.
Platinums on the other hand my car hates with extreme prejudice

Thanks for the link Yal! I noticed on their site, the spark plug link is "under construction", so I guess I'll give them a call.

I replaced the OE DC0s with "Bosch Platinums" (single electrode) at 15K miles. By 30K miles the idle roughness and emissions problems started. I believe intermittent misfires were causing both.

I switched to Bosch HD9C, and have been using them ever since. I inspect then at 15K and replace at 30K. The idle is not perfect and emissions are still high, but all is better than with the Bosch Platinums.

Nothwithstanding anecdotal evidence, based on my knowledge of ignition and combustion in spark ignition engines, I will not use multiple ground electrode spark plugs.

The archives are full of problems from other than the OE type non-resistor spark plugs. In most cases, installing the correct standard or HD electrode non-resistor plugs solved the problem, but some say that they still had trouble with the HD electrode type plug that went away when replaced with the standard electrode version.

Duke

I have posted this before, but will do so one more time.
My car ( see sign. below ) came with Bosch F-7 KTCR plugs.
These are triple electrode, resistor plugs.
I change them every 30 k miles ( manual suggests to go twice as far ).
What the heck, there is only 4 to change anyway.

__________________
2007 C 230 Sport.

Your car has a different ignition system than M102/103 engines. If the OEM installs multielectode/resistor type plugs, then the ignition system was designed for them. As a rule, later cars have more powerful igntion systems with more per spark energy. This is especailly true for "direct" systems that have a coil for each spark plug.

The best and safest bet in the vast majority of cases is to use the OE or an OE equivalent plug.

It doesn't take too long in the archives to realize that this is very true for the M102/103 vintage cars, and if you use something other than the non-resistor OE type plug, for which Bosch is the only readily available choice, there's a good change you will have some ignition related problems, although the average owner may not recognize igntion related problems. It's only after we harange them to install the OE type non-resistor Bosch plugs that the problems miraculously goes away.

Duke

I did replace my OE coil with an MSD Blaster coil, which has a higher voltage output and performs better at high RPM's than the OE coil.

The Beru UXK 79 plugs are non-resistor plugs. I think I'll be *OK*.. We'll see.

Wonder how they worked out?

Be interested if they work better in older
cis injections?

__________________


83 500 SEC Euro 198K