Recommended Plugs
 

Hello,
Does anyone know what Mercedes-Benz recommends when replacing or purchasing Sparkplugs, for 1990 E190 2.6.

copper not platinum. Also non-resistor plugs. Lots of brands will do. I happen to have a stash of bosch that I picked up last year, but champions work just fine and are a lot easier to find.

-CTH

I have used NGK iridium plugs on my 1995 E320 with no issues. They engine runs smooth. http://www.ngksparkplugs.com/products/cars_trucks_suvs/iridiumintro.asp

What Mercedes recommends, if you go by what their electronic parts catalog says, are the following:

1) Bosch H9DCO
2) Beru 14K-9DUO
3) Champion S12YCC

Many MBz enthusiasts also recommend the NGK BP5EFS plugs for the M103 engine. All four of these plug models are copper, non-resistor plugs; that seems to be the key, although there are ample testimonials here and elsewhere that Iridium plugs work well. I just don't see that the high cost of Iridiums makes sense for an engine that is recommended to take copper, non-resistor plugs.

plug caps
 

at the plug end the ignition connectors do become conductive with age ,throughly clean them or replace the leads if the inner rubber is gooey. a noticeable smoothness at idle and acc .