Resistor or non-resistor plugs
 

I am preparing to do a full tune up on my w201 and was wondering if there is aany known adverse reactions with using resistor spark plugs vs. non-resistor spark plugs for my car.

if you do a search on this you'll find a lot of arguing and such back and forth between the two sides.

I just stuck with non-resistor types like my manual called for.

Denso T20EP-U
NGK BP5-EFS

******** has them or

http://www.clubplug.net/ stock number 5031

You might even be able to get the NGK's at your local Napa Auto Parts.

Me too!

i have resistors in..... bosch copper core....

I put in resistors and non-resistors, noticed no power difference. I bet on a dyno there would be very little, if any difference.

Just stick with copper core and stay away from the Pt + the four prong deals

Mercedes says non resistant plugs. I personally think arguing with someone who has been making cars for 125 years is a little redundant.

Non resistor plugs because the wires have resistance. Thats is what I have read online AND on my wires (8 ohm I think). So if you have wires with no resistance (well very low) then resistor plugs.

Maybe that's why you're having problems (from another thread) immediately after changing plugs.

Get the plugs from your Mercedes dealer. PepBoys doesn't carry Mercedes parts.

I agree. I think a lot of you on this forum are very smart and have helped me a great deal, but in a situation like this where everyone is saying something different, I'd rather just bend over and go get raped for a few extra $$$ by the dealership. At least that way I know that I am getting exactly what my car was engineered for. Resistors may work, but I'm not willing to try it because I only have the one car and not enough knowledge to fix major eff ups with the engine. ;-)

This topic
 

is almost as popular as an oil thread.

Non-resistor copper core plugs are specified for our cars and should be used. The comment regarding wire resistance is valid. I had valve seals replaced on my M117 engine a year ago and the very knowledgeable MB specialist independent installed Bosch resistor plugs without me asking him to do so. I told him I would go ahead and try them. The car ran and started o.k. for about 6 months then performance started to fall off. I replaced those plugs with NGK BP5ES, a copper non-resistor plug that is commonly used in place of the Bosch non-available plug. Performance is back to the way it should be.

The comment regarding sourcing plugs from Pep Boys is nonsense. Mercedes Benz does not make things like spark plugs. Back when the proper Bosch OEM plugs were available you could get them from Pep Boys. Going to the dealer for every minor, non specific part will only enrich the dealer and make you poorer.

and some dealers wont have the non-resistor ones in stock, they may give you the bosch resistor plugs regardless and just tell you that they'll work no problem.

Get them online, I think Fastlane even has some...

Well, it's worth trying dealers if your local auto parts store doesn't have the right specification plugs. Inspect them before buying first, of course!!

I've got my plugs at my local parts guy at the dealer - Bosch H9DC0 for my '89 190E 2.6.

I got H9DCO non-resistor for $3.29/each at my local dealer. Go there first.