plug question - PeachParts Mercedes-Benz Forum

A264172 · #1 10-23-2004, 12:55 PM

I am getting ready to put in new plugs & wires and I notice Advanced Auto Parts gave me platinum BOSCH HR9DPX plugs instead of old regulars (H 7,8,9 DC/DCO).
Guess I am just a little nervous could this be bad for my engine (M103.983)?

Any other tips?

A264172 · #2 10-23-2004, 01:25 PM

Engine's almost cool, any takers?

A264172 · #3 10-23-2004, 01:53 PM

Think I found it here

Quote:

Quote:
Originally posted by pesuazo
Go back to copper bosch copper sparkplugs. And take it from there.

The issue is not "copper versus platinum", but resistor versus non-resistor. About the only reasonably available OE type non-resistor plugs are Bosch Supers, which are available in both resistor and non-resistor versions. Make sure you get the non-resistor version specified in the owner's manual, which should be H9DC. Don't buy HR9DC. The "R" indicates a resistor type plug, and almost all other comparable plugs, including popular "platinum" replacements such Bosch Platinums, are resistor type.

Resistor type plugs may cause increased idle roughness and emissions, but the evidence is mostly anecdotal.

Duke

Looks like I have to heat her again up and go get replacements.

P.S. Nothing like a good conversation with yourself.

mpolli · #4 10-23-2004, 02:57 PM

On the one hand, I agree with all 3 of you... On the other hand, there was a thread recently where it was basically stated that platinum plugs are cra*. This thread was called "STARMARK & INDY GARAGE". So you might check that one out.

Mike

psfred · #5 10-23-2004, 03:07 PM

I've put both Bosch Platimun plus 4s and Champion copper cores in the TE, no difference.

My friend the mechanic only uses platinum plugs these days, as they are all resistor plugs originally.

If you have idle problems, switch back to the coppers, but otherwise the platinums are fine, I use them in everything with no problems.

The only time you get trouble is if you have too high a resistance in the wires, ends, and plugs combined, and most replacement wire sets these days aren't resistor (or have the correct low resistance ends).

Peter

Duke2.6 · #6 10-23-2004, 04:59 PM

My suggestion is to buy a dozen Bosch Super H9DCs from Fastlane. One for now and a spare set for later. They are less than $2 each and should be good for 30K miles.

The OE type "heavy duty" electode (suffix "0" as in H9DC0) are more expensive, but not worth the higher price. The standard electrode H9DCs are just fine.

Duke

ericgr · #7 10-23-2004, 05:36 PM

I had put the w9DC0 (0 on the end, bigger center electrode) and the car had a HUGE miss at idle-- 1984 380SL. I posted on that experience and complained to Mercedes who gives owners that plug. I even got Bosch on the phone with me and they agreed that plug could ause issues in my car. I learned this lesson the hard way. Yes in some cases some people have no problem switching up plugs to platinum or whatever. But I have experienced, and I have seen so have others, VERY EXPENSIVE troubleshooting efforts that in the end was a simple plug issue. I tell people to read the owners manual and use the plug originally recommended for the car period. There is no good reason to introduce the unknown of a different plug typically. Vor me it is a Bosch W9DC and after putting those back in the problem went away.

A264172 · #8 10-24-2004, 02:02 AM

Traded in on BOSH H9DC's NAPA had 6 left @ $1.09/plug
antisieze on threds
20nm torque
new BOSH wire set $88.00
metaic heating duct tape repair to shattered housing

next up exaust
got to get a new dremmel (burned it out on some plaster lathe) so I can cut those g@% d#$ bolts off the upper bracket

2 mufflers in garage
running on straight catalitic converter.
15mpg

goodnight all

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