PeachParts Mercedes-Benz Forum - Danger: RESISTOR SPARK PLUGS

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I am about to do a tune up on my 190E 2.6, and found this thread. Non- resistor plugs are getting hard to find, has anyone gone with non-resistor ends and boots and just made there own wires to reduce the resistance?

From what I understand the cap and wire ends have a resistance built in, I'm wondering if I need to make some new wires if I can't find non-resistor plugs.

Quote:

Originally Posted by riorust (Post 1768710)

Use the correct spark plugs. :)

Item Number: 0031590403
Main Category: Mercedes Benz
Sub Category: Engine Electrical
Description: BOSCH H9DCO, these are "NOT" resistor spark plugs
Weight: 0.190

I don't understand the many concern. As long as the recommended spark plugs are available as Mr. Hunter stated (with link to buy), why don't simply use them and have no problem? unless it is academic!

I got them at my dealer for 3.32....didn't even ask for the mbusa discount..

i only needed one... long story...

Quote:

Originally Posted by whunter (Post 1768912)

Use the correct spark plugs. :)

Item Number: 0031590403
Main Category: Mercedes Benz
Sub Category: Engine Electrical
Description: BOSCH H9DCO, these are "NOT" resistor spark plugs
Weight: 0.190

Thank you Mr. Hunter, I just ordered six of them for my 1988 300SEL.
I hope their still available.

Phil of FastLane fame advised he had no more :( , bit the bullet and purchased the non resistor F8DC4 from my local dealer. "discounted" to $5.22 each (OUCH!)

I learned some things from my old auto shop teacher, which he was also a trophy winning drag car builder/racer.........

"Don't mess with success".

"If it ain't broke, don't fix it".

So, unless you are building a race/faster car, stick with what keeps you running smoothly on a daily basis, which normally what the manufacturer specs call for.

Some truth in several posts

Quote:

Originally Posted by stevebfl (Post 1730884)

Just to muddy up the works I can tell you that the ammount of energy used in every coil firing is the same. The secondary disapation of that energy is done by voltage over time. The conditions the coil sees on the secondary are varied. They include the wires, the state of the plugs, the entire current path, but most importantly the environment in the cylinder. The disapation is easily observed with a secondary ignition scope and I can tell you from thousands of observations that neither the activation voltage nor the burn time is changed by resistor plugs. The condition of the spark could change, but the premise of this discussion is the load on the module. It is my position that the module could care less.

I don't believe any of this affects modules as they only control the current through the primary which is determined by the primary resistance and the modules internal circuit design. MB uses current limitation by anticipated firing point. The only way to change the current is to increase the rate of current ramp.

THANK YOU !!! :D

I have been reading this thread thoroughly. I am new to this forum, and wanted to see what kind of members we have here, abd if the info given was correct.

I see there are those that don't know (non-techs), but want to know. They would be wise to read alot, and from other sources, too. In other words, don't base your home repairs on all that is said in a forum.

I see there are some that know alot (from personal experiences, their buddys, & internet reading), but not certified techs. They help get things going in a thread, as their comments cause discussion. The problem here is that it is usually only bits & pieces that are correct.
Those comments should lead the wise reader to do some research to check the accuracy.

And......I see some comments from actual trained, certified, and working technicians. This is good, as they give relavent & pertinent data that can be easily verified with a bit of research.

Read the entire thread if it interests you, because by the time you get to the end, you may wind up with enough correct info to understand what is being discussed.

Quote:

Originally Posted by skhagen (Post 1760584)

http://www.eng-tips.com/viewthread.cfm?qid=168506&page=1

I just read this whole thread. I can tell them (you) from personal experience at my shop, that the coils start going bad in a 4.6L Ford engine after 100k miles. Simple as that. They just start going bad, internally.

Also, if water gets down in the spark plugs area, misfires are the result, and that may cause the coils to go bad too.

takes the BOSCH F8DC4
MB# 0031596703

This answer is for a customer. :)

The 2000 E-class Operators Manual states that for the E320 & E430 - Bosch F 8 DPER (Non Resistor), NGK PFR 5 R-11 (Resistor) and Beru FGH 8 DPUR X2 (resistor unknown) are recommended/acceptable. However for the E55 AMG Bosch F 8 DPER (Non Resistor) is the only one recommended. The new resistor plug FR 8 DPP33 is the replacement for the discontinued Bosch F 8 DPER (non resistor) and I assume is acceptable in an E320/E430 as a resistor or non resistor are recommended/acceptable. I have to wonder why both NR & R plugs are recommended/allowed and what an E55 owner should do for a replacement.

I've read all these postings and I'm still confused. I need new wires because some of the plug boots on my 300SE came apart. I think they are the origonal wires and the coil wire is burned at the clip on spot on the distributor.

Would it be safe to think that regular wires, in bulk at the local car store, and resistor plugs would be OK to run?

I'm in the middle of replacing the head gasket on my M103 300SE and I have the head off.

I'm a little confused, not only does the whole thing not really make any sense, but is that list of 5 plugs or so the only non-resistor plugs? some of those look to be very similar to mine, as far as the part # is concerned, but mine aren't up there. I bought my car used and I don't know if these plugs are original or not.

I just went to a mercedes benz dealership, The mercedes dealership on Steven's Creek in San Jose, and my car originally had H7DCO's and when I went there I gave them my car info and they had required the H9DCO's. I'm gonna go with the dealer info on this one because I don't know my car's history. I have 91 300E 2.6

I just got a 380 SEC and the people I got it from are not experienced as it is quite obvious- I will bet that they in their good intentions, put whatever barney at the local pep boys told then for spark plugs. I will report back- getting greasy this weekend!