Spark Plugs: Resistor vs. Non-Resistor - Page 2 - PeachParts Mercedes-Benz Forum

MB-Dude · #16 08-22-2007, 03:41 AM

Quote:

Originally Posted by Hatterasguy

… The FSM is pretty specific about what you can use, I prefer not to backyard engineer things. …

Agreed, as a general rule. But MB owners seem to make claims about having technical data/information, but never seem to be able to produce it. I’m only trying to ferret out answers. I prefer to not blindly follow what MB Engineering states. Remember, these same "brain children" brought us the ML, et.al., mid-90's wiring harnesses, said Techron as a gas additive (any gas additive) is very bad, then changed direction 180º, etc., etc. I simply want to know "why" resistor plugs are not recommended.

The glory days of Mercedes-Benz are in the rear-view mirror. In my opinion, up until the early 90’s, perhaps a little earlier, MB engineering was awesome. After that, quality of engineering and manufacture went down the toilet. We cannot always use yesterday’s thinking with today’s MB vehicles.

Dpetryk – Your post poses a good question, but the original sticky represented the view that resistor plugs are bad. This thinking has been prevalent amongst MB owners for years. I’m not completely against the concept of non-resistor plugs use only, but struggle with not knowing why. And no one seems to be able to produce data (other than subjective personal experience or “the manual says so”). Inquiring minds want to know.

Quote:

Originally Posted by ASaltyDog

Say, can I use synthetic oil with resistor plugs?

Besides, real men don't need spark plug wires (et.al. 119/980)

Not sure. What does your MB Owner’s Manual say on the subject of synthetic oil use with resistor spark plugs? That's the standard response. Mine is vague on the subject.

Quote:

Originally Posted by JamesDean

this ***** is confusing. heres a question: why doesn't someone just ask mercedes? like their engineering team. heck I'm gonna email them and see what their official response is.

roar.

email sent to the Classic Center. We'll see what they say...

Of all the posts, this is the one I’m really watching out for. Yes, I could have e-mail’d the Classic Center myself, but I fear I would get a much generalized answer. Perhaps you might receive a better response. If I had contact information for MB Engineers directly, I wouldn’t be futzing around here with a no-win thread entitled Spark Plugs: Resistor vs. Non-Resistor. Regardless, I look forward to reading the reply from the Classic Center.

Quote:

Originally Posted by srjulianchivis

A simple question: I have installed Bosch platinum plugs #4020 in a 110 engine - there is no "R" in the number. (I could not care less about radio interference as all staions in the SF Bay Area now suck anyway). So are these plugs resistors or not?

Not sure. Here is the official Bosch Spark Plug Designation Guide… http://www.boschautoparts.com/NR/rdonlyres/C77B3446-232B-4AEC-AFA9-AD05F2A0A2AD/0/DesignationCodes.pdf
Sorry, can’t speak to the SF radio stations as I haven’t lived in the Bay Area for over 1-1/2 years.

Quote:

Originally Posted by cdplayer

… Then I read MB spark plug wires offer resistance in themselves. So by using resistor plugs, I was actually not getting a full burn on my fuel. …

Hmmm… Just out of curiosity, when was the last time the plug wires were changed? As a rule, as plug wires age they increase in resistance. I’m surprised the resistor plugs, by themselves, caused the small amount of soot.

mctwin2kman · #17 08-22-2007, 10:06 AM

They used non-resistor plugs due to the plug wires, cap, and rotor all have 1KOhm of resistance built into them. By adding more resistance to the mix using a resistor plug you will not get the required spark, at least not all of it. Therefore you may not burn your air/fuel mixture as efficiently and thus waste gas or put more carbon in your combustion chamber. I have used both platinum and non-resistor plugs in my 190 and I can tell you there is a difference and the non's work better and the engine runs better. I also switched to NGK wires as they stay within spec warm or cold where I found Beru and Bosch that did not.

MB-Dude · #18 08-22-2007, 12:14 PM

Quote:

Originally Posted by mctwin2kman

They used non-resistor plugs due to the plug wires, cap, and rotor all have 1KOhm of resistance built into them. By adding more resistance to the mix using a resistor plug you will not get the required spark, at least not all of it. Therefore you may not burn your air/fuel mixture as efficiently and thus waste gas or put more carbon in your combustion chamber. I have used both platinum and non-resistor plugs in my 190 and I can tell you there is a difference and the non's work better and the engine runs better. I also switched to NGK wires as they stay within spec warm or cold where I found Beru and Bosch that did not.

Makes a lot of sense for engines with wires and distributors. However, my '96 SL600 has coil packs on top of each plug - 12 of 'em. Now there could be resistance built into the electrical stub from the coil to the actual plug, but I hesitate to dismantle a coil pack simply to investigate. Could this be why my V12 seemed to run better with Bosch Platinum+4 plugs, while the more traditional distributor/wires engines do not? Don't know, but I would sure like to find out.

dpetryk · #19 08-22-2007, 12:32 PM

I'm still waiting to see the TSB.

petaling · #20 08-23-2007, 09:07 PM

Quote:

Originally Posted by manny

Please don't generalize.
M-B specifies resistor plugs in some engines & none-resistor plugs in others.
So, if you want to make your own rules go for it ( and live with the consequences ).

Have you tried getting non-resistor plugs from the dealer for a 15 yr old W124?Last time I went to the dealer Mercedes Benz Markham branch,they gave me RESISTOR plugs?
10 years ago,they told me resistor plugs were bad for my car.So what gives?Are they trying to kill my car and sell me a new one?
I declined and got mine in the UK before I knew about their avail here from this site.

Manny if you know of any source of non-resistor plugs in Ontario,please let me know.!!!!!!!!!!!!

280EZRider · #21 08-25-2007, 02:52 AM

Quote:

Originally Posted by MB-Dude

Agreed, as a general rule. But MB owners seem to make claims about having technical data/information, but never seem to be able to produce it. I’m only trying to ferret out answers. I prefer to not blindly follow what MB Engineering states. Remember, these same "brain children" brought us the ML, et.al., mid-90's wiring harnesses, said Techron as a gas additive (any gas additive) is very bad, then changed direction 180º, etc., etc. I simply want to know "why" resistor plugs are not recommended.

The glory days of Mercedes-Benz are in the rear-view mirror. In my opinion, up until the early 90’s, perhaps a little earlier, MB engineering was awesome. After that, quality of engineering and manufacture went down the toilet. We cannot always use yesterday’s thinking with today’s MB vehicles.

Dpetryk – Your post poses a good question, but the original sticky represented the view that resistor plugs are bad. This thinking has been prevalent amongst MB owners for years. I’m not completely against the concept of non-resistor plugs use only, but struggle with not knowing why. And no one seems to be able to produce data (other than subjective personal experience or “the manual says so”). Inquiring minds want to know.

Not sure. What does your MB Owner’s Manual say on the subject of synthetic oil use with resistor spark plugs? That's the standard response. Mine is vague on the subject.

Of all the posts, this is the one I’m really watching out for. Yes, I could have e-mail’d the Classic Center myself, but I fear I would get a much generalized answer. Perhaps you might receive a better response. If I had contact information for MB Engineers directly, I wouldn’t be futzing around here with a no-win thread entitled Spark Plugs: Resistor vs. Non-Resistor. Regardless, I look forward to reading the reply from the Classic Center.

Not sure. Here is the official Bosch Spark Plug Designation Guide… http://www.boschautoparts.com/NR/rdonlyres/C77B3446-232B-4AEC-AFA9-AD05F2A0A2AD/0/DesignationCodes.pdf
Sorry, can’t speak to the SF radio stations as I haven’t lived in the Bay Area for over 1-1/2 years.

Hmmm… Just out of curiosity, when was the last time the plug wires were changed? As a rule, as plug wires age they increase in resistance. I’m surprised the resistor plugs, by themselves, caused the small amount of soot.

I was once told by a very reputable mechanic at MBI Motors in Portland, OR that the original plug wires on my '77 280E were all copper and would probably last forever. The plug connectors - now that is a different story. After scoping my engine, he found two bad ones. I now have all new connectors with the original copper wires, 204,000 miles, recently changed plugs, and it runs great.

280EZRider · #22 08-25-2007, 02:26 PM

I just discovered that the Bosch Platinum plugs I recently installed in my 280E are in fact Resistors. I was also just told by the same parts guy who gave me this info that the OEM plug connectors have resistors in them as well. Today I'm purchasing new non-resistor plugs.

JamesDean · #23 08-25-2007, 03:06 PM

I've not heard anything from the Classic Center yet..just updating everyone on that. I do hope they answer.

ASaltyDog · #24 08-25-2007, 06:58 PM

Quote:

Originally Posted by JamesDean

I've not heard anything from the Classic Center yet..just updating everyone on that. I do hope they answer.

I wouldn't hold your breath, James. MB's not going to posture themselves on an issue like this.

Bill is right, but one must temper his findings. Note he carefully said “on some configurations”. On some cars a resistor in a high voltage circuit can increase impedance AND capacitance, often creating a standing wave. HAMs know it as SWR or standing wave ratio. Again on some designs it can reflect back into the electronics and cause all sorts of mayhem. On some designs it is dealt with fine by run-time self adjustments. Some motors have local coils, one for each plug and no run length of plug wires at all. Some have seemingly mile-long plug wires into aged rotors, some into electronic controllers.

Bottom line is MBs stance will be to recommend whatever plug is in parts inventory at the time. I've seen "R" plugs come and go as OEM recommended and supplied. Worse, it varies by type. You never know what you’ll get, therefore you’ll never know what’s recommended. How many of you remember the platinum craze?

If you ever think you've put your finger on the issue, the plugs handed to you by MB parts will then change and the whole thing starts again.

I still agree with Bill that R plugs on recent MBs is pointless and may even cause problems. But you’ll have a hard time confirming it across the board for all cars and all installations. IMHO this issue borderlines the great oil-type debate started by Henry Ford in 1915

280EZRider · #25 08-28-2007, 06:13 PM

Now that I have installed the proper plugs in my 110 engine, the spark-plug thing makes sense. The older cars, such as the 114, 115, 116 and 123 models, came with resistors in the plug connectors, so non-resistor plugs were not necessary and would in fact create more ohmage than necessary - hence, a cold spark.

Bosch appears to be out of the business of non-resistor plugs; however, NGK still makes them for most applications and they can be found in many parts houses. Of course, the proper gap setting makes a world of difference as well.

Happy motoring, fellow Meche drivers!

lsmalley · #26 01-19-2014, 07:33 PM

So There is a continued debate about reisitor spark plugs vs non-resistor spark plugs. In MB engines that are equipped with non-resistor plugs from the factory many have said not to use resistor plugs. I have always used non-resistor plugs because I was afraid of getting a rough idle and stalling, etc., etc. Well after changing my O2 sensor yesterday, I bought 6- HR9DC (resistor) spark plugs and put them in. I have not noticed any weird idling or stuttering at all. I know this is all a matter of opinion, but I now know that I can safely order my plugs online instead of being raped at the dealership. Also, with the spark plug wires, does anyone know why MB combined Bosch boots with Beru wires? I saw a 92 190E at the junk yard and took a few photos of the wires. The boot is Bosch, but the wire is Beru. They are all original and even have the MB star logo on them.

jhodg5ck · #27 01-19-2014, 07:39 PM

Quote:

Originally Posted by lsmalley

So There is a continued debate about reisitor spark plugs vs non-resistor spark plugs. In MB engines that are equipped with non-resistor plugs from the factory many have said not to use resistor plugs. I have always used non-resistor plugs because I was afraid of getting a rough idle and stalling, etc., etc. Well after changing my O2 sensor yesterday, I bought 6- HR9DC (resistor) spark plugs and put them in. I have not noticed any weird idling or stuttering at all. I know this is all a matter of opinion, but I now know that I can safely order my plugs online instead of being raped at the dealership. Also, with the spark plug wires, does anyone know why MB combined Bosch boots with Beru wires? I saw a 92 190E at the junk yard and took a few photos of the wires. The boot is Bosch, but the wire is Beru. They are all original and even have the MB star logo on them.

You won't see poor idle/stalling... What you Will see are caps/rotors wearing out Sooner, wires more prone to arcing if they are @ all tired..
In the long run you will go through coils and worst case you will cook the EZL... The latter I've been seeing more of in the past couple of years on cars that are New to the shop here/running what's commercially available plug wise.

for 4-5$ a plug Worst case that seems like cheap insurance to me!

Both Beru and Bosch make parts for MB, so anything is possible.

Jonathan

lsmalley · #28 01-19-2014, 07:47 PM

All of that because of a resistor plug? I wonder why the non-resistor plugs are semi-phased out then and no alternative was offered? I'm wondering if I can just unscrew the tip of the plug and remove the resistor then??

jhodg5ck · #29 01-19-2014, 07:58 PM

Yup.
Excess resistance will do that.

NGK and denso still had readily available NR plugs for a Long time..europe has a better selection as well.

resistor is built into the plug. Screw on tip has no effect sadly.

jono

lsmalley · #30 01-19-2014, 08:42 PM

Its a PITA trying to find readily available NR plugs. I have a cousin that lives in Germany and works for the post office, but still, I don't want to have to wait for 2 weeks to get plugs. I was under the impression that you can unscrew the metal tip that screws into the ceramic portion of the plug and there is the resistor inside. So I was thinking you unscrew the tip, take out the resistor through the opening, insert an equal piece of legnth of copper (maybe a cut coat hanger) for continuity, and screw the cap back on.