Non-resistor Spark Plugs - Can they be found? - PeachParts Mercedes-Benz Forum

bolomiester · #1 03-16-2009, 10:44 AM

Quote:

Originally Posted by pawoSD

Here is my interesting story:

I got my 300E last November....it was misfiring....so I replaced the distributor/rotor/cap and it got better, then I pulled the plugs....it had nasty old Champion Resistor plugs in it.....I went to the dealer and actually acquired a set of Real-deal Bosch non resistor H9DCO made in Germany plugs. Put them in, it ran amazing....for 60 miles....then it began misfiring bad and was way down in MPGs/power.....so I pull the plugs again, they were horribly coked and dirty. I went to autozone and got a set of super cheap "Splitfire" resistor China plugs.....put them in.....it ran great again for about 100 miles....then back to the same old....but even worse than before....so I put the formerly retired champions back in, but had cleaned them. It ran "ok" from here on....(several hundred miles)....but I still wanted to replace them with good plugs. This time I ordered NGK Resistor plugs online....put them in, and it ran beautifully.....it has been running those plugs for about 2 months....and close to 1500 miles....0 issues. Idles so smooth you can barely tell its running! Plenty of power.....good MPG's....I've been getting 20mpg even when I am a leadfoot.

Moral of the story, get good plugs, and the Resistor ones work fine. NGK are good, and the Bosch Resistor plugs are probably fine too.

The whole resistor/non-resistor thing is a myth.

The only important thing is to not use Platinum plugs as the electrode is too thin.

My 300E does the start/stall thing too....I am guessing it is the injectors or fuel accumulator....but it starts fine after 2-3 seconds of cranking on the second try....so I am not going to worry about it. Once it starts it runs perfectly.

That is a very interesting story, and valuble as well. I didn't want to buy the Champions because of poor reports from some of the forum members, but I was even less willing to buy the India made Bosches, again because of negative reports from forum members. However, I knew the platinums had to go so, your experience with the NGK's is much appreciated. I've used that brand on other cars (Volvo & Toyota)and had great luck with them. Looks like I'll be ordering a set today. However, I'll leave the Champions in for awhile to see what happens.

teezer · #2 03-16-2009, 11:41 AM

i'm sitting on 17 boxes (170 plugs) of nos H9DC0

6 for $25.00 shipped to U.S.

pawoSD · #3 03-16-2009, 02:15 PM

Quote:

Originally Posted by teezer

i'm sitting on 17 boxes (170 plugs) of nos H9DC0

6 for $25.00 shipped to U.S.

That's more than I paid for them at the dealer...though with shipping I suppose its ok.

Paid about $11.50 for my 6 NGK's.

Why do you have so many??

teezer · #4 03-16-2009, 07:45 PM

Quote:

Originally Posted by pawoSD

That's more than I paid for them at the dealer...though with shipping I suppose its ok.

Paid about $11.50 for my 6 NGK's.

Why do you have so many??

bought out the inventory from a farm implement place in oklahoma, evidently these were used in generators and other equipment of some sort

having been in the parts game years ago, i learned to stock up when something has been discontinued, i should never run out

RBYCC · #5 03-16-2009, 01:00 PM

Quote:

Originally Posted by bolomiester

That is a very interesting story, and valuble as well. I didn't want to buy the Champions because of poor reports from some of the forum members, but I was even less willing to buy the India made Bosches, again because of negative reports from forum members. However, I knew the platinums had to go so, your experience with the NGK's is much appreciated. I've used that brand on other cars (Volvo & Toyota)and had great luck with them. Looks like I'll be ordering a set today. However, I'll leave the Champions in for awhile to see what happens.

NGK's are great and still available !
I run BP6EFS in my M103-12V twin turbo.
They are one step colder then the BP5EFS which is the same range as the Bosch H9DCO.

Cal Learner · #6 03-16-2009, 04:12 PM

Quote:

Originally Posted by RBYCC

NGK's are great and still available !
I run BP6EFS in my M103-12V twin turbo.
They are one step colder then the BP5EFS which is the same range as the Bosch H9DCO.

Right about NGKs, they are great. Out of curiosity, why did you step down to a colder plug? What difference have you noticed?

RBYCC · #7 03-17-2009, 08:18 AM

Quote:

Originally Posted by Cal Learner

Right about NGKs, they are great. Out of curiosity, why did you step down to a colder plug? What difference have you noticed?

I use a colder plug because I'm running 7+psi boost with twin turbos.
Gap at thirty thousandths.
Limits detonation.
Stock or older engines should run the specified heat range and if an oil burner may consider a step up in heat range.

Strife · #8 03-16-2009, 11:49 PM

Quote:

Originally Posted by RBYCC

NGK's are great and still available !
I run BP6EFS in my M103-12V twin turbo.
They are one step colder then the BP5EFS which is the same range as the Bosch H9DCO.

I am very happy with NGK and am not having a problem finding them, and they are cheap too!

The importance of using a non-resistor plug in a system (coil, cap, rotor, and wires) designed for them has been beaten to death in this forum. My opinion FWIW: different resistance from that originally specified will change the waveform, height, and duration of the spark. Not by much, but maybe by enough to cause a problem.

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