Does anyone know the pros/cons of using the Bosch Platinum+4 Spark Plugs in MB 8 cylinder engine? It's time to replace plugs and I was thinking of using the Platinum+4.

92 400SE W140 S-class

Thanks,
Russell

Car year and model?
Also do a search on the words "platinum plugs'.

There is a ton posted on this topic.
The board consensus is clearly against them.
That said, I have used them on a variety of vehicles, including MBs, and observed no problems.

A number of tests in various publications have ruled them "not worth the money".

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1986 300E 5-Speed 240k mi.

I've tried them in two different vehicles, and removed them shortly after.. Both times for rough idle issues??? Don't know why, but they just didn't idle well.. I haven't tried them in the Benz, and I won't waste my time..

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89 300SEL Money Pit

92 Blown Buick Ultra Pimpmobile 220K and adding 1K per week

88 Wagoneer Slightly modified (Not for soccer moms)

04 Kia Sedona with every option... NICE

I like them in my Chevy truck, but my M-B gets what " The Book " calls for ( Bosch Copper ).

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2007 C 230 Sport.

I just talked to the local foreign car man in Corpus Christi (he fixes all kinds of foreign cars) and he said that platinum plugs are a waste of money. Two dollar apiece name brand plugs work just as well.

kip Foss

You have to remember, platinum plugs were invented for one purpose only.......longevity.
When vehicle mfgr's started out-doing each other with " extended service intervals ", i.e. 100 k miles between plug changes, ha, ha, ha,.
The reason for platinum, if your going to pay a mechanic $ 100.00 to change a set of plugs,( because on some vehicles they are virtually in-accessible ) and then ***** about the labour, his answer will be " yeah, but you only change them every five years".
Personally, I think anybody that runs plugs 5 years and 100 k miles should be shot & peed on, and not necessarily in that order.

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2007 C 230 Sport.

Manny:

Relocate to the U. S. and run for president next time around.

Love your attitude.

I don't know if they would let me re-locate to the US.
My attitude got me kicked out of Germany 36 years ago.

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2007 C 230 Sport.

In my testing, the Bosch +4 and the NGK 3’s only advantage is allowing 4, or 3, opportunities for a single spark path, the one better path at any given time get the nod. That may explain some good impressions about the plug, (i.e., a spark path more easily presents itself) but I ask, at what cost? …and why? …when far better spark technology is available. This technology makes marginal most of our mussing about plugs. However, I would recomend NGK because they have the finest ceramics, are well made and are not too costly.

MB spark is amongst the highest energy in the first place. However, ever seen most sparks at the plug? Add the effect of compression, and things seem even less impressive. The bottom line is that we are trying to affect as many air-fuel molecules at one time to effect a positive ignition each and every time. Nothing more, nothing less.

The way to affect the most air/fuel molecules is with increased energy, not increased duration. A stringy spark lasting a longer time still affects only a fraction of the air/fuel molecules than the massive plasma sphere produced with a peaking capacitor. It ignites the leanest and richest of mixtures, and one does not have to use costly spark plugs with multiple spark pathways. Install DirectHits and stop worrying about the performance of your sparkplugs.

Mark Shinnick
www.mastertimer.com

Bosh Platinum Badddddddd I Got O Mine Car Run Like ****
I Replace Om Bosh Run Good 92 400se

The critical issue is resistor versus not resistor, which everyone overlooks.

Most aftermarket catalogs call out resistor plugs for Mercs originally equipped with NON-RESISTIR plugs. You will likely NOT find non-resistor plugs at parts stores, and they will try to sell you a resisitor type plug, which can cause idle quality and emission problems.

Bottom line is to use ONLY the NON-RESISTOR Bosch OE type plugs - for example H9DC for M103 engines, which are readily available from Mercedes parts specialists like Fastlane.

Even if you buy from a store that sells Bosch plugs, they will likely hand you a set of HR9DC - WRONG PLUG! It's a resistor type.

Any plug you buy that has an "R" in the number is likely a resistor plug, and it's likely to cause problems.

Duke

I've got a 97 S320 with 120K miles on it. I recently replaced my plugs with Bosch Platinum +2. (They were on sale for $3 apiece and I was unwilling to pay double that for the +4 variety). I have run about 5K miles on these plugs and have no complaints. Smooth idle, and plenty of power at both low and high RPM. I am about to do the same to my wife's 98 S420.

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KCScout
98 S420 My Wife's Baby
97 S320 My road car
83 300D My old road car (love that diesel)
81 300SD Wife's former Baby
81 240D A fun stick shifter
71 220D My first one

The resistor value is printed on the ceramic of the Bosch plugs.
R0 = no resistor
R4 = 4KOhm
etc

Just a small reminder for those using Resistor plugs on 104 engines---
These engines already have resistors at each plug inside of the plug connectors . And most importantly, these are not conventional ignition systems , but rather Waste Spark systems .. meaning , each coil fires a series circuit through 2 plugs in order to complete the spark circuit. That is why 3 coils for an IL6 engine.
The wasted spark does not require a high coil draw cuz it is firing on an exhaust stroke [ thus , wasted spark] and is not under the demands of a compression stroke firing. But the system is still taxed beyond a regular ign. as it still has to jump two gaps to complete a circuit.
So , when adding R plugs on top of what is already there , you are doubling the resistance and further taxing both the coils and , more importantly, the switching driver circuits in the ECU. As of late , these ECU have been popping the heat sinks right off the switching transistors due to eccessive current draws . Adding the unneeded extra resistance of R plugs to this series circuit only shortens the longevity of the electronics involved.and they are $$$$$$$$$$$$$$$$

One will note that all 104 engine take the Bosch F8DC4 , non resistor , copper core plug and they run fine with them.
If one finds no misfire problems on 104 ign. with R plats , it is an unusual case and they will have future problems with the drivers and coils way before due .