[samosali]

1) mercedes recommended bosch F9DC0 for my car
2) i found here

Bosch to NGK cross reference

that replacement for this spark plug is one by NGK; BCP4ES

3) However if i visit NGK web site I can find that they recommend BCP6ES 8some sites recommend also BCP5ES) which is less hot spark plug.

What to do?

Another dilemma is: Bosch replaced their F9DC0 with FR8DC+. I had these in my car in last 20.000 km. How is this possible? How can a spark plug with resistor replace one without it? I spoke with Bosch representative here and he said that resisitor in this spark plug is 6,000 ohm. the spark plug boot on my car has 2,000 ohm inside. What is going on? can someone explain this? maybe additional resistor is not a problem at all but i assume that 2k ohm in spark plug boot is the only resistance which was predicted by car designer.

now i have NGK; BCP6ES in and idle is still shaky. I assume even if temperature value of this spark plug is not optimal, the idle should be ok for coolant temperature 80°C for brand new spark plugs. is this right?

???

thanks.

 

[JimF37]

I always thought that there's a 'resistor' in the 'boot' as you said, so a resistor plug is not needed.

I've been using Bosch F8DC4 and that is the recommended replacement.

 

[samosali]

thanks JimF. You answered my dilemma about the resistor. I share your logic.


So, according to

http://www.ngkpartfinder.co.uk/cross_reference_search.php?part=F8DC4&type=SPARK PLUGS&manufact=BOSCH

NGK spark plug would be BCP5ES and not BCP6ES (like recommended by NGK itself) but it seems better to avoid NGK because MB does not recommend it.

 

[Check Codes]

Generally speaking, you are ALWAYS better off using a manufacturer's application guide than a cross-reference chart.

The latter is one manufacturer's best guess about which of their competitor's products best align with their offerings. Often it's the same, but why take the chance? It's analogous to using a Reebok sizing chart to determine which size Allen Edmonds to purchase.

Bottom line: If you want to run NGK plugs, use an NGK application guide. Bosch for Bosch, Beru for Beru, etc. If they note a resistor and a non-resistor, make your choice accordingly.

That said, manufacturers will often "recommend" their newest and best plugs, which may or may not be appropriate. Sticking an iridium/platinum fine-wire electrode (or multi-tip) plug into an M119 or M104 engine typically does not yield good results, which is the ultimately heralding benefit to a forum like this: you can find out such things before you spend your hard-earned dollars (and precious spare time) installing something that really isn't all that great.

Good luck.

 

[Joflewbyu2]

I went with Bosch's performance recommended Platinum/Iridium Fusion +4 plugs. Smoother idle and easier starts than the OEM plugs. Been in for almost 1 year and 7,500 miles trouble free. Be aware gaps of later cars with D.I. are 1.0 mm (.040") versus .8 mm (.032") of earlier engines with cap and rotors.

 

[nhzruthless818]

to all that think mercedes doesn't use ngk, mercedes does use ngk for amg models the airbox coming from germany has the label stating use ngk double head plugs I will find the part number for it. the bosch +4 are bad because they can burn up the coils head stories of this on the m112-113 engines. but havent tried it myself (I have new coils and wires boots so technically speaking it should be okay)

Bosch F8dc4 is what mercedes recommends on all m119s from 88-99, if you guys didn't know the m119 was introduced with the r129 from 88 upto 02 (longest production benz).

 

[samosali]

thanks, gentlemen.

some facts and conclusions:

1) MB dealer here sold me bosch FR8DC+ 20,000 km ago. This is a plug with a resistor. JimF (and probably many others) says he would not chose it and I agree with him. It has 6 k ohm resistor. 2 k ohm is in the spark plug boot. So 8 k ohm together which is 400% of a designed value for my car. Maybe this is not a problem at all, but how should i know? I checked on online catalog by Mercedes itself and the dealer made a mistake, because the catalog recommends F8DC4 like nhzruthless818 says. So this is clear like a glass; the dealer sold me a wrong plug. Unbelievable. And I am having troubles with my idle ... BTW i do not believe the wrong plug is really the only problem but anyway ...

2) I ordered Bosch F8DC4 - copper electrode. this plug is also recommended by mercedes because original one F9DC0 (by Bosch) is not produced any more for several years.

3) I did not go for NGK only because there is too much inconsistency in data which are available to me (internet and catalogs at differents car shops). More precisely; one could take BCP4ES, BCP5ES or BCP6ES which is really too much deviation. This is simply not serious.

 

[nhzruthless818]

I have replaced 88 500sl spark plugs for a family friend original plugs with 170,000miles and they were F8DC4. My friend's dad owns a shop and a 99 e420 and i replaced his spark plugs while changing his oilers and factory plugs were F8DC4 (58,000miles only). So in conclusion 88-99 m119s had F8DC4 from factory. My 97 also had them and i have seen some 93-96 they all had them (if i see a m119 in a junkyard and pull the plugs to see what they have)

 

[nathanD.rector]

because of my nitrous,I have to run either Bosch 3 ground,or I now run Denso 5061.I can't chance a missfire.The engine loves them.

 

[nhzruthless818]

because of my nitrous,I have to run either Bosch 3 ground,or I now run Denso 5061.I can't chance a missfire.The engine loves them.

Going off topic a bit here. I always wanted to ask this question. Is nitrous safe on these engines? I remember my old neighbor(i was young at the time) was a chevy guy that had a rusty nova which he restored and threw a ls1 engine in it in place of the straight six. And he setup a nitrous system and after one drag race he had bent rods and valves.

 

[nathanD.rector]

nitrous is safe for any stock engine as longs as you follow the rules,don't exceed 50% of your horse power on a stock motor.If you replace rods pistons,and crank, the sky is the limit.run a cooler plug for each 150hp you add,and retard timing 2 degrees

 

[Melb140]

I did not go for NGK only because there is too much inconsistency in data which are available to me (internet and catalogs at differents car shops). More precisely; one could take BCP4ES, BCP5ES or BCP6ES which is really too much deviation. This is simply not serious.

When I use the NGK search (http://www.ngkpartfinder.co.uk/car_commercial_extra.php?id=14604) I only find one suitable type, all with the same gap:

 

[Melb140]

The original plug:

 

[daidnik]

I've been using NGK Iridiums in old MB W108, W115; later M119's; M112 all with great results. I recently changed my wife's Passat 1.8t AWM to NGK Laser Iridium from the mfr recommended Bosch DPP double platinums and the Laser Iridiums are far better IMO. I will never use a Bosch DPP again.

The matter of the value of series resistance to the plug is not a very sensitive matter as the current is so low. You only need all the plugs to be the same.

Laser Iridium has precious metal on both electrode and ground. It is not available in all sizes, but where it is available, I use them.

Iridiums are better than platinums and Bosch, for whatever reasons were behind the curve on that.

There are often many semi-political factors behind mfr recommendations.

Iridium is most resistant to electrical erosion and thus can be made with the best geometry to generate ignition plasma consistently under all conditions. I have found this to be true for both the old & newer applications. I really felt cheated on the Passat after following the mfr rec's for the Bosch DPP's and then later disregarding them and getting better results with the Laser Iridiums.

My opinion is that Bosch is just plain behind NGK on plugs and has been so for a long time.

 

[1994v12]

run the hotter plug, and try to run a non-resistor plug as well.
I run the Bosch non-resistor plug in my 1994 and it was day/night compared to a Champion resistor plug replacement. NGK is a good plug, IF you can find them non-resistor.