[supersport6]

Help, I want to find a plug that works in my 420 SEL, I just installed a new set of Bosch super WR8DCW plugs and the car ran fine for a day or so. I went to run it this morning and it was shaking like a bag of crap and wouldn't even drive off. I pulled the plugs and they were black, one of them was completely dead, no spark at all. I put in one of my old plugs, cleaned the others and it now runs fine. The temp here is cold, in the teens at night and I don't know if these temps need another temp range of plug or not. Advice is appreciated.
Rod...[]

 

[jdc1244]

Don’t use the resistor plugs. Use Bosch W8DCO.

 

[jhodg5ck]

JDC is correct.. Don't mess w/ the plugs on these cars, run what the factory recomends.


Jonathan

 

[supersport6]

Thanks for the info, I agree and today I ordered a set of W8DC0 plugs, hope these do the trick.......[^]

 

[supersport6]

Fitted my new original spec spark plugs and the car runs as good as new, no stumbling or rough idle and it runs smooth and strong, I just hope it stays this way...[]

 

[John in VA]

Earlier posts suggested Bosch H9DCO plugs...

" gap them to .032� or .8 mm – 28nm torque. This is the same value for all 126 V8s and the M103. "

What is the difference, besides heat range?