Curious about these, as I am replacing my plugs this weekend. On the Bosch website, it only recommends the Platinum 1 Finewire 6702 or the Iridium OE Finewire 9652. I called Bosch and a technician is going to call me back. Any idea as to why the +4s wouldn't be recommended?

 

from the factory: Platinum +4s are being phased out. Single ground plugs are what will be here to stay, so if you really want +4s, get them now. I asked if there was a technical reason for the discontinuance, and he said that there really wasn't, but that the market is moving more toward an OE type plug.
Others here have said that the +4's added grounds created a hotter spark that could damage the motor. If that is a popular belief (true or not), then that might explain why Bosch is cutting that line.
Now I am worried- should I get some +4s before they are all gone, or should I take the plug's discontinuance as a sign that I should stick with an OE plug?

 

Start hoarding them now and sell later on Ebay?

 

Get them and return them if they don't play well in your Disco. They solved idle and misfire issues for me without any other changes. I put Magnacore 8mm on before I swapped the plugs - added piece of mind, but the plugs are what rocked it.

 

Look, listen to Mike he is like the God of Land Rovers. He is why I put them in my Disco. This thread I started has turned into back alley brawl...Would someone just please answer my question about torquing the plugs?

 

BMW does NOT use Bosch spark plugs and has not since at least 1998! Mercedes I don't know about but I do know that BMW, VW/Audi have always used nothing but NGK plugs since 1998 or 1999. VW/Audi have started running a few single electrode Bosch plugs in the 2.0T but the majority are NGK. Obviously, BMW & VW/Audi ARE NOT the "worlds largest manufacturers" but have shown a dislike of Bosch plugs. Wonder why? The platinum +4 is only the start of the answer. The Germans typically look out for quality not quantity. I have personally seen +4 plugs cause misfires in VW/Audi engines. I also feel that engines that have run them have a higher rate of valve related failure. I have personally seen several 2.0 Volkswagens burn valves running them. I would not risk it. My 2001 Disco runs perfect on the factory Champions. After all, it was the plug designed around the engine, for the engine.

 

Yes, torque the plugs. If they aren't, then they could loosen up. Have you figured out where this mystery noise is coming from?

Being only 20 ft lbs, you should be able to make them snug by hand and be good. Just don't go crazy and strip out the threads in the head. If you don't have a sense of what 20 fl lbs feels like, then break out a torque wrench.

 

Thanks Banzai. No I still have not figured out the mystery noise yet. I honestly think it is leaking from around one of the plugs and I think its number 8. I will torque them all down and see what happens. When I put the new plugs in it ran perfect without the noise. When the engine temp got up to 200 the noise started. It was like that yesterday as well. When the block is cold its quiet but when it heats up I can hear the leak.

 

I would be very interested in seeing some evidence as I run them in my Dodge Dakota 3.7l and its great, my 2001 Mercedes ML320 with great power and my 98 and 99 VW Beetles with marked improvement. I just ordered them for my 03 Disco SE. If they are going to cause a problem I would like to hear more about it. Thanks!

 

If the factory is dropping them, that is usually an important sign. You can bet if they were flying off the shelf and never had returns and no law suits then sales dept would slap a new logo on them and sell them as "improved design" for more money.

Maybe it is the start of a new sales campaign and they will come back stronger than ever. Remember "New Coke"?