I purchased my 2007 MCS in fall 2010 with 12k miles on it. It now has 35k miles and what i believe are it's original spark plugs. Here is a shot of one of the plugs i just pulled from the engine, and would you all say everything looks good?

yes i have knocking issues, usually running 91 octane gas, lots of carbon buildup at the exhaust tips...

 

That plug looks fine. You want a nice brown color on the plug. White and fluffy, you're running lean...black and you're running rich. I believe these plugs have an iridium electrode and sometimes it's tough to tell whether the electrode has worn any...the only way you'd know is to know what the stock gap is (I don't) and check where you are with a feeler gauge. Personally, anything over the stock gap, either re-gap the plug or change them. Also...I think you mean carbon build-up on the intake valves, not exhaust.

 

I replaced mine at about 40K miles and found one of them with a portion of the white insulator missing. I assume it left through the exhaust without damaging anything as the car still runs great and doesn't use oil. I have read of other folks that have had these types of plug insulator failures that didn't end so well. I'm not sure but I think the change interval on the "S" is 60K miles not 100K miles. The original NGK iridium tipped plugs can be purchased for about $12 ea at Amazon.com, http://www.amazon.com/NGK-ILZKBR7A-8...2007&carId=001

 

thanks for replies. I did mean exhaust tips (at bumper) not valves. - my exhaust has a thick buildup of carbon on them. trying to keep them clean is impossible.

 

Plugs look fine and the black soot at exhaust tips is normal for these
direct injection engines. Futile to try and keep them clean.

 

Looking good!

 

If your worried about carbon build up try a light sea foam treatment or look in the direction of you A/F ratio. thick build up on your bumper sounds like you might not be burning fuel right.

 

I don't think he was referring to carbon on the bumper... just on the chrome exhaust extensions. As mentioned above, that's pretty much normal, and my personal theory is that it's caused by the intentionally enriched mixture on startup.

Spridget

 

I really need to get new plugs. I think I am going to go with the JCW cooler plugs.

 

Try wheel cleaner on the tips. I used it when I had mine worked pretty good. I used the Meguier's Hot Rims cleaner. Just make sure the tips are cold just like when doing the wheels.

They get dirty again but makes cleaning easier.

 

I have a quick question.... I recently replaced my NGK Iridium plugs with Bosch Platinum +4 plugs and when I listen to the radio when driving I have what I can best describe as a high resistance noise that increases and decrease when throttling up to idle. Why would this be a result of changing out the plugs?
Thanks,
Mark

 

The plugs may not have the necessary resistor in them to prevent radio interference. Just my two cents.

 

How would I know if they have the proper resistor?

 

The JCW spark plugs, are NOT a cooler heat range spark plug, they are exactly the same heat range: heat range 7.

The letter "R" denotes resistor, you have obviously purchased spark plugs without the letter "R" in the reference part number, this is why you have radio interference noise!