do i need hotter plugs?
 

Well, i just pulled my plugs, they're kinda black.
Do i need hotter plugs?
or just cut the fueling back?

i dont know how long these have been in... never asked the previous owner.

they were the ngk's that are 1 step colder (7's)

http://www.neonshaun.com/miata/plugs.JPG

Hard thing to see in the pic, but the electrode looks good. I'm more concerned with the rust on the top of the plug than anything else.

What's your system?

Well I would definately put new plugs in, who knows how long those have been in and how different its ran over the years. Put new ones in run it for a lil while then pull them.

Someone recently told me the best way to check the plugs was to put new ones in, drive the car for 20 minutes and then cut it off and coast home (because of ecu fuel cut off and stuff with idle, etc). I have not tested this.

BTW, I'd swap plug wires too. Good plugs will tell you a lot but I am not sure what a bad wire will do (might make it overly rich and black like yours). Spend the $50 for wires and keep the other set as a backup for testing if you don't see any problems.

bad wire = not good powah to plug = might miss-fire = icky plug

the electroid you can see has a nice copper color, which is good. Could be a tad rich from the rest of the carbon. they need to be replaced. and gapped properly.

the best trick for reading plugs is cutting the engine at high rpms after a boost run....that way when you pull it to read you see exactly what they look like just under boost....not after they've been driven on and the carbon has built back up.

i put some plugs in.. 3922's gapped at .33

seem to be working fine :)

now since you don't have a wideband obviously. listen closely for ping, watch your oil gauge in boost. It will sorta freak out if you are pinging.

try to pulling plugs method...if you cut the engine at 7k while WOT and coast to the side of the road you can read what your plugs look like.

or if you list your setup we can pretty much tell you where you may stand.

my miaaaaaata:

it has a base greddy turbo kit,
intercooled, 440 RC injectors, fm link ECU kit (with the boost control
solenoid, and knock sensor) AEM wideband, ACT clutch/pressureplate,
bosch BOV with check valve, torsen from a 1.8l, and Some Custom
DP/exhaust with a flex fitting and 2.5/3" pipes...

it's been making a buzzing/rattling noise lately when i let off the gas at high rpm's and coast down in gear. It also seems to do it when i push the throttle a little bit under 2k rpms.... hmm

i hope its just a heatshield...