NA Spark Plugs

[capnsavem]

for a guy that doesnt know dick about plugs, which one of these is bad? good?

thanks flat black!

Take your current plugs out; What do they look like? =) Are they black, and powdery? Whitish? Or a nice, light tan?

 

[flat_black]

Black is too rich, and you'll need to get the mixture leaned out slightly, be it by plugs or EMS.

White or very light is too lean, and you need a slightly richer mixture, again, either by adjusting your fuel pressure or ECU, or by changing said plugs.

You want a range from light tan to a medium brown... Light tan may be a bit too lean for a turbo car, but for N/A, that's a suitable target.

There's lots of data out there on reading plugs, and whatnot. Here's one particular page:

http://www.nightrider.com/biketech/spkplghnbook.htm

 

[capnsavem]

i nominate flat black for official "engine tech mod"

 

[twilightprotege]

best spark plug testing page i've found :

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

 

[flat_black]

Excellent, thanks Andrew. =) That's the page I was looking for.

 

[twilightprotege]

everyone must bookmark that page. that's an order!

 

[Gen1GT]

Now, you shouldn't just pull your plugs at any ol' time to check them. You have to do a full on WOT run to 100mph(or as fast as you can get), then immediately cut the ignition and roll to a stop. This way, you see exactly how your plugs look at WOT, since A/F ratios will run lean during a coastdown with the engine on.

 

[damaster]

I know this is likely an over-simplification of the matter, but I gotta ask: you run the car at wide-open throttle from 0-100 mph, kill the engine, roll to a stop, let the car cool down and "read" the plugs.

White = plug too cold -> E.g. Need to go from NGK heat range 6 to a heat range 5.
Black = plug too hot -> E.g. Need to go from NGK heat range 5 to a heat range 6.
Tanned = just right heat range.

Is the above correct?

I'm running a heat range 6, and when I was doing my oil change recently, I took out the plugs to check them and they were kinda white. I didn't do the 0-100mph WOT test, but thought the reading might be worthwhile nonetheless.

 

[douglas218hk]

i run ngk v power, they run pretty rich... when i put them in the first week the tip was black a bit. now its still black a bit, after 2k miles i think. ya anyone know how to lean it out?

yes, I also have a black spark plug(denso IK20) before, they make my engine run pretty rich too.
now, I have installed a S-AFC to lean it out.