Slo_crx1

Finally found some good ones here, one's that actually show you what and where to read. Granted these are in n/a cars, but the principles are the same.
Spark plug reading 101...
http://www.dragstuff.com/techarticle...ark-plugs.html

Reading spark plugs...
http://www.dragstuff.com/techarticle...ead-plugs.html

Nitrous plugs and pics (would probably do well for boosted setups too)...
http://www.dragstuff.com/techarticle...-pictures.html

I learned a few interesting things I didn't know about before, mostly due to vague references and pics from other sites, so these are definately worth your time to read. Go ahead and post up your thoughts JD, I think you and a few other select tuners have the most experience at plug reading and how to tell what afr they're sitting at. Hell, might even do good to make these a sticky.

TorganFM

Good stuff like reading ground straps and threaded end.

MAJORAHOLE

so to get good reading do you have to run a new set of plugs each time, or just keep cleaning your plugs after each inspection?

Slo_crx1

You can clean them, but you just have to use a spark plug cleaner to do so. It's basiclt a little sandblasting unit that hooks up to your air compressor and blasts the plugs clean again. Best bet would probably be to try a new set of plugs though.

MAJORAHOLE

tuning could get expensive then. well if you only read plugs, and no wideband

Slo_crx1

That's the thing...get yourself very close with a wideband and one you're there you check your plugs between pulls. As long as you're sitting in that "bake" temp area, your plugs won't be black and sooty like they are from start-ups and low rpm cruising. Then when you look down INSIDE the wells at the base of the porcelain it will tell you how your afr looks for each cylinder, the porcelain will show signs of detonation (peppered with black spots or aluminum), and the ground strap will show how your heat range is sitting.
I pulled my plugs this morning after a hot run to 3rd, turns out that turning my fpr up helped alot...#3 had no more black pepper spots on it (lean detonation I'm guessing) and deep in the wells were a very nice brown color on all 4 plugs. Only issue was the ground strap...the annealing line strected from the tip of the strap almost to the middle, which tells me my plugs are too hot. Put one step colder in and the line moved towards the center where it should be. My setup is pretty much tuned narrow-band for part throttle driving, and plug reading for boost. It can be done but it's a major pita as compared to using a wb.

MAJORAHOLE

did you use the NGK's or a dif brand??
what did you use to look? i have a 30x mag. lense i used to used when i was a "gardener". will that werk?

Slo_crx1

NGK's ftw. Just their standard v-power plug. I have a bore scope with a light and a magnifier built in...I can't really get down in the wells, but I can still see to the bottom. Plus with plugs that are colder ranges the wells aren't as deep. As long as you can get some light down in there and be able to see the wells clearly, I don't see why your magnafier wouldn't work.

dirtygsr94

awsome post thats some very usefull info.