"Trying to read plugs on a modern car that runs unleaded to determine if you are a litlte lean is tough. The fuels all stain the plus differently due to the additives"

A member of the board in another thread posted this statement up and I wanted to get some more input and see what others thought. Not saying I dont believe him just wanted to see other opinoins on this. I posted up that I thought I was running lean because my plugs are as white as the day I put them in. I have only been cruising and no WOT blasts. I always understood that you want you plugs to be tan in color to show a good fuel and air combo (i.e. stoich) therefore I thought I was running lean.

 

If there is no apparent glazing of the plugs which produces a shiny look around the top of the porcelin and can also take on a yellow tinge and there aren't any purply ***** stuck to the porcelin when viewed under magnification then you should be happy. Your engine is.

 

The porcelain is not where to look to read plugs.
Ya need to look at the metal threaded part on the end and the ground strap. Way down inside,at the bottom of the porcelain it will make a ring but buy the time it does that ya will have holes in the piston if it's too lean.

Might Google the subject as there are some good tech articles on the subject.

 

You can have the wrong heat range plug and think you're too rich or lean. That ring on the insulator can tell you heat range and they typically cut open the plugs with a diamond saw to look at it after running plugs with a thermocouple to see how hot it's getting. There's certain temps where it will burn off the carbon up to a point and if you're not in that range, it will eventually foul no matter how great your ignition is. You dont want to see little cracks in the porrcelain insulator or little ***** of molten aluminum, cause then you ARE in trouble with too lean or too hot a plug. If you want to read a plug you can put a brand new one in, do a blast on the dyno or track and immediately shut it down and look at the thing with a magnifying glass and that's the closest you will get to seeing if you have the right mixture or other problems. You got a car with a centrifugal blower and 90% of the time you're driving around like grandma and other times you're blasting down the road like a house-a-fire with 10# of boost and 600 hp, you might have to compromise towards a colder plug to be safe. And get a wide band sensor setup, now that they're cheap. How anyone can tell anything without one of those is beyond me. EGT's, too. Good tuning tools. Use the coldest heat range that doesn't foul and dial your mixture with a wideband, EGTs or both.

 

Been reading plugs since the '50's with no A/F meter with no problems.
The A/F meter makes it IDIOT proof and no learning curve as to HOW to read the plugs without hurting something.
If ya got an 871 on a SBC ya better know what ya are doing when ya pulley it down or it won't make it the first 1/8th mile.

Good tools but not totally necessary.

 

Man, yer old.

 

Yep, when I was your age,I would have bet I wouldn't survive to be this old.

Some days I feel 10 days older than dirt.

 

And I was just kidding ya, too - but glad ya got a good sense of humor since everybody's pretty friendly around here.

If I remember right, Wicked 95Z's original post was about his new blower engine - street car - just pullied up and maybe running lean in cruising around (closed loop) and he's concerned about it.

Maybe he can take a high res close-up of the plugs in question and post it and you can offer up an opinion on the state of things.

I can tell you for a fact that those pictures in the spark plug catalog that show how to read plugs haven't changed probably since the days of leaded fuel - they were a lot easier to read in those days - now I'm dating myself. I just have seen unleaded deposits look all kinds of ways, besides the obvious stuff of oil & carbon fouling, signs of det, overheating & such. His main problem might turn out to be making too much power in closed loop and the pcm keeping him at 14.7. We were wondering if it would help to lower his % of Throttle for WOT (enrichment), especially if he has a larger throttle body and then tune it from there with the PE tables - otherwise, maybe an aftermarket management to get it where he wants.

 

Ya think unlead is tough try alcohol where it will take a season to get any color.
That might work for him. I have one of the best guys in the country to read and tune so I don't bother with it much as far as computer tune goes. I leave it up to him(even though he is a Ford man)

Might be able to tell something from the pictures.

 

Ill try to snap a picture of the pulgs. I do have a 58mm TB. I thought about running a PE idle back when the car was n/a but never could get it to work just right and then I got the blower and I figured I didnt need it because I didnt have a tight LSA on my cam. I guess a wideband would be the best way to tell

 

wicked_95z, may I post some pictures too?

I don't want to hijack your thread but I just pulled my LT1 plugs and since the thread is here and getting attention from people who know their way, I'd like to get a diagnosis.

 

When Second Street tuned my engine for the 300-shot on an engine dyno, they would put in a fresh set of plugs for each pull, make the pull and immediately shut the engine down. Then they would pull all 8 plugs, and examine them with a plug viewer with a bright light and a magnifying glass built in. Then they'd put in a new set of plugs and start all over again.

I asked them to show me what they were looking at, and I couldn't see much of what they were telling me they could see on the center electrode porcelain. Given the engine is still in one piece 6 years later, I guess they knew what they were doing.

There's no substitute for experience.

 

rock on man

 

Thanks!
I have one plug from the passenger side closest to the firewall (#8 ?) which has desposits. I found a web page that describes plug conditions with pictures. My #8 plug is a match for one of three conditions. I want to show them to hear the experience of the experienced. Here goes:

all 8 as they came out of the car. I think they're OEM @ 100k miles.

the fuzzy one to which I got too close with the camera


This lone plug was completely loose when I put the wrench on it. Notice the blackened porcelain. The car had a slight roughness at idle from when it was purchased @ 96k miles. The car absolutely screams otherwise imho. With new plugs the slight roughness is the same or slightly less. But if those deposits are from a leaking head gasket, rings or valve; I need to know what to do next....

thanks

 

The car now has nitrous injection. I have switched to NGK 4177 (TR6). Actually only 7 are NGK. I broke one plug trying to get the socket off and bought the only cross referenced plug at the local NAPA. It is an Autolite 103. I plan on changing it to an NGK when I visit Summit. If the #8 cylinder is bad, I should probably forget about spraying. I'm hoping someone gives advice on what to do or try. Thanks