Spark plug color analysis please...

[morebhp]

Guys, I'm having that drivability problem with my '95 MTX. I just put in some new Autolite XPs and thought I'd take the opportunity to post a pic of my old plugs on the forum to get some thoughts on the coloring.

Is that whiteness on the side electrode indicate a bit of a lean mixture? Just wondering.

Thanks.

 

[SHOZ123]

Yes it does, they should be light tan to dark brown ideally.

 

[morebhp]

That's what I thought. I'm going to run a fuel pressure test tomorrow.

 

[1slickRED89]

are they in the order they were in the engine? only thing I would say is that cylinder 4 is misfiring and not getting hot enough to clean the insulator, thats why the cermic insulator is black and the others are white. in order of probability you have a bad plug wire, poor wire connections, then a leaky fuel injector on #4.

on the other five spark plugs, the color and depoists look normal. you might want to change gasoline brands to get rid of the white deposits, but its not a big deal for the spark plug. might be burning a bit of oil too, how many miles on the engine?

 

[morebhp]

I noticed that on the insulator on #4 too. I hope its not an injector problem. Are those difficult to replace? I'm pretty sure the wires are good. They are only a few years old.

The engine has 63K miles on it.

I always use Chevron, Mobil or BP gasoline. I'm not sure how to improve on that.

 

[mclarida]

Put the Motorcraft plugs in it. That is what works-
M

 

[Phoenix]

It's too lean , pull the codes and see if something comes up.

 

[morebhp]

There are never any codes. It must not be lean enough to tip off the ECU.

 

[1slickRED89]

this PDF may be helpful to you. it has the famous color chart with different spark tip conditions.

http://www.power-21.com/HoneywellPo...e/Plugs/HeatRange/9S_Plug_Tips_Tell_Story.pdf

before you get too far into it, I would suggest re-cleaning all the ends with rubbing alcohol and giving them another coat of silicone grease, with a clean set of spark plugs and giving it another try. I'm always surprised how much clean, silicone greased and perfectly routed spark plug wire connections make.

 

[blowby]

After many years of reading plugs from my race cars, I can tell you this.
The ground strap is not an accurate way to tell A/F ratio.

The ground strap will indicate the timing, The white line should appear near the bend, just below is good for economy.
Your plugs all show just a little advanced timing but nothing extreme.

The base ring is a better place to start looking for A/F ratio problems.
you want to see some light black coloring or soot all the way around the base ring. Your plugs all seem to be ok in that area, It's a little hard to tell from your pics though.

I wouldn't worry from what I see here though.

 

[SHOZ123]

When you say base ring just what area are you talking about? The porcelain or the steel shell?