Hey guys, I just pulled the plugs off my 90 GXL. The plugs have about 35000 miles on it. This is what it looks like. The plug is overall tanish. It has some tannish residue on it. Is that normal or is something not right?

 

Sounds about right

But if there is a "lot" of tan residue you might want to look at what gas (or gas additive) you are using, as there may be high loads of phosphorus in it, which will lead to clogged o2 and cats.

 

You got 35,000 out of your plugs? Thats good. On my street car I would normally change them at 15,000 miles. The car would start easier and run better afterwards. Only used NGK. I would suggest just replacing them no matter what they look like as well as the plug wires.

 

ICEMARKS reply caught my eye. I pulled and changed the Turbo's plugs last week. They were tan, but had what could be best described as little tiny beads attached to the plug. Phosphorous???? I don't use any additonal additives such as fuel injector cleaner etc. You mean additives that are mixed in the refinery???????? As in maybe changing the place I get my gas???

 

is your plug white?!
those bits usualyl mean u are running lean!

 

Should I try to run a higher octane gas? I run a bottle of redline fuel system cleaner or the Heet stuff on hte car. Nothing else. Should I stop using it? And shouild I try to run 93 instead of 87

As for hte plusg thing, well 35000 is not a lot. Consider my last plug change was in April. Yes I did drive that much in 1 year.

Also i noticed on the electro, the one on the leading side is 2x shorter than the trailing one. So I wonder if the leading side fire 2x as much as the trailing ones?

 

104 Octane Boost and things like that are the most common additive to cause that. Although Gas high in MTBE (an oxidating agent for lowering emissions) can sometimes look that way if the timing/burn cycle is off.

Could also be a high sulfer mix in the gas as well. You might try changing gas stations, and see if it changes.

I wouldn't be largly concerned unless it is peeling off of the plugs and/or covering the center insulator.

 

Well darn, running a bit lean maybe. Well I've got my Lead Engeneer working on making a wide band o2 sensor meter. I'll be able to monitor for accuracy in a couple of weeks. Til then I"ll ease off a little more. Use to see those deposits on a E-Type I had a long time ago. Had lead deposits then. This looks similar.

 

Actually, its the other way around. The trailing fires twice as much as the leading.

 

If thats the case, how come the electro on the leading is 2x as short?

 

35000mi wow... i just change mine every or at the least every other oil change.... so 5000-5000 mi at the most on a set of plugs. i use either stock NGKs or Platinum depending on which they have in stock... i'm sure you don't have to change them as often, but if you pull the plugs out, might as well clean them off with the brake dust cleaner... it also makes it easier to check for damages to the plug.. but then again i dont know much about workin on cars so my words don't hold too much weight, only thing i know how to do is drive, change oil & plugs... neways, i just wanted to throw that in there.

 

Changing the spark plug is a bitch on cars that are loaded with options. All those damn lines are in the way

 

Actually tmak26b is right - the leadings fire twice as often.



-Ted

 

Are those "beads" metallic???&nbsp Or are they just deposits?&nbsp Just pull them off and see if you can crush them.&nbsp If they are metallic beads, this is a sure sign of detonation!



-Ted

 

Whoops, my mistake.

 

I remember looking at NGK plugs and there were three kinds: cold, colder, and even colder... which would be best?

 

Mazda recommendation is BUR7EQ for leadings and BUR9EQ for trailings; MOST FC's (turbo and NA) can run all BUR9EQ for all 4 plugs.&nbsp Unless you're doing very major stop&go driving in the city, you can get away with four "9's".



-Ted

 

I get the same on my plugs, fairly easily removed with a wire brush. I'de also be curious to know what they are. I suspect I might have a timing problem as I was out under the hood last week checking up on things and noticed that if I held the throttle open a little bit, the timing would advance as normal, but once in a while it would jump back to almost the idle position for one spark then back to advance the next; ie retarding about 15deg or so.

BTW - I always use Chevron 92, what do you use?

Henrik
87TII