Ok im trying to figure out if my car is running lean, which i think it is. Here are the spark plugs i just took out. I know tan means lean but im not sure if there is supposed to be NO tan at all or if a little is ok. Well here they are, and i know some of you can tell a lot just by looking at the spark plugs, so please let me know. Lean, rich (i doubt it), or OK?

Leading plug front rotor: The tan circle you see looks like just clean metal rather than a tan-colored buildup.



Leading plug rear rotor: This one has lots of tan-colored buildup on it, with a little black.



Trailing plug front rotor: lots of black buildup with a little tan.



Trailing plug rear rotor: mostly black with a little tan.





so what SHOULD they look like? Does anyone know why the leading front is so clean, with no build-up on it?
Again, i just mainly want to know if im running too lean.

Thanks,
Greg

 

looks like the leading plugs are carboned up.thats usually from starting the and not leting the car warm up fully.Usually if you do a lot of city driving you usually want a hotter plug do to the changing temp of the engine.If you do alot of highway driving you want a colder plug, because the engine is at one steady temp.

 

Yeah i admit i do drive it before it is completely warmed up, but i never let it get over 3k and never boost until its warm. Should i not drive it at all until its warm? and can you tell if im lean by looking at this?

 

if im correct i think carbon build up is from running too rich and not all the fuel being burned up in the combustion chamber

 

That is correct but I also know that if the spark plugs are tan that is supposed to indicate that its running lean. I just dont know how much tan is too much or if you are supposed to have any.

 

How did you run the car before you checked the plugs? What you should do is give the car a spirited drive with lots of high revs, shut the car down with little or no idling, then remove the plugs being careful to not burn the crap out of your hands. If the center insulator is a rich tan color, you're good to go. Ignore the black or tan buildup on the metal parts 'cause it has no effect on effective spark.

If the center insulator is black your air-fuel-oil mixture is too rich or there is some sort of electrical problem that is preventing a strong spark. Could be a cold heat range plug, or a faulty ignition system component including the plug, plug wires, coil/ignitor, or possibly another component. If the center insulator is white (assuming this is not a fairly new plug), things are getting too hot at the plug. Either you have an excessivly hot heat range spark plug or there is a very lean A/F mixture in that region of the combustion chamber.

 

Looks about normal for plugs with 10,000 miles of mostly city driving.

 

Those look good to me, maybe fuel additive has caused the buildup but not bad. At least they not black or wet looking.

 

Thanks for the feedback guys. I am worried about running rich, i am actually afraid i was running lean. I would have said that before, but i didnt want my suspicions to sway your responses. Here is the problem i am trying to diagnose.
https://www.rx7club.com/showthread.p...hlight=leaning

^cliffs notes: engine hesitating at 6500 rpm under WOT, i wasnt sure if it was lean or maybe hitting fuel cut.

Thanks again, and more help and opinions are welcome.

 

Except for the top picture, the rest of the spark plugs (pics) all look normal.
The top picture looks like it's running slightly rich.
None of the plugs look like it's running lean.

BTW, are you running Chevron gas?
Gasoline with heavy additive packages leave those heavy tan deposits.


-Ted