JSK333

Is it possible to "clean" a plug instead of replacing it?

When is a plug "done"?

Just curious if I really need new plugs after only a few thousand miles (Autolite 104s), or if they could be cleaned off somehow. I'm thinking they were "fouled" by some failing fuel injectors, and then carboned-up O2 sensors.

I know how cheap they are, but I am looking more for an understanding of what makes them "not work" and whether it can be fixed or not.

What does it mean exactly when they "foul"? And is it reversable?

Thanks for the schooling.

'94 Bad A Z28

Wow, you're "worse" than me when I'm at "work" trying to explain something to someone on the computer, lol. I "quote" everything like that, lol... that's awesome!

chasmanz28

i go by the color of the plug, to see how the engine is running, if its white on the tips its running lean, black is rich, brown is the color your looking for, if your o2's have over 65k on them ide change them, most running rich problems are because of them going bad, and spark plugs are cheap as you mentioned, ide change them rather than trying to clean them, look at it this way, the plugs are a PITA to change so why would you put used ones in

JSK333

"Thanks."

So does anyone know what causes them to foul? And if it is reversable once they're out of the head?

I'm familiar with reading them according to color, and whether there are deposits... I'm curious when they actually need replaced, what causes that.

Solomon

Injuneer

The black soot can be from running rich at idle and low loads, or from burning oil. The colder the plug, the more likely a rich mixture will carbon up the plug.

I remember 40 years ago when it was very common to clean plugs in a special machine that was basically a sand blaster, with very fine grit in it. I haven't seen one of those machines since I sold my parents home off 10 years ago.

With a modern EFI setup, running in closed loop, there is absolutely no reason a properly tuned engine should foul the plugs..... with a carb, yes... there will always be "good" points and "bad" points in the setup, causing fouling at idle or under low loads, but with EFI, the plugs should never load up.

JSK333

Thanks Fred,

So say for example when my fuel injectors went out, that the plugs fouled. Will they become "unfouled" once I put new injectors in and ran for awhile?

Or are they permanently fouled?

Injuneer

My experience with "fouled" plugs goes back to the 60's, and my 63 Impala with an AFB 4-bbl carb on a 300HP 327ci small block. If you got stuck in a lot of traffic, or drove it like an old lady, the plugs carboned up. The solution, if you caught it in time, was to take it and rev the pi$$ out of it until the plugs cleared up... but if you let it go too far, you couldn't "reverse" the process.

I had some fouling with the stroker, but that was when the computer was progammed to run alpha-N.... looking only at the throttle position and rpm. Ran a little rich at low load in traffic, and the plugs (more than 3 step colder than stock) looked like charcoal briquettes if you didn't make a few max power passes from time to time.