I recently did a spark plug/ wire and coil change on my 98 gt-so 1500 miles later I pulled some plugs to check em. They looked dry but pretty black with a light coating of redish dust-I check some plug charts but nothing matched-the dust rubbed off but the greyish black stayed on plug-I also regapped my plugs to 65 because the coil called for it-any input on this would be great since I'm about to send data to Bama for a retune. Thanks

 

Red seems to indicate the use of a fuel system cleaner.

Black and dry might be a bit rich...not a hot spark.

Wouldn't BAMA inform you as to the needed plug gap based on the tune?

 

Yes I did use octane booster a few times-nice call- Bama didn't specify any gaping only screaming demon did with coil-when I calked Bama they didn't think it would make a difference which I thought was strange-so I'm going to try to do the data log and get some better tunes-I'm testing them tonight with a timer to see what the differences are 0-60-and mud range

 

Do you have any pictures of the plugs? What color is the porcelain? That's what you should be more focused on when reading the plugs.

Bama will be able to take care of any minor adjustments needed, after a datalog. Adding the Screaming Demon coils and new spark gap won't alter the tune very much at all. At that point, Bama will be looking at your tune with a fine tooth comb for mild tweaks, if any.

I'm sure they'll have you squared away, but if you need any other assistance just let me know!

Shane

 

 

Looks like a normal plug. The reddish areas are a bit odd but as stated above probably due to fuel additives. Browns,tans,grey light coatings are fine. Dry black carbon deposits on the exposed to the combustion chamber part at the end of the threads is also normal.

 

Thanks for the help. It's running g decent -always hard starts-takes a lot of revolutions to start-new coils plugs wires-I think may need a fuel filter-

 

I disagree. That porcelain should be lighter in color.


Normal
Combustion deposits are slight and not heavy enough to cause any detrimental effect on engine performance. Note the brown to greyish tan color, and minimal amount of electrode erosion which clearly indicates the plug is in the correct heat range and has been operating in a "healthy" engine.

VS:


Carbon Fouled
Soft, black, sooty deposits easily identify this plug condition. This is most often caused by an over-rich, air/fuel mixture.
Check for a sticking choke, clogged air cleaner, or a carburetor problem - float level high, defective needle or seat, etc.
This may also be attributed to weak ignition voltage, an inoperative preheating system (carburetor intake air), or extremely low cylinder compression.


http://www.verrill.com/moto/sellingg...colorchart.htm

 

The porcelain is grey/brown/red as is the ground electrode.

I would expect plugs that new to look better but they aren't carbon fouled and the electrodes look fine. Least what I am seeing in those photos is not carbon fouling. The carbon on the edges, which I've seen on every plug I've ever pulled out of a 4.6 is normal and forms pretty quickly.

In the first photo the center porcelain looks to be a normal tan/brown in color with some red in it. Within the range of a normal looking plug IMO but darker than the miles would say. In the second photo the brown/red I don't normally see. Yes it is dark, but it's not a color/texture/gloss/thickness that indicates a problem with the engine and probably has more to do with what is being burned in it. Something in the fuel is leaving those brown deposits on the plug.

From what I know and re-verified in a web search is that red, yellow, brown and other colors are due to fuel additives. Be they in the gasoline when purchased or added to it afterwards.

If only one plug showed brown then I would be suspicious of something going on, but if all of them are more or less the same then it's probably something in the fuel that is producing an odd color. In the absence of any codes or other issues I'd blame the fuel additives for the odd color. The black on the end of the threaded portion is entirely normal.

 

Thank you. Very helpful -getting set to do the data log and hoping to get my tune tweaked.