Black Soot on One Spark Plug
- Thread starter engind
- Start date
Light black deposits indicate incomplete fuel burn. Heavy gunky deposits indicate oil. Looks like incomplete fuel burn to me.
This could be caused by many things:
- weak/bad plug
- weak/bad coil
- dirty injector not misting the fuel properly
- Weak injector seal allowing fuel to leak through
- low compression (usually this is accompanied by oil gunk deposits)
If it seems to be running OK, don't get too concerned, especially with 180K miles! Run some injector cleaner through a few tanks and check the plug again.
This could be caused by many things:
- weak/bad plug
- weak/bad coil
- dirty injector not misting the fuel properly
- Weak injector seal allowing fuel to leak through
- low compression (usually this is accompanied by oil gunk deposits)
If it seems to be running OK, don't get too concerned, especially with 180K miles! Run some injector cleaner through a few tanks and check the plug again.