Plug colour concerns
Hi, I changed my spark plugs today. On removing the old ones that were NGK pfr7b`s that had covered about 20Km I noticed that all of them were very dark in colour (near enough black) especially the two from the drivers side of the engine ( 3 & 4 iirc ). Gapped to 0.7mm
Is this someting I should start to worry about? Car details - MY95 WRX - K&N Induction + Full Decat + ScoobyECU + Vta D/V + run on Optimax or Tesco 99 + Sti Fuel Pump + Motul full syn 10w40. Thanks Paul |
i think a dark plug means its running rich, dark as in covered in fluffy carbonish type stuff.not black with oil which means kanckered valves seals,pistonrings etc..
plug should be a nice tan type colour when running proper. might be wrong, just talking from experience with other engines. im yet to pull out my plugs in the scoob and have a look. Rich |
fluffy carbonish type stuff.
Thats the stuff, its not oiley at all. So does that mean I`m running rich on no 3 & 4 cylinders more than 1 & 2 then, if so is this better than running lean or just as bad. |
what was the plugs on 1&2 like? running rich isnt as bad as lean, lean leads to very high temps on a turbo car, and can melt pistons, u prob know that tho. running rich is not as bad but should be sorted.
if u was rich on all 4 cyls then id suggest that ur map is off and could cope with a bit more boost to use up that extra fuel.... just 2 might suggest an injector service or replacement.. can anyone back me up? Rich |
The state of the plugs can depend to a certain extent on how the car was last used. If you started up from cold to move it or drove a short distance without full operating temps, then the plugs could give a false rich appearance as excess fuel would have been injected, especially in the current cold conditions.
Some maps can also richen No.3 as that's the 'hot' one. |
All the plugs were a dark brown/black colour, but 3 & 4 were defo. the darker pair.
Running a ScoobyECU map on a Z4 boosting to around 1.1bar. Would I see a benefit from fitted a MBC (dawes device) Houghton - I did drive a couple of miles to pick up the plugs and I changed them as soon as got back, so would this have given the plugs a richer colour. |
Originally Posted by MadDogWRX
Houghton - I did drive a couple of miles to pick up the plugs and I changed them as soon as got back, so would this have given the plugs a richer colour.
Don't know much about your ecu but on some, cylinders can be individually set for mixture. |
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