The car is completely stock. I just replaced the plugs and oil, and the plugs are half white and half black on each plug. Any ideas. The car runs fine.

 

The car is most likely running rich in one range as idle ,then at speed the mixture is fine , rich will black the plug then the heat from the correct mixture cleanes the center of the plug . if I am correct the black is on the outter ring and the center is white. Am I correct ??

 

just like he said sometimes rich sometimes lean, find out when its lean, at idle thats fine, thoguh fds run rich at idle, make sure u are not leaning out on teh top end

 

the question is..which plug? leading or trailing?

The leadings should be uniform in color. At least a brown/tan. Are your plugs really half black/half white? no tan/brown?

I'd be fearful of some lean running. If your leadings are half white, i'd be concerned. My plugs were all black for leading and half black and half brown for trailing

Danny

 

I'm dead serious, half black and half white on all four plugs, could it be a clogged fuel filter or leaky injector? I'm at 124,000 miles. Would a bad fuel pulsation dampner make you run lean?

 

if you dotn remember the last time u replaced teh fuel filter DO IT NOW. the bottom plugs shoudl be all dark what boosta re u running and what mods

 

yup, bottom plugs SHOULD be black/brown. Change the fuel filter and clean the injectors. I mean CLEAN like go to rc engineering or osmething.

Danny

 

yes , I Own A 1999 Mitsu Mirage ,4G15 Engine 1.5LTr Auto.. Whenever I Take The Spark Plug Out, It’s Ring Is Black And Electrode Reddish Brown..

what Is The Way Forward.. Any Solutions

New Spark Plug After 3000miles

 

Do you realize that you are on a Mazda RX7 forum? This is not the place to ask about Mitsus...