Is it normal for the leading plugs to be this fouled after a few hundred miles on new plugs? Since the car is no longer passing inspection I guess not Anybody have an idea what might cause this? The trailing plugs seem to be slightly drier than the leading. Could there be something wrong with the leading ignition coil? The front and rear leading plugs share the same coil. That would explain why front and rear leading look equally bad. If there were a bad wire or injector I would expect just one of the plugs to be bad. If it were a fuel map problem (I have PowerFC), then I would expect all the plugs to be similarly fouled. Any other ideas?

-Lloyd

 

I don't know if this will help you or not but I have had similar issue where my plugs weren't so clean at low mileage (especially one):

https://www.rx7club.com/showthread.p...ght=spark+plug

So I wouldn't be surprised if that was a rotary feature (running rich plus oil injection can't be good for plugs...).

 

Do you know which plugs are which in your photo? I would be interested to know if the leading plugs were dirtier than the trailing.

 

The two outer ones are the trailing plugs when the two center ones are the leading plugs (on the first picture in the link - sorry I can't find the pics otherwise I would have them re-posted).

I am still not sure why the one got badly dirty (oil injection or injectors that have issues?.?.?).

I should check them in 2000miles or earlier and see. Hope it helps.