Mechanics

COULD I HAVE AN INJECTOR PROBLEM?

2001 Mazda Millenia • 15,500 miles

The engine codes read P0140 and P0303.
I have already replaced the plugs, wires, distributor and rotor. Additionally all the back plugs are black (1, 3 & 5 with #3 the worst). The engine runs rough and has a definite backfire. Could this possibly be an injector? Or could the o2 sensor cause such an obvious misfire?
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Poppabrand
January 15, 2012.




Rear cylinder bank is running rich apparently.

Tiny
Fixitmr
Jan 15, 2012.


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