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Left hand bank running rich?

2K views 5 replies 4 participants last post by  AU XR8 
#1 ·
Replaced all spark plugs earlier this morning. Four drivers side plugs were light grey, but the four plugs that came off the pasenger side were black. Does this mean that the passenger side bank of cylinders are running rich? can this be possible?
I thought the fuel delivery was all one system, ie: one fuel rail for all eight injectors.
 
#2 ·
It's the one fuel rail, however you have an oxy sensor for each bank. Possible one sensor is buggered, but at $150, don't go ripping it out on my advice.
 
#4 ·
psycho chicken said:
It's the one fuel rail, however you have an oxy sensor for each bank. Possible one sensor is buggered, but at $150, don't go ripping it out on my advice.
If it's one fuel rail for all 8 injectors, how can one buggered O2 sensor make it's bank run rich? Sorry I'm not disagreeing with you, just looking for more info.
 
#5 ·
I'd say the left O2 sensor is giving a lean signal, so the ECU ups the output for the left bank.
 
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