what could be the problem?

I took out my new plugs and saw it was running rich (sooty black) also my lil civic is drinkin gas (22mpg).... I dunno whats wrong. I recently replaced the cap, rotor, ignition coil and plugs. No CELs, tire pressure fine, no dragging brakes.... what could be the problem? to my knowledge the A/F mixture is controlled by the ECU...... what sensors controll it too?

help!

*update* it seems to get good gas mileage this tank... but that means it a speratic problem and I want to fix it before it starts to suck gas again...

 

How long has it been since you used fuel system or injector cleaner?

 

not in a long time... but i didn't think it would decrease my mpg by 10 mpg...

 

A gunked up fuel filter , or a worn out (but not throwing a code) oxygen sensor could cause you to sporadically run rich.

 

For $5 or so, I would give Redline SI-1 a try.

 

Yeah, the Red Line stuff is money.

Let your tank run down, dump the bottle in, then fill er up. After the whole tank is run through the fuel system should be much cleaner. It's possible that the filter wtill still need to be replaced even after the cleaner.

 

where can I buy redline?

 

Pep Boys carries it. You might be able to find it at Kragen, Autozone, etc too.

 

how about BG 44k forumla? thats a lot better.. but harder to find h:

 

so the o2 sensor DOES control a/f mixture?

what else does?