Im struggling with this right now as well. I have a dash mounted A/F gauge but it lies to me through the medium of flashy LEDs
If you turn all the accessories in the car off then at idel it shows rich, but if you turn the lights and fans on then it nearly shows lean? is this strain on the engine via the alternator, or is it that the voltage supply to the meter should be regulated at 12v
Im thinking of visiting a tuner to see if they can get my car back nearer where it should be but the only adjustments would be the AFM, throttle bypass valve (idle) and the timing. Would this be enough to set teh car up better than current
(it cant get much worse)
Currently running about 20p per mile! or about 21mpg. I would really prefer 25mpg which would be about 17p per mile or a saving of £372 per year (so I can spend that much making the change and be no worse off. My bluebird turbo (same engine,heavier car, intercooled, more restrictive exhaust) was <14.5p per mile or 29mpg so it should be achievable.