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Idle A/F Ratio ?

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Old 12-31-01, 10:32 AM
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Question Idle A/F Ratio ?

What A/F ratio (voltage) should be seen at idle?

Mine is currently in the .89-.91 range and it seems to be running rather rich. The exhaust stinks like fuel and the car stubles a bit. I just put a new motor in and when I fired it up I had to pull some fuel out using the PFC to get it to idle anywhere near decent since the A/F was around .98.

now I have it idling fairly well but it still seems a bit rich to me.

'93 RX-7
Mods are:
Street ported motor
Power FC
Bosch fuel pump
550 primary 1300 seconary injectors
N-Tech DP
Mid Pipe
N1 Dual cat back
No emissions stuff
Simplified turbo control system

Once the engine is broken in it's going to the dyno, but untill then i would like to get the idle situation worked out.
Old 01-10-02, 11:59 AM
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Sounds like you are not in closed loop yet. Is this with the car fully warmed up? Your O2 should cycle between .300-.900 V. If it's sticking around the .900+ range it is rich and is not in closed loop. Is it a new O2? If not did the old motor put coolant through the exhaust? If so this will destroy the O2, and you should buy a new O2. Or you have got ignition issues.
Old 01-10-02, 01:34 PM
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they dont run in closed loop at idle, because the air pump throws off the reading, from the o2 sensor. you should be ignoring the af meter at idle

mike
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