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Ok, how do you adjust for a lean mixture?

4858 Views 8 Replies 4 Participants Last post by  jhodg5ck
See previous thread on adjusting idle....

They said they adjusted for a lean condition, but the idle would increase if they did that... So they reset it back to the lean condition and said it was a bad idle control valve.

I'm fairly competent with cars, but this is new to me.
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jhodg5ck said:
by turning the CO adjusting hex bolt clockwise. It is just in front of your air metering plate. 3 mm hex key..insert, push down till it bottoms, turn in fractions of a flat to adjust.

I would check your voltage @ the air idle valve after adjusting the mixture/CO (btw, this only effects up to 2500 RPM mixture wise).
When was your O2 changed last?

Does the car have a rough idle?

Thanks man, appreciated. No it idles fine, purrs like a kitten. Have no idea when the 02 was last changed. Should I swap them out ya think? Doesn't hurt as far as preventitive maintenance.....

So just take the 4th grey wire and clip it and run it to the ground on the battery, correct?

Also, I can use a sensor from a mustang, right? I might have one of those around--I have 95 Mustang GT, so that should work fine, right (last of the 302 5.0 liter engines.)

How do I tap into the lambda and where is it on a 420 SEL 1991. I found an article talking about the emissions, but couldn't find out where the port is for it.

I'd like to install a wideband, but they are still kind of spendy for a one shot calibration of Air/Fuel ratio. I guess I could run it on a dyno for $60 to get an air/fuel reading... Would that be better than reading the millivolts?

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