A/F/R gauge for tuning

sensor read rich on a lean mis fire, you asked me to explain way back but i'm in a different timezone.

I can't becasue i don't know why.....

my senser is at the end of the collectors so i can't see individual cylinders just the average of the lot therfore 1 or more with a problemn can skew the reading.

i had presumed it was either to do with the temperature of the sensor or ratio of unburned fuel to air in the exhaust gas being so wildly out of normal that the sensor wasn't doing its job anymore. the thing is heated, but i have no idea what a blast of unburned mixture does to that.. i.e does it work properly when its operating in an adverse situation. they were designed for FI cars that would in theory, never be so badly wrong as you can go with a carb

Or

as you drive through the misfire the sudden pickup of all cylinders again or backfire through exhaust starts a flow profile through the carb that causes an instantaneous rich condition. its a carb a big dumb thing that reacts to a pressure difference.

tuning on the street gives less oportunity to hold rpm and analyse. so what you see is
scattered lean rich for a split second followed by rich.

and this is what i see.

i'm working with weber DCOEs that meter on vacuum pulses in a similar way to a holley...But its port on port induction so there is no plenum to smooth out the pressure waves seen at the venturi in the carb, and no plenum of volume to act as a reserve supply of pre mixed fuel and air.
i basically have 6 carburetors on 6 tuned length inlets to worry about


i've never owned a holley-like carb so can only speak from what ive done and what ive seen with what i have .

and i will get rich readings in some cases, where the only fix for the problem was bigger jets implying it was lean. That invariably leads to some air jet work, bigger, so that its then not rich higher in the rpm range, but that bigger air corrector causes the mains to come in earlier making it rich in transition..... and on and on and on....

on a dyno you will have greater control over the situation and more time to work out whats going on, what you can see may well differ from what i am thinking i see becasue you have a better view.

the OP is more than likley doing what i do...i.e its a hobby and its being done in the driveway
hence probably won't see what you see on a dyno but might see what i see...

Averages are key as you say.
looking at trend before and after the issue, and ignoring the gauge during the issue, would lead you to Lean quicker, than the BS you see on the gauge at the point of the issue. When the sensor is trying to cope with a situation that is off the scale one way or the other.

As i said, these are put to their best use, when the car already runs and drives.


Dave