What to trust?

[IBLOWN]

Hi all,

My A/F on EfiLive reads 12.00:1 at WOT but i have an autometer A/F ratio gauge that reads 14.0:1

So which one do i trust. Im leaning against trusting EfiLive as its a more direct route to the oxygen sensors where as the gauge is just spliced into the sensors purple wire.

The car has no knock and has never knocked since intercooling it (twinturbo VS V6 commodore) which makes me think the gauge is wrong. Being 14.0:1 with the guage reading under WOT i would have thought it would.

[joecar]

Hi IBLOWN,

Wouldn't the scantool display the commanded AFR as read from the ECM versus your wideband displaying the actual AFR read from the exhaust...?

What wideband do you have.

You can check the reading of the wideband: in CL the wideband should show stoichiometric AFR (or oscillating on either side of it).

[IBLOWN]

Hi IBLOWN,

Wouldn't the scantool display the commanded AFR as read from the ECM versus your wideband displaying the actual AFR read from the exhaust...?

What wideband do you have.

You can check the reading of the wideband: in CL the wideband should show stoichiometric AFR (or oscillating on either side of it).


Im not quite sure what EFILive reads. My oxy sensors are narrow band.

So does that mean the EFILive is only displaying (in ''charts'') as what the ECU is commanding the injectors to run at? I thought it would be displaying what the oxy sensors read?

[joecar]

The AFR pid is the commanded AFR.

The Block Learn and Integrator pids are the long and short term fuel trims, these indicate whether the actual AFR is following the commanded AFR (when in proximity to the stoichiometric AFR).

The NBO2 doesn't report the actual AFR... rather the NBO2 voltage switches/cycles across 450mV as the ECM and NBO2 respond to each other... the ECM knows that the actual AFR is close to stoich when the NBO2 responds by switching (which in turn causes the ECM to switch the other way, and so on... in a closed loop manner).