Manual AFR control with Scan Tool

[2002_z28_six_speed]

When you guys use the Manual Aux Control (F5) to adjust your AFR doesn't it work accurately?

Just as an example:

I will 14.7 Commanded and see 14.7 on the WB. Because it was tuned that way.

I adjust the manual AFR to command 13.8 with one click. 14.0 will show up on the wideband. I click one more time for 12.8. The WB will show something like 13.2 or 13.3.

In other words the PCM always underadjusts or the adjustment are always flawed. Is this how it is in reality?

Thank you.

[joecar]

It's been a while... I'll check that out tonite after dinner...

[joecar]

Going to bidir control of AFR, my wideband shows the same AFR as what is being commanded

(this indicates my VE table has been "corrected").

[2002_z28_six_speed]

So when you adjust you AFR live through the BIDI controls it is pretty accurate? Thank you.

[joecar]

Yes.

[Biggsy]

So when you adjust you AFR live through the BIDI controls it is pretty accurate? Thank you.

Only if your VE table is correct. If it is not, you will see a difference between commanded and actual. The PCM through its normal operation will not know that its out (when in Open Loop).

[2002_z28_six_speed]

Just to be clear I am saying if I order 14.7 and tune 14.7 it ends up being 14.7.
But if I change it with the live tool from the AFR I tuned it for it doesn't seem to be exact 100% on.

[Biggsy]

Just to be clear I am saying if I order 14.7 and tune 14.7 it ends up being 14.7.
But if I change it with the live tool from the AFR I tuned it for it doesn't seem to be exact 100% on.

Had to read what you said a couple of times but I am now on the right page now.

When then program commands say 12.5 does the WB show 12.5? (not talking about scan tool command)
The only reason I ask is that 14.7 is around stoich and could be in closed loop, NB O2 sensors could be compensating even though the VE is wrong.