Formula help for Calculated Pid

[vetteboy2k]

I am looking to create a calculated pid for .5V = .68 Lambda and 4.5V = 1.36 Lambda

I understand how to type all the information into the calc_pids file I just am unclear on the math behind coming up with the equation

The equation for the AFR .5V = 10 and 4.5V = 20 is
{EXT.AD1} * 2.5 + 8.75

Can anyone help me understand how to come up with the same for the Lambda values

[vetteboy2k]

Also is there any way to create a calculated pid for Serial Lambda and Analog Lambda? I tried using B3605 however an error occurred when opening the scan tool

[mr.prick]

Depending on who you ask, Lambda = 14.7AFR
(AFR/14.7) = Lambda
or
{EXT.AD1}*2.5+8.75/14.7
If you have serial just select EXT.WO2LAM1, why convert it to analog?

[vetteboy2k]

Thank you, haha I was way over complicating things!

I now have
factor 0.0 2.0 .2 "{CALC.LAM_FJO} / ({GM.AFR} / 14.7)"

As for the BEN for Serial Lambda, I didn't see a pid for BEN lambda serial so just getting ready for it. There is a BEN for Serial AFR just not Serial Lambda

This is what I will have
factor 0.0 2.0 .2 "{EXT.WO2LAM1} / ({GM.AFR} / 14.7)"

Thank you for your clear headed thinking on this one!

[joecar]

For serial AFR, the pid is BEN1.

[vetteboy2k]

Yes, but what is the BEN for serial LAMBDA?

[vetteboy2k]

I ordered a universal serial cable from TAq cables to hook up to my FJO, in the mean time I am trying to get the analog external 1 working properly. The FJO read 14.55 while V2 when scanning reads 14.11 making dialing things in difficult. What is the next step in dialing in the Analog?

[mr.prick]

For BEN from Lambda you will need another PID
to convert commanded AFR to commanded Lambda:
{GM.AFR}/14.7

Why are you basing everything off of Lambda?
You may end up upside down with all the PID conversions and
the PCM uses EQ {B3601} anyways which is the opposite of Lambda.
Use AFR or EQ for tuning.

[vetteboy2k]

B/c of different fuels and levels of Ethanol and when using methanol as well. Lambda never changes... stoich is stoich

[mr.prick]

Stoich is different between fuels. Stoichiometry
Gasoline 14.7 : 1 — 6.8%
Natural gas 17.2 : 1 9.7 : 1 7.9%
Propane (LP) 15.5 : 1 23.9 : 1 6.45%
Ethanol 9 : 1 — 11.1%
Methanol 6.4 : 1 — 15.6%
Hydrogen 34 : 1 2.39 : 1 2.9%
Diesel 14.6 : 1 — 6.8%

Lambda is going to change and the PID is based off 14.7AFR
You can change this for each fuel type.