Need some help.

[mr.prick]

Yea but what I am trying to say I guess is my AFX does not give me lambda, it gives me A/F ratio. So where does it ever tell me what stoich is? If it was reporting lambda then I would completely understand. I am getting my lambda based off my actual A/F vs Commanded A/F.

The AFX gives you Lambda but does the PCM?
You will need Lambda from the PCM to compare to actual Lambda.
This is the PID for Lambda for the AFX.

#Units         Low      High     Fmt    Expression
#------------ ---------- ----------- -------- --------------------------------------------------------------
*CLC-00-027
lambda       0.00       1.60         .3        "({EXT.AD1}*0.096)+0.62"

#Code                                  PRN         SLOT            Units          System                Description
#--------------------------------- ----------- ------------------- --------------- -------------------- -----------------------------------
CALC.LAM_NGK1             F027     CLC-00-027      lambda       WO2-Analog       "Wide Band Lambda 1 - NGK AFX" 

It's just a matter of converting voltage to a number you want.
If the PCM gives you commanded Lambda you can use that.
If it doesn't you can always make another PID for commanded Lambda (Stoich AFR/Commanded AFR) and
then another for the multiplier (CALC.LAM_NGK1/Commanded Lambda).
If you use AFR then you need to take the Lambda range of the WBO2 & the PCM stoich AFR value to make a new PID.

The Lambda expression is absolute.
i.e. this is the true conversion for data from the AFX.
The AFR expression: ({EXT.AD1}*1.4)+9 is to convert the Lambda output to an AFR value of choice.
Think of it like this
(1+1)=2 true or (1*x)+b=2 choice

[J.Abbott]

Ok, I follow what you are saying. But if I do the formula for Lambda based off what you just had for the AFX and using 3.958 for the voltage that you referenced earlier, then I get .99 lambda. My question is where does 3.958 come in at. The W/B outputs voltage not lambda or a/f, it is our equations that change them into either correct. So if I change my PCM to give me commanded lambda, then how does my meter know what lambda is 1.00. Isn't the way I just wrote the pid for WB AFR/Commanded AFR work.
I mean if my PCM knows that 14.44 is 1.00 lambda, then how do I get my lamda error from that. Maybe I am reading too far into this and confusing myself, but I am not following your logic on this. If I am converting my WB voltage into Lambda, would the formula have to change depending on what my Stoich is?

[joecar]

your fuel (gasoline): stoich = 14.63
your calibration: stoich = 14.63
your wideband: stoich = 14.57 (what does your wideband's user manual say...?)

your wideband outputs a voltage that is proportional to both Lambda and AFR (since Lambda = AFR / stoich)...

mr.prick took the wideband AFR formula and divided it by 14.57 to arrive at the wideband Lambda formula.

i.e.:
- your calibration will cause the PCM to calculate fuelmass based on 14.63;
- your NBO2 will switch around your fuel's stoich of 14.63 which is lambda = 1.00;
- your wideband will indicate 14.57 when Lambda = 1.00;
- if you use wideband AFR to correct VE/MAF tables, then your correction will contain error;
- you have to correct your wideband AFR to actual AFR by multiplying by (14.63/14.57).

Yes, your formula has to change, divide it by 14.57 to get Lambda.

[joecar]

Sanity check: are we all certain that the NGK wideband assumes a stoich AFR of 14.57 (i.e. we have to have the correct value)...?

Can someone post a link or pdf that shows this.

[Taz]

Yes .... NGK AFX uses 14.57:1 AFR as stoichiometric ...on page 11 & 12 in the attached manual ...


Regards,
Taz

Attachment 8971

[joecar]

Ok, that's a very good document...

That document has all the info for writing a Lambda calc pid (which avoids reliance on stoich AFR)...

Then if EQIVRATIO is logged, the BEN would be EQIVRATIO multiplied by wideband Lambda.

[J.Abbott]

Ok, I think we are all on different pages here. I see in the manual and I understand what you are saying, but that works if I am pulling Lambda. If the meter (gauge) is saying 1.00 it has to know what the voltage is for 1.00 lambda in order to have the correct display. If the meter has been set at 14.57 stoich that is fine. I can set my commanded to what ever I want, the meter is still going to read the correct A/F ratio. If I want my Stoich to be 12:1 and the meter is reading 14.57 that is actaully what the engine is doing and with the lambda pid I wrote it will give me a lambda of .82. When I tune the VE to get 12:1 A/F which is what the engine is doing then my lambda will read 1.00.
The reason I did it this way so no matter what my commanded A/F I will always have a correct Lambda reading between my meter and my lambda.
If I do this the other way by importing lambda, what happens when I am commanding .85 but my meter is looking for 1.00, and I really want .85?

[J.Abbott]

I am not trying to be hard headed and I appreciate all the input. I am just trying to understand what you are explaining. I think the issue is how we look at it, I don't look at any of in Lambda, I look at it as A/F and lambda just a equation to multiply my VE table by. I know that most of the world outside of the US looks at it as Lambda, and I am trying to bring myself to use all metric including Lambda. However old habits are hard to break and I can quickly determine where I am using A/F where as using Lambda I have to think about it for second.
I would like to know more about the voltage offest that Mr. Prick was talking about earlier, I have noticed my WB guage is reporting 14.74 and fluctuating a little where as I am reporting 14.44-14.60 in the scanner. The scanner seems a little more stable then how quickly the gauge is fluctuating also.
Thanks
Justin

[WeathermanShawn]

It is not an easy subject to understand.

Whenever I get stuck on understanding a concept, I try to take a new approach.

Irregardless of your method ..in your tune..what is the published Ratio of Air to Fuel for Stoichiometry..(in the LS1..it is B3601).

That will tell us how much farther this debate should go. At this point it is less about the wideband as it is having your tune and wideband match.

[J.Abbott]

{B3671}LS2 I have it set to 14.22, I understand what they are saying, but by having the pid written the way I do, the Lambda error is always correct no matter what my commanded A/F ratio is. If I change everything to Lambda and I think that is what they are saying that the voltage has to be fixed, which I agree. But by running it as A/F it fixes itself and removes a step I have to do. That is if I am looking at this correctly.