Setting up AFR Error PID for LC-1 through EGR.

[Mike H.]

Got my LC-1 working through EGR on '00 Ls1 F-body. I can get it to datalog fine and I have it displaying histogram of my user created PID "My AFR" over the VE table. My problem comes where you try to make an AFR Error PID. I tried setting it up like the how-to on this forum but it shows as unsupported parameter. I even tried just logging the [SENS.121] (commanded AFR) and it won't log. Do I need to be logging the commanded AFR in the table to make this PID or what? Sorry if this is unclear. Thanks.

[blownbluez06]

if you named your EGR wideband pid "afr" in the drop down, it should understand that you're using your EGR pid as your AFR reference and the AFR Error pid should work. I just did this yesterday through the A/C switch.
You also might try the custom PID
100*(([PID.2811]/.334)+7.39-[SENS.121])/[SENS.121]

copy and paste it.
Use logworks to make sure you have the full range of the LC1 going 7.39-22.35 for this PID formula to work.

[5_Liter_Eater]

There is a bug to where the built in AFR Error PID will display for a log when you take it but if you close the log and re-open it, the built in AFR Error PID goes to "unsupported parameter".

So as long as your AFR PID is defined as and AFR meter and you are logging commanded AFR (low or high res) then you can create a user defined PID for AFR Error using your user defined PID for AFR:

100*([USER.9009]-[SENS.121])/[SENS.121]

Replace user.900x with whatever number user defined PID your AFR PID is. IE: Mine is user defined PID 9 so I read USER.9009. This way if you end up changing your AFR function you don't have to remember to go back into your AFR Error PID to change it there too.

But it sounds as if you're not logging commanded AFR currently. None of this will work without logging commanded AFR. It needs to know that to compare it against the actual AFR to calculate the error. Commanded AFR ends up to be SENS.121 whether you log the low res or high res PID. I recommend the low res PID if you have a choice. Uses less bytes.

[Mike H.]

Ok I think thats my problem 5LE.. I wasn't logging commanded to begin with. I'll give it a shot. I forgot to mention I am using 2.22 so I can't use my user PID as an AFR to log I have to set up another custom PID.

BlownBlueZ I have the AFR reading properly with my own PID, I was just having issues on the AFR error % PID. And I think my problem is I wasn't logging Commanded AFR.

[Mike H.]

I'll let you guys know if that works, thanks again.

[5_Liter_Eater]

OK, if you're using 2.22 then you definitely can't use one user defined PID inside another so you have to set it up like Bret said.

[Mike H.]

It works, my problem was I wasn't logging Commanded A/F. Thanks guys,

[JeremyBlackwell]

Hi guys,

Sorry to dig up a slightly old thread. But, given that I am encountering the same issue with no resolve despite lots of searching and trail/error, I wanted to open this back up to see if there are any other suggestions besides the ones above which might lead to a solution.

The car is a 1997 C5 with 2bar OS (version 2.22). I am logging from an Innovate LM1 that I have output to the EGR pin on the PCM (which was originally an empty PCM input, but I pinned it.)

I have attached my .cfg and log files. You will notice four 'test' WB AFR % Error files which I have tried. They are only loosely set up, so please disregard the scale on the graph/etc. I do not know exactly which one is correct, but it seems the simple algorithm of this would be correct:
(actual AFR - commanded AFR) / commanded AFR x 100

They all display data, but are incorrect. The 'Command AFR' datastream doesn't look correct, which is a core variable. The Open Loop EQ Ratio chart on the Editor is 1.00 across the board. I've chased my tail for 5+ hours to the point of confusion and second guessing things. Any ideas?

[5_Liter_Eater]

Use defined PIDs are kept in the "vcm scanner.cfg" file. We'd need that in conjunction with the posted config file to look at your custom PIDs.

[JeremyBlackwell]

Okay, here you go! Thanks.

[5_Liter_Eater]

I don't see a user defined PID for AFR, just AFR Error and the AFR error is wrong.

(([SENS.121]/.5+9.8)-[SENS.121])/[SENS.121]*100

SENS.121 is commanded AFR. You're trying to use the transfer function against commanded AFR. Here is the built in AFR Error PID:

100*([SENS.120]-[SENS.121])/[SENS.121]

It compares SENS.121 (commanded AFR) against SENS.120 which is actual air fuel ratio. So you need to set up a a user defined PID for AFR and define it as an air fuel ratio sensor. Then it will be referencable as SENS.120 and the built in AFR error PID will work. The only problem is that the built in AFR error PID stops working when you save the log, close it and re-open it. It doesn't recognize the user defined PID for AFR as an AFR sensor anymore. So thats why it's good to have your own AFR Error PID that doesn't use SENS.120. My AFR Error PID is: 100*([USER.9009]-[SENS.121])/[SENS.121] where USER.9009 is my AFR user defined PID.

[JeremyBlackwell]

I don't see a user defined PID for AFR, just AFR Error and the AFR error is wrong.

(([SENS.121]/.5+9.8)-[SENS.121])/[SENS.121]*100

SENS.121 is commanded AFR. You're trying to use the transfer function against commanded AFR. Here is the built in AFR Error PID:

100*([SENS.120]-[SENS.121])/[SENS.121]

It compares SENS.121 (commanded AFR) against SENS.120 which is actual air fuel ratio. So you need to set up a a user defined PID for AFR and define it as an air fuel ratio sensor. Then it will be referencable as SENS.120 and the built in AFR error PID will work. The only problem is that the built in AFR error PID stops working when you save the log, close it and re-open it. It doesn't recognize the user defined PID for AFR as an AFR sensor anymore. So thats why it's good to have your own AFR Error PID that doesn't use SENS.120. My AFR Error PID is: 100*([USER.9009]-[SENS.121])/[SENS.121] where USER.9009 is my AFR user defined PID.

Hi, I do have AFR set up as a PID, which is USER.9004. Also, one of my four attempted PID for AFR Error % appears to be set up correctly as per your instruction, which is USER.9008.

Are these still incorrect? I do not see how. Thanks for your advice!

[5_Liter_Eater]

Hmmm, I do see it in the vcm scanner.cfg file now that you mention it, but it wasn't available to display when I opened the log. Why are there so many AFR Error PIDs? The only one thats right is the 4WB AFR % Error (user.9008). If if I add that one to the chart or dashboard it displays properly.

<add key="4" value="WB AFR,WB AFR,120,130,([PID.2811]/.5)+10" />
<add key="5" value="WB AFR % Error,WB AFR,120,100,(([SENS.121]/.5+9.8)-[SENS.121])/[SENS.121]*100" />
<add key="6" value="2WB AFR % Error,2WB AFR % Error,121,100,([SENS.120]-[SENS.121])/[SENS.121]*100" />
<add key="7" value="3WB AFR % Error,3WB AFR % Error,120,100,100*(([PID.2811]/.334)+7.39-[SENS.121])/[SENS.121]" />
<add key="8" value="4WB AFR %Error,4WB ERR,120,100,([USER.9004]-[SENS.121])/[SENS.121]*100" />

[JeremyBlackwell]

Hmmm, I do see it in the vcm scanner.cfg file now that you mention it, but it wasn't available to display when I opened the log. Why are there so many AFR Error PIDs? The only one thats right is the 4WB AFR % Error (user.9008). If if I add that one to the chart or dashboard it displays properly.

<add key="4" value="WB AFR,WB AFR,120,130,([PID.2811]/.5)+10" />
<add key="5" value="WB AFR % Error,WB AFR,120,100,(([SENS.121]/.5+9.8)-[SENS.121])/[SENS.121]*100" />
<add key="6" value="2WB AFR % Error,2WB AFR % Error,121,100,([SENS.120]-[SENS.121])/[SENS.121]*100" />
<add key="7" value="3WB AFR % Error,3WB AFR % Error,120,100,100*(([PID.2811]/.334)+7.39-[SENS.121])/[SENS.121]" />
<add key="8" value="4WB AFR %Error,4WB ERR,120,100,([USER.9004]-[SENS.121])/[SENS.121]*100" />

Bill,

I just came back here to post that the issue is solved. However, I'm not quite sure how...

After I posted my last reply, I went to the Scanner and deleted the other three user configurable PIDs for the (incorrect) AFR Error %. Then, the log displayed the AFR error % correctly. Not quite sure what I did to fix it, which is frustrating. I do not just want the error 'fixed', I want to know WHY it is 'fixed' so that I, and everyone who might see this thread in a future search, also know WHY. I'm going to restore the old PID and see if I can isolate it. Then, I'm going to go play with the car! Thanks for your advice sir.

[JeremyBlackwell]

One more thing I just thought of before I dig into things...if there are user configurable PID which reference the SAME SENSOR ('Air Fuel Ratio' in this case), will that cause a conflict with other user configurable PID which also are set to reference the same sensor (AFR)?

[5_Liter_Eater]

Multiple PIDs defined as the same sensor can confuse the scanner yes. I've seen that when peole try to create boost PIDs and define them as MAP sensors. Changing up the user defined PIDs can also screw with a log taken when the config was different. I would:

- Delete the extraneous AFR Error PIDs.
- Add the user defined AFR and AFR error PIDs to the table.
- Take a new log using this config and verify that the PIDs are reading right in the table.

[JeremyBlackwell]

Multiple PIDs defined as the same sensor can confuse the scanner yes. I've seen that when peole try to create boost PIDs and define them as MAP sensors. Changing up the user defined PIDs can also screw with a log taken when the config was different. I would:

- Delete the extraneous AFR Error PIDs.
- Add the user defined AFR and AFR error PIDs to the table.
- Take a new log using this config and verify that the PIDs are reading right in the table.

Having multiple 'test' PIDs using the same sensor must have indeed been the issue. AFR Error % is working perfectly now! Thanks!

[5_Liter_Eater]

Beauty!