Need help understanding commanded Lambda and setting it up

I have a 2009 Chevy Silverado CC, 5.3, 6 spd, 4x4 and put big tires on it. I tuned the trans using Bluecats tranny software which saved my life and now I am tuning the MAF. I have watched the Greg Banish Calibrated Success DVD a hundred times now and have a fairly clear understanding of what I am doing and what my results should be. I have done Gregs process of setting up the PIDs and histograms and found Bluecats EQ - VE software to use and I have the AFX O2 set to read in Lambda using Gregs formula from another posting.

One thing that is confusing to me is the variable Stoich settings in the PCM and how to tune for it. In Greg's example he says to use CMD HI RES/Stoich and I fould one that said to use 1/commanded EQ ratio. I am not sure which one to use because I do not know if the variable of the 1/EQ ratio is different than the one Greg suggests of CMD HI RES/Stoich.

Moving on to Lambda error I tried two different ways and both come up with a number but one seemed like a funny number. I used the PID of
100*([AUX.20121]-[USER.9004])/[USER.9004] and its reading seemed like the numbers were far to big to be a Lambda error like -15 to +15. The Method that seemed to give a more accurate reading was the PID [AUX.20121]/[USER.9004] which gave a Lambda type number of .80 to 1.10.

I guess my question is what should my Stoich be in the PID CMD HI RES/ Stoich or should I use the EQ ratio PID? Also, if the reading in the PID 100*([AUX.20121]-[USER.9004])/[USER.9004] is accurate how do I correlate that to make changes to my tune?

Thanks in advnace
Adam

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This should answer most of your questions. It started as a Gen.3 E85 thread and ended as a Gen.4 lambda thread.

http://www.hptuners.com/forum/showth...deband-and-E85

jim2092

Thanks for the link. I think I follow what is being said there and how to set it up. I think I had been doing it but need to double check. My question is using the Lambda error PID like you have, how would you use that info to adjust the MAF tune. I understand the way Greg does it and how to apply but am still unclear how to use the EQ ratio derived Lambda error PID. I am going to re-read the link you sent and see if I can digest it a bit more.

Thanks for the help,
Adam

The +15 -15 numbers and the .85 1.15 numbers are the same. One is giving you a multiplier and one is giving you percent error. If you are going to use copy paste special you need the percent error (+/-15) which can be used like a fuel trim.

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Originally Posted by AJohn6

jim2092

Thanks for the link. I think I follow what is being said there and how to set it up. I think I had been doing it but need to double check. My question is using the Lambda error PID like you have, how would you use that info to adjust the MAF tune. I understand the way Greg does it and how to apply but am still unclear how to use the EQ ratio derived Lambda error PID. I am going to re-read the link you sent and see if I can digest it a bit more.

Thanks for the help,
Adam

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If you had asked me that question 2 years ago when this thread was created I probably would have a good answer. But I noticed where I questioned the need for lambda error even then. But to answer your real question as best I can from a failing memory. The real tuning usefulness of this total setup is populating a properly setup histogram for MAF and VE with lambda data that can be used to multiply into the existing MAF/VE tables to make accurate tune changes from logs. A small example: after logging you have several cells in your MAF histogram that show .97 lambda values when they should show 1.0. So here we have these cells showing a little rich. You can go over to the MAF table in your tune and just multiply those cell values by .97 and they are leaned by the appropriate amount without a bunch of mathematics involving the AFR for the fuel being used. This of course is after the tune has been setup for a MAF only tune.

Yep the simple functions of the system is this. PCM commands a target EQ Ratio. You use that EQ Ratio to compare against your wideband which should be setup to report lambda. To compare "like" units you must convert the target EQ Ratio into lambda. This process is slightly different for certain cars because GM changed how EQ Ratio is reported on the E38/67 applications. But Gen3 and E40 uses 1/EQ Ratio = Commanded Lambda. E38/67 uses EQ Ratio = Commanded Lambda.

The ultimate goal is to create a Lambda Error PID to log directly into your VE histogram or MAF histogram so that the % error is plotted in the region the car was running. This can then simply be copied and paste special multiply by % into your MAF or VE table. It is important that you are running in either SD or MAF only when calibrating one of the two airflow tables so that you know the source of airflow is from the table you are adjusting.

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Originally Posted by LSxpwrdZ

Yep the simple functions of the system is this. PCM commands a target EQ Ratio. You use that EQ Ratio to compare against your wideband which should be setup to report lambda. To compare "like" units you must convert the target EQ Ratio into lambda. This process is slightly different for certain cars because GM changed how EQ Ratio is reported on the E38/67 applications. But Gen3 and E40 uses 1/EQ Ratio = Commanded Lambda. E38/67 uses EQ Ratio = Commanded Lambda.

The ultimate goal is to create a Lambda Error PID to log directly into your VE histogram or MAF histogram so that the % error is plotted in the region the car was running. This can then simply be copied and paste special multiply by % into your MAF or VE table. It is important that you are running in either SD or MAF only when calibrating one of the two airflow tables so that you know the source of airflow is from the table you are adjusting.

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I understand tuning in MAF only or SD but it was on my 2000 GEN III which seemed a lot less difficult to figure out. I had to find the Bluecat software to adjust the coefficients to a VE table and then make a table because my histogram doesn't have a supportable table for Primary VE vs. RPM vs. MAP. So... Haha, I know I'm a pain, but how do I know which equation to use? Whether it is the 1/EQ Ratio=Commanded Lambda or EQ Ratio = Commanded Lambda?

Thanks for the replies guy's its helping me understand it.

If you need bluecat it's EQ=lambda

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Originally Posted by Kyne

If you need bluecat it's EQ=lambda

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Ok, exactly the answer I was looking for. I thought when I logged it as 1/EQ ratio it did not look right. Thanks again Kyne and those Holdens are cool cars. I wanted to drive one when I was in Sydney but never got the chance to.