Quick question

[2007chevy5.3l]

Hey guys,

Im gonna try my hand at doing some tuning on my Tahoe with fuel trims and have a question. I set up everything accordingly to what swingtan said in this post http://forum.efilive.com/showthread....l=1#post140595 But i do not know how to create a custom PID to convert the +/- percentage into a BEN since the STFT's are in a "%" reading. Can someone help me out on this?

Thanks,
Justin

[Taz]

Hello Justin,

Attached is an example of fuel trim calc_pids - BEN from LTFT and STFT.


Regards,
Taz

[2007chevy5.3l]

Thank you Taz
So now I just plug that in to the calc pid note pad and save it? Not really sure how it all works....

[Taz]

Hello Justin,

It might be easier if you posted your current calc_pids.txt file. But make a back up copy first.

Go to C:\EFILive\V7.5\User Configuration … you should see your calc_pids.txt file in this directory.

Open this file with Notepad. Then use the “Save as” command – to save an unaltered copy … call it something like calc_pids-original.txt.

Then post a copy of this file … I’ll add in the fuel trim CALC PIDs for you.


Regards,
Taz

[2007chevy5.3l]

Hey Taz,

Heres the Calc Pids. Let me know how you do it so I will know if I ever have to do it again

Thanks a ton!
Justin


calc_pids.txt

[Taz]

Hello Justin,

My apologies for the delay in response ... the appearance of cooler weather here has everyone scurrying to get their projects completed before the snow arrives ... in 6 weeks or so.

In your signature you list "LC-1 Wideband" ... so I assumed this was a Serial WBO for the purpose of the calc_pids ... have never used an LC-1.

In the calc_pids this WBO is represented by the "EXT.WO2LAM1" expression ... you may need to alter this, if I have selected this incorrectly for your setup or this WBO.

Save this file as "calc_pids.txt" in the User Configuration folder ... and it will replace your currently empty file.


Regards,
Taz

[2007chevy5.3l]

Taz,

Yes my LC1 is a serial wideband. I see that you set the calc_pids to EXT.WO2LAM1, I believe this will read in Lambda. I am not very familliar with Lambda since we all use AFR... Will I need to change it to say WO2AFR1??

Thanks!!
Justin

[swingtan]

In all honesty, I wouldn't use a BEN if correcting using the STFT's. I've tried it and gone away from it.

We know that the two banks do not run the same fuel trims and the ECM manages the trims separately. So averaging them together does what the ECM is trying not to do... I chose one bank to work from and generally don't worry about the other unless I'm sanity checking. Remember that tuning is not a substitute for components in good mechanical condition, I'm going to assume that the rest of the engine is working correctly and that the NB O2's are good.

I'd then just log data while driving, ensuring I had the STFT's and other related PID's selected. Once a logging session was complete, I'd review the data and choose specific sections (by looking at where the STFT's were significantly out) and making adjustments to the MAF or VVE based on the sections I chose from the log data. working like this allows you to easily ignore transient area's or areas where you know data may be bad ( hot starts etc ).

Simon

[joecar]

Taz,

Yes my LC1 is a serial wideband. I see that you set the calc_pids to EXT.WO2LAM1, I believe this will read in Lambda. I am not very familliar with Lambda since we all use AFR... Will I need to change it to say WO2AFR1??

Thanks!!
Justin

Use lambda, otherwise AFR will be incorrect unless you used fuel with a stoichiometric ratio of 14.7.

Lambda is independent of the fuel's stoichiometric ratio.

e.g. in each of these cases, when the wideband read stoich it will report lambda as 1.00:
- E00 = stoich 14.7
- E10 = stoich 14.2
- E85 = stoich 9.7


lambda = AFR / stoichAFR

or

AFR = lambda * stoichAFR

[2007chevy5.3l]

In all honesty, I wouldn't use a BEN if correcting using the STFT's. I've tried it and gone away from it.

We know that the two banks do not run the same fuel trims and the ECM manages the trims separately. So averaging them together does what the ECM is trying not to do... I chose one bank to work from and generally don't worry about the other unless I'm sanity checking. Remember that tuning is not a substitute for components in good mechanical condition, I'm going to assume that the rest of the engine is working correctly and that the NB O2's are good.

I'd then just log data while driving, ensuring I had the STFT's and other related PID's selected. Once a logging session was complete, I'd review the data and choose specific sections (by looking at where the STFT's were significantly out) and making adjustments to the MAF or VVE based on the sections I chose from the log data. working like this allows you to easily ignore transient area's or areas where you know data may be bad ( hot starts etc ).

Simon

So what your saying is just log the data and where ever the trims are out then adjust the MAF frequency conversion to get it right??