Doc
November 19th, 2006, 05:36 PM
In my never ending quest to get my car to command and put out exactly what I demand I was wondering if anybody could shed more light on this PID? I have done the AutoVE and rescaled my MAF for CL operation. I am noticing a situation where when I command an AFR value (13 AFR) in PE based on RPM {B3618} and the scanner is reporting a different commanded value (11.7 AFR). I take it I have a modifier table or two interfering/not making sense. After searching thru the modifiers I came upon {B3659}, Commanded fuel in piston protection mode which was commanding 11.7 to 1 AFR. Awfully suspicious, but alas I don't think it is possilbe for this to be enabled based on the qualifiers. It did lead me to Appendix B of the tuning manual. On page 90 it states...
"The converted AFR values may not be absolutely accurate because an off board tool can never know the exact EQRatio to which the offsets will be applied when the engine is operating."
And it goes on to say
"An off board tool can never know that final AFR (or EQRatio) value since it can never know the currently commanded EQRatio or AFR value..."
And it further goes on to say
"This is one reason why the PCM and most competent PCM tuners do not work in AFR, but in EQRatio or Lambda. EFI Live provides the AFR display mode in order to ease first time users into the concept of EQRatio and or Lambda."
This all lead me back to the scan tool. I thought I would like to be one of the competent tuners and walk away from AFR and use EQRatio soley. It works better for me when I VE tune and rescaling the MAF. The end kicker is trying to figure out how to use this PID, Commanded EQRatio. More so everytime I read the statement about "An off board tool.." Well, what about the RR's emulator? Doesn't it (the RR) know what the current EQRatio or AFR the PCM is commanding? Could it not be configured to accept/respond to analog data from a wideband vs. Commanded AFR/EQRatio?
I can "make" this PCM do my bidding, but that just sounds like an easy way out. Like, LS1edit.
Obtw I am currently using/observing all of this with GM's stock 1222156 OS.
And finally, I ran out of time tonight but, I am going to change the Commanded fuel values to display in Default EQ units and recheck all the modifiers to see if they are sane or jacked up. Thanks for the read, I am stepping away from the AFR woobie.
"The converted AFR values may not be absolutely accurate because an off board tool can never know the exact EQRatio to which the offsets will be applied when the engine is operating."
And it goes on to say
"An off board tool can never know that final AFR (or EQRatio) value since it can never know the currently commanded EQRatio or AFR value..."
And it further goes on to say
"This is one reason why the PCM and most competent PCM tuners do not work in AFR, but in EQRatio or Lambda. EFI Live provides the AFR display mode in order to ease first time users into the concept of EQRatio and or Lambda."
This all lead me back to the scan tool. I thought I would like to be one of the competent tuners and walk away from AFR and use EQRatio soley. It works better for me when I VE tune and rescaling the MAF. The end kicker is trying to figure out how to use this PID, Commanded EQRatio. More so everytime I read the statement about "An off board tool.." Well, what about the RR's emulator? Doesn't it (the RR) know what the current EQRatio or AFR the PCM is commanding? Could it not be configured to accept/respond to analog data from a wideband vs. Commanded AFR/EQRatio?
I can "make" this PCM do my bidding, but that just sounds like an easy way out. Like, LS1edit.
Obtw I am currently using/observing all of this with GM's stock 1222156 OS.
And finally, I ran out of time tonight but, I am going to change the Commanded fuel values to display in Default EQ units and recheck all the modifiers to see if they are sane or jacked up. Thanks for the read, I am stepping away from the AFR woobie.