Someone on here complained that I don’t contribute to this forum any. So, I figured I would give a contribution for you tuners, calibrators, and Pro Racers.
Today I want to talk about a table I get asked about frequently. "LoadwithfailedMAF" or LWFM (applies to prior 11MY in the mustang line). Take CDC3 for consideration.
MAF transfer function - MAFTF
Forced induction – FI
Load with failed MAF - LWFM
Before 2002MY on some vehicle lines, this table would only be used when the MAF did fail, and its only function was to substitute a value in for load.
When development started on the some early platforms, it was decided to add more responsibility to this table. One of those ideas was to use LWFM to anticipate the amount of AIR that is going to be entering the engine for the next 2 cylinder events for each cylinder, or a total of 4 engine revolutions. Initial fuel calculation is based of this table, then the MAF transfer function.
At WOT the load calculated by the MAF transfer function can NOT be more than the load calculated by LWFM * WOT Multiplier and it cannot be less than the Correction for MAX Aircharge. This can bite you in the tail when you start dealing with FI cars. If you do not raise these values, the Fuel calculation function picks the lower value from MAFTF vs LWFM, modified for correction, times these values. Which can be deciving by making the MAFTF appear to have no effect.
In my research, some tuners start setting these values to 1.99, which fixes the WOT problem (looks good on a dyno), however it hurts part throttle air anticipation. There are two ways to address this, there is the "proper" OEM way, and the "screw it lets get this bitch of the dyno" way.
Option 1: With the vehicle on a load bearing dyno. Run the vehicle at a constant throttle position, then record the load as RPM increases, then re-create the LWFM table with these values. For you PRP's this is way to much work, see option 2
Option 2: If you are 100% behind your MAFTF, then you can disable Anticipation Logic by setting "Anticipation Logic" to Zero. This disables anticipation logic and then only uses MAFTF for aircharge calculations.
BONUS: If you have a car that has ridiculous cams, and your 100% behind your MAFTF, set this to zero to help with tip ins.
One more thing I want to add on the FI subject. Its pretty common for people to move the ACT sensor after the blower, which in turn raises ACT's. There is a table called Voleff Correction for ECT&ACT. It modifies the load calculated by LWFM. It multiplies the LWFM by the corresponding value based on ECT&ACT. This should be addressed, as when ACT's get over 100F, these values should be lowered to better reflect the actual values.
Cheers,
-Matt
Today I want to talk about a table I get asked about frequently. "LoadwithfailedMAF" or LWFM (applies to prior 11MY in the mustang line). Take CDC3 for consideration.
MAF transfer function - MAFTF
Forced induction – FI
Load with failed MAF - LWFM
Before 2002MY on some vehicle lines, this table would only be used when the MAF did fail, and its only function was to substitute a value in for load.
When development started on the some early platforms, it was decided to add more responsibility to this table. One of those ideas was to use LWFM to anticipate the amount of AIR that is going to be entering the engine for the next 2 cylinder events for each cylinder, or a total of 4 engine revolutions. Initial fuel calculation is based of this table, then the MAF transfer function.
At WOT the load calculated by the MAF transfer function can NOT be more than the load calculated by LWFM * WOT Multiplier and it cannot be less than the Correction for MAX Aircharge. This can bite you in the tail when you start dealing with FI cars. If you do not raise these values, the Fuel calculation function picks the lower value from MAFTF vs LWFM, modified for correction, times these values. Which can be deciving by making the MAFTF appear to have no effect.
In my research, some tuners start setting these values to 1.99, which fixes the WOT problem (looks good on a dyno), however it hurts part throttle air anticipation. There are two ways to address this, there is the "proper" OEM way, and the "screw it lets get this bitch of the dyno" way.
Option 1: With the vehicle on a load bearing dyno. Run the vehicle at a constant throttle position, then record the load as RPM increases, then re-create the LWFM table with these values. For you PRP's this is way to much work, see option 2
Option 2: If you are 100% behind your MAFTF, then you can disable Anticipation Logic by setting "Anticipation Logic" to Zero. This disables anticipation logic and then only uses MAFTF for aircharge calculations.
BONUS: If you have a car that has ridiculous cams, and your 100% behind your MAFTF, set this to zero to help with tip ins.
One more thing I want to add on the FI subject. Its pretty common for people to move the ACT sensor after the blower, which in turn raises ACT's. There is a table called Voleff Correction for ECT&ACT. It modifies the load calculated by LWFM. It multiplies the LWFM by the corresponding value based on ECT&ACT. This should be addressed, as when ACT's get over 100F, these values should be lowered to better reflect the actual values.
Cheers,
-Matt
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