MAF Comp Settings


MAF compensation refers to the adjustments made to the airflow signal coming into the ECU before the reset of the ECU code is allowed to "see" it.  The ECU makes a number of decisions based on airflow data and it calculates its basic fuel delivery from airflow.  So getting an accurate airflow reading into the ECU is extremely important.  The MAF Comp tab provides a way to make these adjustments.

It's important to understand the extensions to airflow calculation that are in place with ECMLink.  First, the frequency coming directly into the ECU is stored in a variable called MAFRaw.  You can datalog this value by simply adding MAFRaw to your Captured Values and/or the Display Values list.

ECMLink applies a base MAF compensation to this value (as specified in the Base MAF type drop down) and then applies the user adjustment specified in the Active MAF Compensation table.  The result is stored in a variable called MAFComp.

ECMLink then clips the MAFComp value according to the Idle Air Settings.  This clamped value is stored in MAFIdle.

After this, MAF Clamp values are applied (if active) and the result is stored in MAFSD.

And, finally, a decision is made whether to use MAFSD or MAFIdle as the final MAF value.  This decision is based on whether the MAF clamp function is enabled and active or not.  The result is stored in a final MAF value that the rest of the ECU code is allowed to see and use.

The complete chain of events is illustrated below.

Signal from MAF
-> MAF Raw (LOG: MAFRaw)
   -> Base MAF type compensation (1GV2 or V3 only)
      -> Active (User) MAF compensation (LOG: MAFComp)
         -> Idle airflow (LOG: MAFIdle, V3 only)
            -> MAF Clamp (LOG: MAFSD)
               -> FACTORY CODE (LOG: MAF)