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) |
This is the main user-adjustable MAF compensation table. The In (hz) column is the frequency coming directly into the ECU. You can datalog this frequency as MAFRaw (simply add MAFRaw to your Captured Values and/or the Display Values list to see it). Note that when running a GM MAF straight to the ECU, you're going to use GM MAF-like frequencies, NOT Mitsubish MAF-like frequencies. You will be idling in the 500hz range, for example, rather than the typical Mitsubishi MAF area of 50hz.
NOTE: Setting this table up, particularly for a GM MAF running straight to the ECU, can be a little tedious. We are defining adjustment wizards (datalog extensions) to help with this. You can get information on our wiki at the following URL:
Base MAF type is provided in 1GV2 and V3. Use this drop down to select the basic type of MAF sensor you have connected directly to the ECU. Only select one of the GM MAF options if you're actually running the GM MAF straight to the ECU using our GM MAF cable. Do NOT select any of the GM MAF options if you're running a MAF translator. The MAF translator is supposed to output a frequency that looks to the ECU like a factory Mitsubishi MAF. So you will want to select "Stock" as your base MAF type when running a GM MAF translator.
In the V3 version of this tab, you'll see a Global scalar field. This field applies an adjustment across the board to the incoming MAF signal. This is mainly useful while running with a GM MAF. Because this sensor is very sensitive to variations in installation, it's not at all uncommon to need 30-40% adjustment to this signal across the board. You can apply this adjustment using the Global scalar field.
This button brings up a helper/wizard type dialog to help with making changes to the Global scalar field. At issue here is the fact that this is a "scalar" field. Meaning it's applied as a factor or multiplier to the adjustments in the MAF compensation chart. So you can't simply set the Global scalar field to some offset and then slide all the MAF compensation sliders up or down by that same amount. You have to actually rescale the table.
In the Change... dialog, you'll see a field where you can specify a new global scalar. The application will take the ratio of current to new and readjust the MAF compensation values appropriately so that when it's done, the total compensation you had before (global times MAF compensation) will be identical to the compensation you have after with the new global value specified. You can also use the Auto Adj button to let the application automatically center the total compensation around 0%.
This drop down provides some basic "templates" you can use for reference when running modified versions of the base MAF. For example, if you have a 2G ECU and you have Stock selected in the Base MAF type drop down, then the templates drop down will provide an option to display a template for running a Hacked 2G MAF. A selected template is just an overlay on the Active MAF Compensation table. It doesn't actually change any values used by the ECU. It's a display-only template for reference. To use template values as your actual values, click the Use template button while a template is displayed.
This checkbox controls whether or not the MAF compensation sliders are used or ignored during SD operation. Normally, for SD operation all airflow adjustments should be made by altering the SD VE table values rather than by applying MAF compensation settings. Having this checkbox checked permits easy switching between MAF and SD operation during the initial SD VE table adjustment process.
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