Wed. Jun 19th, 2019


Electronic Solutions for Motorsport

MAF Scaling – What is it? When to do it & how?

3 min read

MAF scaling is when you adjust the signal from the MAF sensor by a set amount, a scale, and send that adjusted signal to your engine’s ECU

For example, you want to reduce the MAF sensor signal by 10%. To do this, you would MAF scale by multiplying the MAF sensor signal by 0.9

This is the essence of MAF scaling & this is the purpose of the MoviChip MAF Manager

To add a layer of complexity, you could use a different MAF scale, a different multiplier, according to the load on the engine.

MoviChip ATF, automatic, dynamic MAF scaling setup menu in ATF app
MoviChip ATF, automatic, dynamic MAF scaling setup menu in ATF app

Further to this you can scale the MAF according to load and RPM. But this is stretching the definition of “scaling”. Changing MAF signal according to load and RPM is more like retuning the engine than simply rescaling the MAF sensor signal.

Why would you need to rescale your MAF sensor?

Two examples

Larger injectors. As an example. You fit 10% larger injectors, scale the MAF signal by 0.9 to reduce fuel signal by 10%.

Larger MAF sensor. As an example. You move from a 65mm MAF sensor to a 80mm sensor. A 50% increase in tube area, scale MAF signal by 1.5 to maintain same voltage going to ECU

How to scale your MAF sensor?

You need two things

1.A device to alter the MAF signal

2.A wideband lambda sensor so you can monitor your air fuel ratios

MAF Scaling Devices


This is the product we used to use for many years. The product gives a lot of flexibility but in our opinion we found the product to be unnecessarily complicated considering what it was doing ie MAF Scaling

With this product you scale the MAF signal according to TPS (Throttle Position Sensor) and RPM

We have an issue with using TPS. First is that tip in enrichment uses the TPS signal and also, 50% TPS signal at 2000 RPM and 50% TPS signal at 5000 RPM means completely different things, specifically the load on the engine is completely different in these two scenarios.

Tuning by RPM we also found to be unnecessary, ie our MAF scaling figures across the RPM range were similar. The advantage the APEXi AFC NEO has, by adjusting by RPM, is that you can tune for big changes in VE (Volumetric Efficiency) but in our opinion, when you are making big changes to the VE you also need to be addressing the ignition timing, which the APEXi AFC NEO does not address. In short, MAF Scaling on its own is not suitable/enough when you are making big changes to the engine.

MAF scaling is a powerful tool but it has its limits.

MoviChip ATF

We built and designed this product using the lessons we learned from using the APEXi AFC NEO.

As I wrote above, MAF scaling on its own has its limits and we do not try to make MAF scaling into something it isn’t.

Our product solely deals with MAF scaling based on load.

Improvements over APEXi AFC NEO/SAFC

We scale the MAF signal according to load ie a MAP sensor signal, which we believe is superior to TPS because load is load, regardless of RPM, unlike the TPS signal

We do not scale the MAF according to RPM because we believe, if you need to do this, your engine needs a more fundamental re-tune rather than simply scaling the MAF signal.

For example if you change the camshafts, to get the most power from them you need to be looking at a product that can also adjust ignition timing not just fuelling. You can use MAF scaling only but you will be leaving power on the table.

MAF scaling, as I detailed above should be used to address changes in the MAF or fuelling only, ie different MAF sensor, different injector size, slight changes to breathing etc

MAF scaling is for MAF scaling and not something more.

To buy the MoviChip ATF and to get more information on the ATF and to see it in action, click here


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