Electronic Solutions for Motorsport

MAF Tuning – Pluses and Minuses

3 min read
MAF curve

MAF Tuning & Scaling

MAF tuning is a fast, easy and effective way to alter the fuelling of your engine but with some provisos

MAF tuning should only be used to fine tune the fueling of your car. If you are having to make big adjustments to your fueling, more than 10-20% you may want to look at a solution that controls the fuel injectors rather than the MAF sensor

How can MAF tuning be bad?

The MAF sensor tells the engine exactly how much air is going in. The amount of air entering the engine effects the fueling but it also effects the ignition timing.

The more densely packed the air is in your combustion chamber the shorter it take for the mixture to ignite in short, you need less ignition timing the fuller the combustion chamber is.

The converse is also true, low density air:fuel mixtures in your combustion chamber, eg high RPM low throttle, take longer to produce maximum pressure after the spark plug has been fired. This means the engine needs more spark advance, more ignition timing

So hopefully my explanation makes it clear how MAF tuning effects not only the fuel injected but also the ignition timing.

When we tune the MAF sensor we could be telling the engine a different story to reality and the car’s ECU is going to base ignition timing based on the manipulated figures.

This can be good and bad, MAF tuning has its pluses and minuses. Depending on the reason you are tuning your MAF sensor you could also need to advance your ignition timing but the way you are tuning the MAF signal is retarding the ignition.

For example

You have fitted bigger injectors. You will need to reduce the MAF signal so the ECU injects less fuel, this advances the ignition timing, because the ECU thinks the air:fuel mixture is less dense. In reality the air:fuel ratio is actually the same as before after tuning the MAF signal but now you are also running less ignition advance. Depending on your other modifications this could mean your engine is making less power.

The opposite would be true if you fitted a larger MAF sensor. Now you would be increasing the MAF signal going to the ECU, ignition timing would increase, even though the air:fuel ratio could be the same. Advancing the timing could be something you wanted to do anyway but maybe it isn’t if you were already at the knock limit for the engine

These are two examples of the knock on effects of MAF tuning and this is why we say MAF tuning is good for fine tuning but not for making big changes. (If you are altering ignition timing with a separate device then these points will be mute)

MAF tuning is a fast an effective way of changing fuelling but you need to be aware of the consequences, ie the knock on effects it has. The knock on effects will depending what modifications you have done to your engine and what you want to achieve, what things you want to change.

MoviChip sells a maf tuning device called the AutoMAF, it automatically tunes the MAF signal as you drive. Click here for more information

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