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Calculating load based on TPS or MAP

EFI Tuning Fundamentals

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could you please tell me, how does ECU know the amount of air entering the engine when measuring TPS or MAP values?

Despite all the downsides of using MAF, it tells ECU if you go on full throttle when standing still and a small amount of air is being sucked in or if you go on full throttle when driving 100km/h with 5th gear and big amount of air is used.

TPS or MAP values are same in both of these two cases, so how is the amount of air entering the engine calculated?

Please tell me if I am wrong.


By multiplying by the displacement of the engine in one cycle. The only thing that makes it a "big amount of air", is the rate at which the cycle occurs (engine speed). We are injecting fuel per cylinder / per cycle with most ECUs.

Thank you for the answer, but I still don’t get it.

I can hit the 7000rpm rev limiter while standing still, or I can hit it on full speed with 5th gear. Amounts of entering air will be different, or am I wrong?

While different, they are very similar. The difference is the volumetric efficiency, which does vary by the load (ie, Manifold Pressure required to maintain that RPM). The Manifold Pressure is changed by the Throttle Position).