Yeah, so much for the &quot;reverse engineering&quot; operation. The guy didn&#x27;t even take the time to research what the A2L is, but he was quick to throw accusations around [1]. There&#x27;s nothing like some quick internet exposure.<p>[1] &quot;Domke said that it is clear that lots of different kinds of cheating is going on in the ECU&quot; ... because &quot;12KB block of code that is used to ensure the tachometer always shows 780 RPM when the car is idling. Even though the engine is not that steady [...]&quot;. What does he expect? The RPM niddle to have 1-2-10 rpm resolution on the analog board? Or for the value to switch super fast on the digital screen to annoy the driver? All this stuff is filtered to have a smooth display info on the dashboard, same way input values from sensor in all sensor based applications are filtered at some point, for example.<p>[edit]<p>And btw, the SW is not set to display anything. The engine ECU does not display shit. It send data to the BCM or some other module over the CAN (usually) network.
The value of 780 rpm in this case is a setpoint value. The ECU is programmed to KEEP a minimum idle engine speed value when not torque is requested. Else the engine would stall. This is done in a closed loop, one of the inputs being the engine speed which is calculated in different ways, from system to system (usually crank wheel sensor counting the teeth). This balance you may imagine will not be able to keep perfectly fixed 780 rpm idle speed, while the BCM will filter the dashboard value for driver&#x27;s comfort.