At the same speed and temperature, it obviously depends on the degree of opening of the throttle. Moreover, it depends on the speed of its opening: according to it, the controller recognizes the desire of the driver to accelerate smoothly or, on the contrary, to “shoot”. Depending on this, the system will keep the mixture stoichiometric or enrich to obtain increased torque.
The motor load from the point of view of the controller is also an electric parameter - RL. It is calculated as a percentage. (Do not confuse with mechanical loading - torque and power!) At minimum idle speed on a warm engine, this parameter is 18–23%, and on a non-rolled engine, including the “classic” and “Niva” families, up to 27– thirty%. Diagnostics working with a regular customer’s machine have a reason to fix the RL value in the computer - it may come in handy. As the new engine is run-in, the parameter gradually decreases due to a decrease in mechanical losses. But a sudden drop in interest by fifteen - a sure sign that the engine receives air bypassing the air intake manifold - look for a place to leak! Increased resistance to rotation of the rotor of the generator or pump increases the load. But it (formally) increases with a malfunction of the DMRV. Full load corresponds to RL = 75%.
And what happens when air density changes, for example, on mountain roads, where air pressure drops with a climb? As you know, the cylinders are filled in accordance with their volume, and the mass of rarefied air that gets into them with a height is less, the higher you climbed. If you focus only on temperature, speed or the degree of opening of the throttle, the nozzles will work at high altitude, as at sea level - the composition of the mixture will be richer. Particularly difficult to start the engine - re-enriched mixture from the spark does not ignite. By the way, for connoisseurs: do not confuse this situation with the carburetor - there the flow of fuel into the diffuser depends on the pressure difference between the diffuser and the outside air - and the issue with the composition is more complicated. The controller takes into account the height, “logically” reducing the opening time of the nozzles. Altitude correction factor - FHO. This is the ratio of the engine load at the current height to the load when it is operating at sea level (of course, ceteris paribus - the road is horizontal, speed, temperature, etc. are the same). For every 1000 m of extra height, the FHO decreases by 0.1. This accuracy is quite enough, because cars rarely climb above 5000 m! If in St. Petersburg the factor is equal to unity, then at the foot of Elbrus it is about 0.8. The controller calculates the FHO only in motion.
The next important indicator is the nozzle open state time (photo 1) in milliseconds - TI. On engines with phased injection, the nozzle fires once every two crankshaft turns when the intake valve is open. The pulse duration is about 4 ms. On obsolete systems with simultaneous and pairwise parallel injection, the nozzle works twice in one working cycle, but the pulse is twice as short. It’s important not to confuse these things - you see, you don’t have to study the reaction of the system to the supposedly dirty nozzle!
When the machine brakes with the engine, the controller, taking into account the number of revolutions of the crankshaft and the speed, reduces or completely cuts off the fuel supply. In the first case, TI is not equal to zero. The BSA parameter allows you to make sure that the fuel supply is turned off: it takes only one of two possible values - is there a fuel cut-off or not.
The purpose of the idle speed controller (photo 2) is obvious from the name. In particular, it maintains optimal crankshaft speed when the engine warms up. The movement of its MOMPOS stock is specified in steps. Full stroke - 255 steps. Countdown - from the closed position. Until the engine warms up, at idle, the stem is 50–100 steps from the closed position. At operating temperature, it moves to the position of 25-50 steps, reducing air flow through the idle channel. We emphasize: the regulator is constantly involved in the operation of the engine, reacts even to small changes in the mode - due to the inclusion of lighting fixtures, rear window heating, etc. In addition, the regulator helps to reduce the toxicity of exhaust gases in the forced idle mode: when the throttle is closed abruptly, the regulator increases the air flow bypassing the damper, preventing at least a short re-enrichment of the mixture.
The scanner has the function of checking the actuators, which include the idle speed controller. Its performance is evaluated by setting the movement of the rod and monitoring the changing speed of the crankshaft.
Many people successfully evaluate engine noise by ear. But this is the old fashioned way. There is a parameter RKRN - the normalized signal level from the knock sensor (photo 3), measured in volts: at the minimum idle speed of a working engine it is 0.3–1.0 V. When worn, for example, the guide bushings will be higher. The specialist in engine diagnostics must know these subtleties.
Today's stringent requirements imply not only exhaust gas toxicity control. Remember at least the reason for the appearance of asbestos-free brake pads! Today, it is necessary to drastically limit the evaporation of fuel from the power system. No gas stink! And it's not just about preventing direct fuel leaks. Its vapors from the tank enter the adsorber (activated carbon container), and from there into the intake manifold. The adsorber is purged with air, and the controller controls the process, changing the time for opening the purge valve as necessary. If the car is standing with the engine running, the valve is audible (tapping in the engine compartment, some are alarming).
The operation of this subsystem is evaluated by the TATEOUT parameter - the duty cycle of the adsorber purge signal. The parameter is calculated as a percentage.
The purge valve is also an actuator (photo 4). Check it with a scanner. For example, we increase the valve opening time (TATEOUT is growing) and at the same time we monitor the MOMPOS parameter - the position of the idle speed control needle. If the number of steps decreases, it means that the controller took into account additional (purge) air with fuel vapors coming from the adsorber. It turns out that the valve is operational, knocking for good reason.