The accelerator must be pulled out when starting a cold engine, regardless of the ambient temperature. Only in severe frost can the engine start sometimes be faster if the accelerator handle is not pulled out.
After about a minute, the accelerator handle should be returned to its original position. However, if this does not happen, then the engine will not suffer. The launch accelerator performs the same function as the fuel injection advance clutch. Through the corresponding lever, the thrust of the accelerator acts on the piston of the ignition timing clutch, retracting it back. In this case, a proactive displacement of the pusher roller occurs by approximately 2.5°.
Pulling the cold start accelerator handle also causes a slight increase in idle speed. The combination of these two functions is carried out specifically to avoid the shaking of the power unit, which is characteristic of diesel engines when running in a cold state. The cold start accelerator handle can be pulled out a little if there is a need to individually increase the engine speed a little.
On vehicles with air conditioning, the idle speed increase device prevents the idle speed from dropping when the air conditioning compressor is turned on. At this moment, the membrane-type vacuum regulator moves the injection pump control lever in the direction «Full throttle». On cars manufactured before 1/92, the vacuum regulator is controlled by the idle speed increase relay located under No. 13 on the additional relay block on the left under the instrument panel. From 2/92 this relay is a component of the EGR control unit. Due to the increase in the size of the block, it is located in places 13 and 14 of the block of additional relays.
The high-pressure fuel pump is equipped with a vibration damper of the power unit, which prevents its increasing voltage when the accelerator pedal is pressed sharply. The need for such a shock absorber is dictated by a very «soft» suspension of the power unit. The vibration damper has a programmed play to allow the engine to rest on the correct foot when the accelerator pedal is depressed before the engine RPM is at full load. As a result, the buildup of the power unit on the suspension supports is excluded.
The vibration damper is supplemented with a so-called locking shock absorber, which prevents the power unit from swinging when the accelerator pedal is suddenly released. To do this, a small shock absorber is installed on the injection pump control shaft, which dampens the speed of movement of the lever, due to a sharp drop in the tension of the accelerator cable, and only then moves the lever (see illustration 3.0).
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