Symptoms

After starting a warm engine, a sudden drop in power during acceleration is noticeable. The engine works like a naturally aspirated diesel engine (without turbocharging effect). After exceeding the "threshold" speed for the first time (Ok. 3000 rpm), suddenly it unfolds at full strength again. Seems, that the fault is removed.

Cause – the drop in tension 'stuns” controller

Due to damaged battery or faulty contact (bad contact with mass, loose wire ends on the battery terminals), system voltage drops below 8 V. As a result, the EDC receives erroneous signals from the sprayer needle lift sensor and enters the emergency operation mode. Another possible cause is incorrect starting of the engine with an external source of energy and jumper cables, without surge protection (voltage spikes when disconnecting jumper cables)!

Troubleshooting and fault elimination

The fault memory can have "implausible signals" and "intermittent" faults from various sensors (air flow meter, engine speed sensor etc.). During the reading with the measuring value tester, one can find out, among other things,, that the size of the injected fuel doses is unchanged. Check the starting current of the battery under load (cooling state current) and electrolyte density. Measure the voltage during start-up. Additionally, check the alternator with a multimeter and oscilloscope. Voltage spikes caused by damaged windings or diodes lead to various faults being stored in the memory and to engine malfunctions while driving (and they can also destroy the driver). Otherwise, check that all mass connections are secure and clean, if necessary, bring it into working order. Be careful when starting with external energy sources: unsuitable jump leads or rectifiers (without protective capacitor) cause voltage spikes when connecting and disconnecting cables.