Jerks in steady motion

Such jerks are most often caused by a malfunction of the ignition system. Diagnosis and repair needed (see sect. 10 «electrical equipment»). On the way, you can try to do the following yourself:

– Carefully inspect the engine compartment. Switch off the ignition and check the reliability of fastening and landing of all wires and connectors at the ignition coil and high-voltage wires. Start the engine and listen to its work: crackling during the breakdown of high voltage current on «mass» weak but distinct. In complete darkness, a spark is clearly visible during breakdown;

– Replace the spark plugs regardless of their condition and mileage. Pay attention to the condition of the candles: if it is not up to standard, it may be necessary to repair the engine or its systems.



A specific cause of jerks during the steady movement of a Ford Focus II vehicle may be the failure of the throttle position sensor built into the throttle assembly cover.

Additional symptoms confirming the malfunction of this sensor:

– Uneven work of the engine idling;

– reduction of the maximum power of the engine.

The throttle assembly cover is non-separable, so it is not repairable. If a sensor malfunction is detected (cm. «Check and replacement of gauges of a control system of the engine»), replace the throttle assembly with cover.