Misfires and an unstable idle on the 1.4/1.6 MPI (K7J/K7M): a cracked ignition coil and the idle stepper motor

Engine / equipment

1.4 MPI (K7J) and 1.6 MPI 8V (K7M), petrol or LPG: Dacia Logan I, Logan MCV I and Sandero I

Period mentioned

2004–2013

Symptoms

The engine shakes or runs on three cylinders, above all in damp weather or when cold, and the OBD scan shows misfires; or the idle will not hold: the engine stays revving or stalls when you stop.

Possible cause described

According to the owners who answer on DailyDriven, the ignition coil cracks and stops sparking in damp weather (a 1.4, and a 1.6 that twice failed to start at 230,000 km), and the idle stepper motor (idle valve) fails: on one 1.4 it was replaced three times from about 35,000 km, and on another the engine stayed revving at 235,000 km. These are owner reports, not statistics.

Check for the garage

Read the codes with an OBD reader and check the coil for cracks, together with the spark plugs and leads; if the idle fails, clean or test the stepper motor before replacing other parts. On LPG cars a weak coil shows up first when running on gas.

Cost cited in the source

What DailyDriven owners paid: a coil, about 100 lei; a set of spark plug boots, 97 lei; cleaning the stepper motor, 50 lei of products. Amounts in lei from earlier years, not a current quote.A rough figure from the original database, not an up-to-date quote.

Sources from the original database