Mitsubishi 4B1

Mitsubishi's 1.8 to 2.4 litre petrol four — part of the Global Engine Alliance design shared with Chrysler and Hyundai, which is why its architecture resembles the Chrysler World Engine and why parts commonality is broader than the badge suggests. It powers the Lancer, Outlander and ASX, and in turbocharged 4B11T form the Lancer Evolution X.

It is an aluminium, chain-driven design with MIVEC variable valve timing. In naturally aspirated form it is undramatic: the recurring items are the MIVEC actuator and its oil control solenoid, which respond to oil condition and set timing codes, plus the usual ignition and sensor wear.

As with much of Mitsubishi's range, a large share of these cars use a CVT, and complaints described as engine hesitation or flaring are frequently transmission behaviour. Separate an engine-speed symptom from a road-speed one before diagnosing, because the two are routinely conflated on these vehicles.