Fiat E.torQ

Fiat's 1.6 and 1.8 litre petrol four, built in Brazil and developed from the Tritec engine that Chrysler and BMW had jointly produced for the first-generation MINI — an unusual lineage that puts a distant MINI relative under a Jeep Renegade.

It is a chain-driven, port-injected engine designed for the South American market, where most versions run as flex-fuel on petrol, ethanol or any mixture of the two. That is the diagnostically significant fact: fuel trims, cold-start behaviour and injector duty all vary with what is in the tank, and a fuel-trim reading interpreted as though the engine were running petrol can point at a fault that is not there.

Its complaints are ordinary — coils, sensors, throttle-body carbon — with ethanol's known effect on fuel-system components at high mileage as the addition. Independent documentation outside Brazil is thin, which is exactly the gap a community node addresses.