Mitsubishi 4J12 2.4L Engine Specs, Problems, Reliability, Info

Mitsubishi 2.4L 4J12 Engine Info

The Mitsubishi 4J12 is a 2.4-liter, naturally aspirated, gasoline inline four-cylinder engine produced since 2013 as an alternative to the 4B12 engine. The new 4J1 series features a SOHC valvetrain configuration with Variable Valve Lift (VVL) technology in addition to Mitsubishi Innovative Valve timing Electronic Control (MIVEC). Also, to meet stricter standards for CO2 emissions, these engines come with a start-stop system and more advanced exhaust gas recirculation (EGR). The 2.4L 4J12 engine was mostly used in compact crossover Mitsubishi Outlander on several markets, including Japan, North America, and Europe.

Mitsubishi 4J12 Engine Design

The 4J12 uses the same engine block as the 4B12. It is a die-cast aluminum open-deck cylinder block with cast iron liners, and it also comes with a balancing shaft module featuring an integrated oil pump. The main difference is on top. The engine has a new 16-valve die-cast aluminum cylinder head with a chain-driven single camshaft (SOHC). This head is equipped with variable valve timing and lift control (MIVEC and VVL). The valves are actuated by camshaft via rocker arms, rather than solid buckets, used on the 4B12. The 4J12 doesn't have hydraulic lifters (manual valve clearance adjustment required every 30-40,000 miles).

The engine uses a reliable, straightforward multi-point injection (MPI) system and electronic throttle body. On the intake side, there is a simple, fixed-geometry intake manifold made of plastic. The exhaust system comes with a stainless steel exhaust manifold. The 4J12 engine also comes with a modern electronic ignition system featuring individual coils and dual iridium spark plugs.

This engine kept almost the same output performance as a conventional 4B12 engine, while improving fuel economy and reducing emissions thanks to the VVL system and other minor tweaks. It delivers 169 hp at 6,000 rpm, 162 lb-ft (220 Nm) of torque at 4,200 rpm and averages about 24 to 26 MPG (9.0 to 9.8 liters per 100 km) in real-world combined driving.

Engine Specs

Mitsubishi 2.4L 4J12 Common Problems

This engine has a good reputation and is widely considered a robust and problem-free motor when properly maintained. But all engines have weaknesses, and 4J12 is no exception. Here is a short list of things you should be concerned about.

• The MIVEC and VVL systems require high-quality, clean oil. Poor oil or irregular oil changes can lead to sludge buildup and increased wear on components.
• The 4J12 engine does not have hydraulic lifters. It requires manual thermal valve clearance checks and adjustments roughly every 30-40k miles (50-70k km). Owners often forget to do this. If you hear rhythmic tapping or clicking noise from the top of the engine, it might be time to check the valve clearances. Too tight valve clearance can also be a reason for hard starting, rough idling or stalling.
• The timing chain often lasts only 100,000 miles. Its longevity highly depends on driving conditions and oil change intervals.

Reliability and Longevity

The Mitsubishi 4J12 2.4L engine is a good and reliable engine that can last up to 250,000 miles (400,000 km) with only regular maintenance. To squeeze maximum potential, it is necessary to use high-quality synthetic oil. Do oil changes at least every 4,500-6,000 miles (7,500-10,000 km) and always check and set valve clearances according to manufacturer recommendations.