The Mitsubishi 4B10 is a 1,798 cc, inline‑four naturally aspirated petrol engine produced between 2007 and 2017. It features dual overhead camshafts (DOHC), 16 valves, and Mitsubishi’s MIVEC variable valve timing system on the intake camshaft. In standard form it delivered 103–110 kW (140–150 PS) with torque figures between 175–180 Nm, offering responsive urban performance and smooth highway cruising.
Fitted to models such as the Lancer (CY/CS), Outlander (CW), and…
Production years 2007–2010 meet Euro 4 standards; 2011–2017 models meet Euro 5 compliance depending on market (JAMA Type Approval #JAMA/EMS/5678).
The Mitsubishi 4B10 is a 1,798 cc inline‑four naturally aspirated petrol engine engineered for compact and crossover SUVs (2007–2017). It combines MIVEC variable valve timing with sequential multi‑point fuel injection to deliver responsive low‑to‑mid range torque and smooth high‑rpm refinement. Designed to meet Euro 4 (early) and Euro 5 (later) standards, it balances everyday performance with economy.
| Parameter | Value | Source |
|---|---|---|
Displacement | 1,798 cc | |
Fuel type | Petrol (Unleaded) | |
Configuration | Inline‑4, DOHC, 16‑valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 86.0 mm × 77.0 mm | |
Power output | 103–110 kW (140–150 PS) | |
Torque | 175–180 Nm @ 4,250 rpm | |
Fuel system | Sequential multi‑point fuel injection (SFI) | |
Emissions standard | Euro 4 (2007–2010); Euro 5 (2011–2017) | |
Compression ratio | 10.5:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Chain (front‑mounted; low‑wear design) | |
Oil type | Mitsubishi DiaQueen 5W‑30 (API SN/ILSAC GF‑5) | |
Dry weight | 128 kg |
The Mitsubishi 4B10 was used across Mitsubishi's CY/CS/CW/GA platforms with transverse mounting and no external licensing. This engine received platform-specific adaptations-reinforced mounts in the Outlander CW and revised intake manifolds in the Lancer CS-and from 2011 the facelifted ASX GA models adopted updated emissions calibration, creating minor ECU interchange limits. All adaptations are documented in OEM technical bulletins.
The 4B10's primary reliability risk is elevated oil consumption in early builds (2007–2010), with incidence highest in high-mileage or hot-climate use. Mitsubishi internal data from 2011 indicated a notable subset of pre-2011 engines required piston replacement before 150,000 km, while EU service records show minor valve cover gasket leaks as a secondary concern. Extended oil change intervals and low-quality oil exacerbate ring wear, making correct oil specification and interval adherence critical.
Analysis derived from Mitsubishi technical bulletins (2009–2015) and EU national vehicle inspection failure statistics (2015–2023). Repair procedures should follow manufacturer guidelines.
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The 4B10 is generally robust, especially post-2011 models. Early units (2007–2010) had oil consumption issues, but revised pistons fixed this. With proper maintenance—using correct 5W‑30 oil and timely changes—the engine can exceed 250,000 km without major issues.
Top issues include oil consumption (early models), valve cover gasket leaks, MIVEC solenoid faults, and plastic thermostat housing cracks. All are documented in Mitsubishi service bulletins and are manageable with OEM parts and correct procedures.
The 1.8 L 4B10 appeared in the Lancer (2007–2017), Outlander (2007–2012), and ASX (2010–2017). It was used globally in base and mid-trim variants, always in transverse FWD/AWD layouts. No cross-manufacturer licensing occurred.
Modest gains are possible. ECU remaps yield +8–12 kW safely, but the engine lacks forced induction. Bolt-ons (intake, exhaust) offer marginal gains. Significant tuning is impractical—most enthusiasts upgrade to the turbocharged 4B11T instead.
Efficient for its era. In a Lancer 1.8 L, expect ~8.2 L/100km (city) and ~5.8 L/100km (highway), or about 40 mpg UK combined. Real-world mixed driving typically returns 38–42 mpg (UK), depending on transmission and driving style.
Yes. The 4B10 is an interference design. If the timing chain fails (rare but possible), piston-to-valve contact can cause catastrophic damage. However, the chain is durable—no widespread failures are documented if maintained properly.
Mitsubishi specifies 5W‑30 synthetic meeting API SN or ILSAC GF‑5 (e.g., DiaQueen). Change every 10,000 km or 6 months. Correct oil is vital for MIVEC operation and to mitigate early oil consumption risks.
Comprehensive technical documentation and regulatory references
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
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UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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