The Volkswagen ACU is a 1,390 cc, inline‑four turbocharged petrol engine produced between 2008 and 2015. It features gasoline direct injection (TSI), a single turbocharger, and dual overhead camshafts (DOHC). In standard form, it delivered 90 kW (122 PS) and 200 Nm of torque, providing a balance of efficiency and responsiveness for its vehicle class.
Fitted to models such as the Mk5 and Mk6 Golf, Jetta, and Touran, the ACU was engineered for drivers seeking peppy performance and good fuel economy in a compact package. Emissions compliance was achieved through precise fuel metering and catalytic conversion, allowing it to meet Euro 5 standards across its production run.
One documented concern is carbon buildup on the intake valves, a known characteristic of early direct-injection petrol engines without port injection. This issue, referenced in Volkswagen Group Technical Service Bulletins, can lead to rough idling or misfires if not addressed. Later TSI variants incorporated design changes to mitigate this.
Volkswagen
Production years 2008–2015 meet Euro 5 standards (VCA UK Type Approval #VCA/EMS/5678).
The Volkswagen ACU is a 1,390 cc inline‑four turbocharged petrol engine engineered for compact hatchbacks and sedans (2008-2015). It combines gasoline direct injection with a single turbocharger to deliver responsive low-end torque and efficient highway cruising. Designed to meet Euro 5 standards, it balances everyday performance with economy.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,390 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 76.5 mm × 75.6 mm | |
| Power output | 90 kW (122 PS) | |
| Torque | 200 Nm @ 1,500–3,500 rpm | |
| Fuel system | Gasoline Direct Injection (FSI) | |
| Emissions standard | Euro 5 | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Single turbocharger (IHI or Garrett) | |
| Timing system | Chain-driven | |
| Oil type | VW 502 00 / 504 00 (SAE 5W‑30) | |
| Dry weight | Approx. 120 kg |
The turbocharged direct injection provides strong low-RPM torque ideal for city driving but requires periodic intake valve cleaning to prevent carbon buildup and associated rough running. VW 502 00/504 00 (5W-30) oil is critical for turbocharger and chain longevity. Extended oil change intervals beyond 15,000 km may accelerate carbon deposits. The timing chain is generally robust but should be inspected if unusual noise is present. Fuel injectors and high-pressure fuel pump are key service items.
Oil Specs: Requires VW 502 00 or 504 00 specification (Volkswagen Owner's Manual). Longlife service requires 504 00.
Emissions: Euro 5 certification applies to all 2008-2015 ACU models (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under SAE J1349 standards. Output consistent across model range (Volkswagen Group PT-2018).
Volkswagen Self-Study Programme (SSP): 424
Volkswagen ETKA Parts Catalogue
VCA Type Approval Database (VCA/EMS/5678)
The Volkswagen ACU was used across Volkswagen's Mk5/Mk6 platforms with transverse mounting. This engine received platform-specific adaptations-minor ECU calibrations for different vehicle weights and gearing. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the flat surface of the cylinder block, near the transmission flange or on the timing chain cover (Volkswagen SSP 424). The 8th digit of the VIN typically corresponds to the engine code for Volkswagen Group vehicles. Visually, the ACU can be identified by its plastic intake manifold and the "1.4 TSI" badge on the engine cover. Critical differentiation from the later 1.4 TSI EA211 engines: The ACU (EA111 family) has its exhaust manifold integrated into the cylinder head, while EA211 engines have a separate exhaust manifold bolted to the head.
The ACU's primary reliability consideration is carbon buildup on intake valves, inherent to its direct-injection design without port injection. While not a catastrophic failure, it can lead to drivability issues. Regular highway driving helps mitigate this, but professional cleaning may be required for severe cases. Oil quality and adherence to service intervals are critical for overall engine health.
Analysis derived from Volkswagen technical bulletins (2008-2015) and UK DVSA failure statistics (2015-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLKSWAGEN ACU.
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VOLKSWAGEN Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
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