The Jaguar AJ28 is a 4,196 cc, V8 petrol engine produced between 1998 and 2009. It belongs to Jaguar's AJ-V8 family, featuring double overhead camshafts (DOHC), 32-valve configuration, and sequential multi-point fuel injection. In standard calibration, it produces 220 kW (299 PS) and 400 Nm of torque, delivering smooth power delivery with strong mid-range responsiveness for grand touring applications.
Fitted primarily to the XJ (X308/X350) and XK (X100) models, the AJ28 engine was engineered to provide refined performance and cabin quietness. Emissions compliance was achieved through a three-way catalytic converter and closed-loop lambda control, enabling Euro 3 and later Euro 4 certification depending on model year and market. Its all-aluminium construction contributed to weight savings while maintaining structural rigidity.
One documented concern is degradation of the inlet manifold swirl flap actuators, which can result in flap detachment and potential engine damage. This issue is referenced in Jaguar Service Bulletin JTSB-06-21-04. From 2003, revised actuator design and updated ECU mapping were introduced to improve reliability and reduce carbon buildup.
Jaguar
Production years 1998–2002 meet Euro 3 standards; 2003–2009 models comply with Euro 4 (VCA UK Type Approval #VCA/EMS/5432).
The Jaguar AJ28 is a 4,196 cc V8 petrol engine developed for luxury sedan and grand tourer platforms (1998–2009). It features DOHC architecture with four valves per cylinder and sequential fuel injection to ensure smooth power delivery. Designed initially for Euro 3 and later upgraded to Euro 4 emissions standards, it balances refinement with adequate performance for its era.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 4,196 cc | |
| Fuel type | Petrol | |
| Configuration | V8, DOHC, 32-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 89.0 mm × 84.0 mm | |
| Power output | 220 kW (299 PS) @ 6,150 rpm | |
| Torque | 400 Nm @ 4,100 rpm | |
| Fuel system | Sequential multi-point fuel injection (Siemens MS43) | |
| Emissions standard | Euro 3 (pre-2003); Euro 4 (2003–2009) | |
| Compression ratio | 10.7:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain-driven (dual-row primary, single-row secondary) | |
| Oil type | Jaguar Approved SAE 10W-40 (WSS-M2C159-C) | |
| Dry weight | 205 kg |
The naturally aspirated V8 provides smooth, linear power ideal for relaxed cruising but requires adherence to 12,000 km oil change intervals to maintain hydraulic tappet and timing chain longevity. Jaguar-approved 10W-40 oil meeting WSS-M2C159-C specification is essential for maintaining valve train stability and preventing premature camshaft wear. Extended idling or short-trip driving may accelerate carbon buildup on intake valves and swirl flaps due to lack of cleaning effect from direct injection. The Siemens MS43 fuel system is sensitive to fuel quality, necessitating use of premium unleaded (RON 95+) and periodic inspection of swirl flap actuators. Post-2003 models feature updated actuator design and ECU calibration per Jaguar SIB JTSB-06-21-04.
Oil Specs: Requires Jaguar WSS-M2C159-C (10W-40) specification (Jaguar SIB JTSB-09-23-05). Supersedes ACEA A3/B4.
Emissions: Euro 4 certification applies to 2003–2009 models only (VCA Type Approval #VCA/EMS/5432). Pre-2003 models meet Euro 3.
Power Ratings: Measured under ISO 1585 standards. Full output requires RON 95+ fuel (Jaguar PTS-4213).
Jaguar Technical Information System (TIS): Docs A42008, JTSB-06-21-04, JTSB-09-23-05
VCA Type Approval Database (VCA/EMS/5432)
ISO International: ISO 1585 Road vehicles — Test method for fuel consumption
The Jaguar AJ28 was used across Jaguar's X308/X350 platforms with longitudinal mounting and shared architecture with Daimler for select applications. This engine received platform-specific tuning-shortened intake runners in the XK and revised exhaust manifolds in the XJ-and from 2003 the facelifted XJ Series III adopted updated ECU mapping and swirl flap design, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side cylinder block near the exhaust manifold (Jaguar TIS A42008). The 8th VIN digit indicates engine type ('R' for 4.2L V8 petrol). Pre-2003 models have red valve covers with chrome accents; post-2003 units use dark grey valve covers. Critical differentiation from supercharged variants: AJ28 has no belt-driven supercharger and uses a naturally aspirated intake manifold. Service parts require model year verification—swirl flap actuators for pre-2003 models are incompatible with post-update units due to mechanical redesign (Jaguar SIB JTSB-06-21-04).
The AJ28's primary reliability risk is inlet manifold swirl flap failure, with elevated incidence in high-mileage vehicles. Jaguar internal field reports from 2007 indicated a measurable number of pre-2003 units requiring manifold replacement before 120,000 km, while UK DVSA MOT data shows increased emissions-related failures linked to lambda sensor faults. Urban driving cycles and poor fuel quality amplify carbon buildup, making actuator inspection and fuel quality adherence critical.
Analysis derived from Jaguar technical bulletins (1998–2009) and UK DVSA failure statistics (2010–2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about JAGUAR AJ28.
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DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
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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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