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Toyota AZ engine
Toyota AZ engine
Toyota AZ engine
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Toyota AZ engine
2AZ-FE engine
Overview
ManufacturerToyota Motor Corporation
Production2000–2019
Layout
ConfigurationStraight-4
Displacement2.0 L (1,998 cc)
2.4 L (2,362 cc)
Cylinder bore86 mm (3.39 in)
88.5 mm (3.48 in)
Piston stroke86 mm (3.39 in)
96 mm (3.78 in)
Cylinder block materialAluminium
Cylinder head materialAluminium
ValvetrainDOHC 4 valves x cyl. with VVT-i
Compression ratio9.6:1, 9.8:1, 11.0:1, 12.5:1
RPM range
Max. engine speed6500
Combustion
SuperchargerTRD (on 1st gen Scion tC and 2nd gen xB only)
Fuel systemSequential MPFI
D-4 direct injection
Fuel typeGasoline
Cooling systemWater-cooled
Output
Power output145–240 hp (108–179 kW)
Torque output190–325 N⋅m (140–240 lb⋅ft)
Dimensions
Length626 mm (24.6 in)
Width608 mm (23.9 in)
Height681 mm (26.8 in)
Chronology
PredecessorToyota S engine
SuccessorToyota AR engine

The Toyota AZ engine family is a straight-4 piston engine series. The AZ series uses an aluminium engine block with cast iron cylinder liners and aluminium DOHC cylinder head. The engine series features many advanced technologies including slant-squish combustion chambers, offset cylinder and crank centers, and the VVT-i continuously variable intake valve timing system. The aluminium engine measures 626 mm (24.6 in) long, 608 mm (23.9 in) wide, and 681 mm (26.8 in) tall.

The cylinder block is an open-deck, midi-skirt die-cast aluminium type with cast-in iron liners and a die-cast aluminium lower crankcase and a stamped oil pan. The forged steel crankshaft is fully balanced with eight counterweights and supported by five main bearings. A helical gear pressed in No. 3 counterweight drives twin contra-rotating balance shafts in the shaft housing within the lower crankcase.

The dual overhead camshafts are driven by a single-stage roller chain of 8 mm (0.31 in) pitch, enabling a narrow included valve angle of 27.5°. The camshafts act on four valves per cylinder via bucket tappets. As in the recent Toyota engine practice, no clearance adjusting shim is employed. Valve diameters are 34 mm (1.3 in) for intake and 29.5 mm (1.16 in) for exhaust, with 8 mm (0.31 in) lift for both intake and exhaust. The four-vane VVT-i device is fitted on the intake camshaft, altering timing by 50°. The valve cover is made of magnesium to save weight.

Fuel is injected sequentially via an ultra-fine-atomization injector with twelve small injection holes, each 0.18 mm (0.0071 in) in diameter. As in the smaller NZ engine, the new AZ adopts a plastic, built-up, and vibration-welded intake manifold integrating a large volume plenum chamber (3.5 L (210 cu in) volume including a 1.3 L (79 cu in) resonator). Exhaust manifolds are of tubular construction with integrated catalytic converters.

The AZ is the replacement for the S engine. Its successor is the AR engine.

Excessive oil consumption

[edit]

The 2AZ-FE engine in the 2007-2009 Camry and 2006-2009 Rav4 may burn excessive oil and is involved in a lawsuit. Other engines are also affected.[1]

Toyota service will perform a free oil consumption test to determine if the engine is affected. To qualify, all of the following must apply:

  • Burning more than 1 US quart (946 ml) of oil in 1,200 miles (1,931 km)
  • Has less than 150,000 miles (241,402 km)
  • Is less than 10 years old
  • Is located in the U.S.

There are approximately 1,715,200 vehicles covered by this Warranty Enhancement Program. A similar campaign are also done in Japan by Toyota in 2014.[2]

1AZ

[edit]

The 1AZ line of engines have 2.0 L (1,998 cc) of displacement.

1AZ-FE

[edit]

The 1AZ-FE is a 2.0 L (1,998 cc) version. Output is 108 kW (145 hp) at 6000 rpm with 190 N⋅m (140 lb⋅ft) of torque at 4000 rpm for the Camry Aurion version. Rav4 and Ipsum engines were rated at 148–150 hp (110–112 kW) at 6000 rpm and 142 lb⋅ft (193 N⋅m) of torque at 4000 rpm.

The 1AZ has a total displacement of 2.0 L (1,998 cc) with 86 mm × 86 mm (3.39 in × 3.39 in) bore and stroke, and a compression ratio of 9.6:1.

Applications:

1AZ-FSE

[edit]

The 1AZ-FSE is a 2.0 L (1,998 cc) version. Bore and stroke is 86 mm × 86 mm (3.39 in × 3.39 in), and a compression ratio of 11.0:1. Output is 149 PS (110 kW; 147 hp) at 5700 rpm with 196 N⋅m (145 lb⋅ft) of torque at 4000 rpm. The 1AZ-FSE features Toyota's D-4 direct injection system.

Applications:

2AZ

[edit]

The 2AZ line of engines have 2.4 L (2,362 cc) of displacement.

2AZ-FE

[edit]

The 2AZ-FE is a 2.4 L (2,362 cc) version built in Japan (Kamigo Plant and by Toyota Industries Corporation), at TMMK in the USA and also built in China for select Scion xB models, and also in Australia, obtains a total displacement of 2.4 L (2,362 cc) with 88.5 mm × 96 mm (3.48 in × 3.78 in) bore and stroke, with a compression ratio of 9.6:1. Output is 160 hp (119 kW) at 5600 rpm; 220 N⋅m (162 lb⋅ft) of torque at 4000 rpm.

Later versions of the 2AZ-FE engine were upgraded with 9.8:1 compression ratio, a slightly more aggressive intake cam profile, 6500 rpm redline, and piston oil squirters. These later versions are rated at 161 hp (120 kW) in the Scion tC, 177 hp (132 kW) in the RAV4, and 158 hp (118 kW) in the Camry, Corolla XRS, Scion xB, and 177 hp (132 kW) for the Previa/Estima/Alphard.

Photo of the 2AZ-FE engine used in a Toyota RAV4 2007

Some Japan-made Toyota vehicles with the 2AZ-FE engine were equipped with the K112 transmission also referred to as 7-speed Super CVT-i automatic (Seven-speed Sequential Shiftmatic) from October 2005.[3]

However, these later 2AZ-FE models were the first to be rated under the new SAE J1349 standard.[citation needed] The new standard usually produces more conservative numbers, though no definitive comparison is available since the two versions were never tested by the same standard. The RAV4 uses a different timing chain cover from the Camry, they can however be interchanged.[citation needed]

A TRD supercharger was available for the Scion tC and 2nd generation xB until Spring 2009.

There have been complaints of this engine "burning oil" in North America from the 2006 model year onwards,[4] with the issue starting after 45,000 miles (72,000 km), though mostly after 60,000–75,000 miles (97,000–121,000 km). Piston ring design has been identified as a potential problem. Toyota has issued a TSB (Technical service bulletin) TSB #0094-11 in August 2011 but has not issued a recall. Alternative theories point to a head gasket problem: the 2AZ-FE aluminum block threads may wear out on the back three middle bolts (closest to firewall).[citation needed] Check TSB SB-0015-11.

There are several class-action lawsuits underway regarding this issue. In January 2015, Toyota North America issued extended warranty notification (ZE7) for this issue for Toyota North America vehicles only.

Applications:

2AZ-FSE

[edit]

The 2AZ-FSE is a 2.4 L (2,362 cc) version. Bore and stroke is 88.5 mm × 96 mm (3.48 in × 3.78 in), and a compression ratio of 11.0:1. Output is 163 PS (120 kW; 161 hp) at 5800 rpm with 231 N⋅m (170 lb⋅ft) of torque at 3800 rpm. The 2AZ-FSE features Toyota's D-4 direct injection system.

Applications:

2AZ-FXE

[edit]

The 2AZ-FXE is an Atkinson cycle variant of the 2AZ-FE. It has the same bore and stroke, but the intake cam and pistons are unique. It has a physical compression ratio of 12.5:1.

The longer than normal open intake valve duration leads to a reduction in cylinder charge and reduced torque and power output, but efficiency is increased. This combination makes the 2AZ-FXE suitable for use only in hybrid vehicles, where peak torque and power demands can be met by the electric motor and battery.

Maximum output when used in the Camry hybrid is 187 hp (139 kW; 190 PS) at 6000 rpm with 257 N⋅m (190 lb⋅ft) of torque at 4400 rpm.

Applications:

3AZ

[edit]

The 3AZ line of engines have 2.4 L (2,362 cc) of displacement.

3AZ-FXE

[edit]

The 3AZ-FXE is an Atkinson cycle engine which is always paired to an electric motor in a hybrid system. This engine is an analogue of the 2AZ-FXE which is for the Chinese market only.[5]

Applications:
* 2010 Toyota Camry Hybrid AHV40 (China)

See also

[edit]
Wikimedia Commons has media related to Toyota AZ engines.

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Toyota AZ engine

View on Grokipedia
from Grokipedia
The Toyota AZ engine family is a series of inline-four DOHC engines produced by Motor Corporation, introduced in 2000 as a successor to the S engine series, characterized by an aluminum alloy block with cast iron cylinder liners, aluminum cylinder heads, and chain-driven valvetrains. The family primarily consists of two main displacements: the 2.0-liter 1AZ-FE and the 2.4-liter 2AZ-FE, with additional variants such as direct-injection FSE models, offering a balance of power, , and lightweight construction for mid-size vehicles. Key features of the AZ engines include Toyota's Variable Valve Timing-intelligent () system for optimized performance across RPM ranges, electronic fuel injection, and a typically around 9.6:1 to 10.0:1, enabling outputs from approximately 145 hp and 137 lb-ft of in base 1AZ-FE versions to 170 hp and 163 lb-ft in higher-tune 2AZ-FE configurations. These engines were designed for broad application in front-wheel-drive and all-wheel-drive platforms, powering popular models such as the , Avensis, RAV4, Highlander, and Matrix from 2000 to 2019, before being phased out in favor of the newer AR series. Renowned for their durability and low maintenance needs, AZ engines generally achieve 180,000 to 250,000 miles of service life with routine care, though early production units (particularly pre-2006 2AZ-FE models) are prone to specific issues like excessive oil consumption due to wear and occasional head bolt failures leading to problems. Later revisions addressed these concerns through improved materials and , enhancing overall reliability and contributing to the engines' reputation in the for cost-effective, efficient propulsion in everyday vehicles.

Overview

Description and Role

The Toyota AZ engine family comprises a series of inline-four (straight-4) dual overhead (DOHC) engines with displacements ranging from 2.0 liters to 2.4 liters. These engines utilize an aluminum block with liners and aluminum DOHC heads, contributing to reduced overall weight compared to predecessors. Introduced in , the AZ series was developed as mid-size powerplants to replace the older S-series engines, becoming a core component in Toyota's lineup for over a decade. They powered a variety of vehicles, including compact and mid-size sedans, s, minivans, and later hybrid models, such as the 2AZ-FXE in the 2003 Alphard Hybrid. Notable initial applications included the 1AZ-FE variant in the sedan and RAV4 . Key family characteristics emphasize efficiency and versatility, featuring for optimized performance and fuel economy, alongside aluminum construction that aids in weight savings. The design also supports adaptability to both conventional drivetrains and hybrid systems, as seen in variants like the 2AZ-FXE used in models such as the Camry Hybrid.

Production History

The Toyota AZ engine family was introduced in February 2000 at the Kamigo Plant in , marking Toyota's transition from the heavier cast-iron S-series engines to lighter, more fuel-efficient aluminum-block designs aimed at improving vehicle performance and meeting evolving environmental standards. This shift supported broader corporate goals for reduced weight and enhanced efficiency in mid-size applications. Key milestones included the debut of the 1AZ-FE variant in 2000, followed by expansion into hybrid applications with the 2AZ-FXE engine in the Alphard Hybrid in 2003. Production of hybrid variants continued to grow, powering models like the Camry Hybrid from 2007 onward. Most AZ variants ceased production around 2014, though select 2AZ-FE applications persisted until 2018 in certain markets. Manufacturing occurred primarily at Toyota's Kamigo and Shimoyama plants in , with additional assembly in for regional Camry production starting in the early and in at the Guangqi Toyota Engine facility from 2005. These sites enabled global supply chains for vehicles such as the RAV4 and Highlander. The AZ series was gradually phased out starting around 2008–2010, replaced by the AR series for port-injected FE variants and the ZR series for direct-injection FSE models, driven by increasingly stringent global emissions regulations and Corporate Average Fuel Economy (CAFE) requirements. Cumulative production exceeded 10 million units by May 2004, reflecting its widespread adoption across Toyota's lineup.

Design Features

Core Architecture

The Toyota AZ engine family utilizes a die-cast aluminum of open-deck , incorporating thin cast-iron liners fused into the aluminum structure to enhance durability, reduce weight, and improve heat dissipation. These liners provide robust wall integrity while maintaining the lightweight benefits of aluminum construction essential for transverse mounting in compact vehicles. Bore diameters across the series vary from 86 mm to 88.5 mm, paired with stroke lengths of 86 mm to 96 mm, yielding displacements ranging from 2.0 L (1,998 cc) in the 1AZ variants to 2.4 L (2,362 cc) in the 2AZ and 3AZ configurations. This modular approach allows scalability within the family while preserving core structural consistency. Pistons are made from lightweight aluminum alloy with a shortened skirt design and friction-reducing polymer coating, complemented by low-tension rings that lower internal drag for better . The crankshaft consists of forged , fully balanced with eight counterweights and supported by five main bearings to minimize vibrations and ensure reliable high-rpm performance. Lubrication is handled via a wet-sump system with a chain-driven trochoidal oil pump that provides pressurized oil flow through an external filter, while certain applications include an integrated oil cooler to manage temperatures during extended operation. Compression ratios are generally set at 9.8:1 to 10.0:1 for standard variants to balance power and efficiency, around 12.5:1 in hybrid models utilizing the for enhanced efficiency.

Valvetrain and Timing

The Toyota AZ engine employs a double overhead (DOHC) configuration with 16 arranged in a 4--per-cylinder layout, utilizing direct-acting mechanical tappets for actuation. This design minimizes friction and noise while providing precise control. The timing system features a single-row drive for the , paired with an automatic hydraulic to maintain proper tension and reduce wear. Engineered for durability, the timing chain is designed to achieve a exceeding 200,000 km under normal operating conditions with regular oil changes and . All AZ engines incorporate Toyota's Variable Valve Timing with intelligence (VVT-i) system on the intake camshaft, which hydraulically adjusts intake valve phasing relative to the crankshaft by a range of 40–60 degrees to enhance low-end torque, mid-range power, and fuel efficiency across the RPM spectrum. This technology contributes to improved performance in applications such as the Camry, where it supports better overall economy without compromising drivability. The is generally of an interference design, though the robust and setup minimizes risks; however, chain stretch may occur after approximately 150,000 km, potentially requiring inspection or replacement to prevent timing issues.

Fuel and Emission Systems

The Toyota AZ engine family primarily employs a multi-point electronic (MPI) system with sequential injection, delivering to each individually for optimized efficiency and reduced emissions. This base system is paired with coil-on-plug ignition, where individual ignition coils mounted directly on each provide precise spark timing and energy delivery, minimizing misfires and supporting integration. In FSE variants, Toyota's D-4 direct injection technology replaces or supplements MPI, utilizing a high-pressure capable of up to 13 MPa to force fuel through slit-nozzle injectors directly into the , enabling stratified charge operation for improved fuel economy and power output under lean mixtures (air-fuel ratios greater than 20:1), where atomized fuel forms a targeted cloud around the to enhance ignition reliability. Emissions control in the AZ series incorporates an (EGR) valve with a water-cooled aluminum manifold to uniformly distribute cooled exhaust gases back into the , reducing formation by lowering combustion temperatures. A three-way is integrated into the tubular for rapid light-off and efficient conversion of hydrocarbons, , and ; early models also feature to supply fresh air to the exhaust during cold starts, promoting complete oxidation of unburnt fuels. These technologies enable compliance with Euro 4 standards in and ULEV requirements in the United States. The engines use an system with intelligence (ETCS-i), a drive-by-wire setup that adjusts the throttle body electronically for precise airflow management, improved idle stability, and integration with traction control. The AZ engines are designed for unleaded gasoline with an of 87-91 (RON 91-96), balancing performance and knock resistance. In hybrid applications such as the 2AZ-FXE, the further enhances efficiency while leveraging these and emissions systems.

1AZ Series

1AZ-FE

The 1AZ-FE is a 2.0-liter inline-four from Toyota's AZ series, featuring conventional multi-point and serving as the base variant for various mid-size vehicles in both domestic and markets. It displaces 1998 cc with a square bore and stroke of 86 mm × 86 mm, achieving a of 9.8:1. Output varies by application and market tuning, typically delivering 145-152 PS (107-112 kW) at 6000 rpm and 190-193 Nm of at 4000 rpm. This supports responsive performance in compact SUVs and sedans, with the 's aluminum block and head contributing to a lightweight design of approximately 140 kg. Introduced in 2000, the 1AZ-FE remained in production until 2014, gradually replacing the older S-series engines, while the direct-injection 1AZ-FSE was used primarily in and some European models for enhanced efficiency. It was manufactured at Toyota's Kamigo and Shimoyama plants in . Key features include the early adoption of with intelligence (VVT-i) on the intake for optimized low-end and fuel efficiency, paired with the Electronic Throttle Control System with intelligence (ETCS-i) for precise throttle response and integration with traction control systems. The DOHC 16-valve uses a timing for , and the incorporates balance shafts to reduce (NVH), with a 2006 revision enhancing these aspects for even smoother operation. Compared to its S-series predecessor, the 1AZ-FE provides notably smoother operation due to these refinements. The 1AZ-FE powered several models, including the Avensis from 2000 to 2008, RAV4 from 2000 to 2005, Camry ( and ) from 2001 to 2006, Caldina from 2002 to 2007, and Ipsum from 2001 to 2009. These applications highlighted its versatility in front-wheel-drive configurations, often paired with four- or five-speed automatic transmissions. Tuning potential for the 1AZ-FE is limited by its conservative design, but mild modifications such as upgraded camshafts and systems can yield gains of around 10 hp while maintaining reliability. More aggressive upgrades like require significant supporting changes to the fuel and cooling systems.
SpecificationDetails
Displacement1998 cc
Bore × Stroke86 mm × 86 mm
9.8:1
Power Output145-152 PS at 6000 rpm
Torque190-193 Nm at 4000 rpm
ValvetrainDOHC, 16-valve with
Fuel SystemMulti-point injection with ETCS-i

1AZ-FSE

The 1AZ-FSE is a 2.0-liter direct-injection engine in Toyota's AZ series, designed primarily for enhanced in mid-size sedans and wagons. It shares the same aluminum cylinder block and cast-iron liners as the port-injected 1AZ-FE, enabling cost-effective through common components. With a displacement of 1998 cc, bore of 86 mm, and of 86 mm, the engine maintains a square configuration for balanced performance. Its compression ratio is typically 10.5:1 to 11.0:1, optimized for direct injection operation. The 1AZ-FSE delivers 150 PS (110 kW) at 6000 rpm and 200 Nm of torque at 4000 rpm, providing responsive power suitable for everyday driving. Produced from 2003 to 2009, it was mainly deployed in and European markets to meet stricter emission and efficiency standards. Key applications include the from 2003 to 2008, the Allion and Premio models from 2003 to 2007, and the from 2006 to 2007. A standout feature is Toyota's D-4 direct injection system, which uses high-pressure injectors to enable stratified combustion at low loads, improving fuel atomization and reducing emissions. This setup supports air-fuel ratios as lean as 40:1 during cruising, enhancing part-throttle efficiency. Additionally, the engine incorporates the (Acoustic Control Induction System) , which switches between short and long runners to boost mid-range by up to 10% around 3000-4000 rpm. Overall, these technologies yield up to 10% better fuel economy than the 1AZ-FE in highway driving conditions, with combined cycle figures around 8-9 L/100 km depending on the vehicle.

2AZ Series

2AZ-FE

The 2AZ-FE is a 2.4-liter inline-four from Toyota's AZ series, featuring a displacement of 2362 cc achieved through a bore of 88.5 mm and a stroke of 96.0 mm. It employs a of 9.8:1 and delivers power outputs ranging from 158 to 170 PS at 5600-6000 rpm, with between 220 and 230 Nm at 4000 rpm, depending on market-specific tuning and applications. Like other AZ engines, it utilizes an aluminum block and head construction, contributing to improved weight-to-power ratios for enhanced vehicle efficiency. The recommended engine oil viscosity is SAE 5W-20 or SAE 0W-20. Production of the 2AZ-FE spanned from 2000 to 2012, making it the longest-running variant in the AZ family, with manufacturing at facilities in , the , and . A notable 2006 update for U.S. models included revised pistons to refine internal dynamics, while later versions incorporated optional on the exhaust side, boosting power by approximately 5 hp. The engine powered a wide array of and related vehicles, emphasizing sedans, SUVs, and coupes for mainstream markets. Key applications include the (2002-2011), RAV4 (2001-2008), Highlander and Kluger (2001-2007), Matrix and Corolla (2003-2008), (2005-2010), and 250h (2009-2012). Designed for balanced daily driving, the 2AZ-FE offers responsive performance suitable for urban and highway use, with 0-60 mph times of 8-9 seconds in sedan configurations like the Camry.

2AZ-FSE

The 2AZ-FSE is a 2.4-liter direct-injection variant of the AZ engine family, optimized for advanced and performance in luxury-oriented vehicles. It has a displacement of 2362 cc, with the same bore and stroke dimensions as the 2AZ-FE (88.5 mm × 96.0 mm) and a of 11.0:1 to support stratified charge operation. The engine produces 163 PS (120 kW) at 5800 rpm and 230 Nm of at 4000 rpm, balancing responsive with refined driving characteristics. Introduced in 2006 and produced until 2009, the 2AZ-FSE was limited to Asian markets, where it powered select premium sedans including the from 2006 to 2009, the Allion from 2007 to 2010, and the Axio from 2007 to 2012. This engine builds briefly on the direct-injection principles of the smaller 1AZ-FSE, scaling up displacement for higher output while prioritizing smooth power delivery in urban and highway conditions. Key to its design is the D-4 direct injection system, which delivers stratified charge combustion at part load for efficiency and homogeneous mixture at full load for maximum power. Certain applications incorporate variable exhaust (VVT-i on exhaust cams) to broaden the curve and lower emissions. Overall, the stratified charge capability makes it well-suited for efficiency-focused luxury models.

2AZ-FXE

The 2AZ-FXE is a 2.4-liter hybrid-specific variant of Toyota's AZ engine series, designed exclusively for integration with the company's (HSD) system. This inline-four engine employs an to enhance , prioritizing fuel economy and smooth operation over peak power in hybrid applications. Produced from 2005 to 2010, it features a displacement of 2362 cc, with a bore of 88.5 mm and stroke of 96 mm. The geometric is 12.5:1, but the achieves an effective compression ratio of approximately 9.5:1 through late intake valve closing via , resulting in a high effective of 12:1 for improved efficiency. The delivers 147 PS (108 kW) at 6000 rpm and 188 Nm of at 4000 rpm on its own, while the combined system output with the reaches 187 PS, enabling seamless transitions between electric and power. Unique to hybrid applications, it incorporates an electric water pump to reduce parasitic losses and integrates with the MG1 starter-generator for efficient start-stop functionality and support. Optimized for hybrid mode, the 2AZ-FXE significantly higher efficiency due to the and HSD synergy. Introduced in the second-generation Hybrid minivan in 2005 (known as Estima Hybrid in some markets from 2006), the 2AZ-FXE powered select luxury and midsize hybrid models through 2010. Key applications include the Hybrid (AHV40 series, 2007-2010), 250h (2010), and Hybrid (2005-2010). In performance, it emphasizes refinement and economy, supporting pure (EV) mode operation up to 40 km/h for low-speed urban driving, which contributes to overall fuel savings and reduced emissions in real-world use. The VVT-i system allows variable Atkinson operation, adjusting valve timing to balance efficiency and power demands across the hybrid .

3AZ Series

3AZ-FXE

The 3AZ-FXE is a 2.4-liter hybrid-specific variant in the Toyota AZ engine family, developed as an analogue to the 2AZ-FXE for the Chinese market. It features a displacement of 2362 cc, with a bore of 88.5 mm and stroke of 96.0 mm, and operates on an with a geometric of 12.5:1. The engine delivers 150 PS (110 kW) at 6000 rpm and 187 Nm of torque at 4400 rpm, always paired with an in Toyota's system, resulting in a combined system output exceeding 200 PS. Production occurred from 2010 to around 2014. This engine shares the core architecture of the 2AZ-FXE but includes refinements tailored for local manufacturing and market conditions in through the . Key unique features include an improved enabled by variable valve timing-intelligent () on both intake and exhaust cams, which allows for broader efficiency across operating ranges by adjusting valve overlap to reduce pumping losses. It integrates with a higher-voltage nickel-metal hydride (NiMH) rated at 244.8 V, enhancing energy recovery compared to smaller hybrid systems. is optimized via the acting as a generator during deceleration, capturing to recharge the battery, particularly suited for urban cycles common in Chinese cities. The primary application was the Camry Hybrid (AHV40 series), a mid-size sedan focused on fuel economy for family use. In hybrid mode, the 3AZ-FXE emphasizes over raw performance, achieving up to approximately 20 km/L in combined driving for the Camry Hybrid, thanks to seamless transitions between electric assist and gasoline operation. This setup prioritizes low emissions and smooth power delivery for larger sedans, with the Atkinson cycle's late closing reducing effective compression for better at part loads. The engine's aluminum block with cast-iron liners and electronic further supports its role in Toyota's early hybrid expansion in emerging markets.

Reliability and Issues

Excessive Oil Consumption

The excessive oil consumption issue in the Toyota AZ engine family primarily affects the 2AZ-FE variant equipped in U.S.-specification vehicles produced from 2006 to 2011. This problem stems from the low-tension piston rings, which were designed to reduce and contribute to weight savings in the 2AZ-FE for better , but allow engine oil to seep past into the where it burns. As a result, affected engines can consume up to 1 of oil per 1,200 miles. The condition impacts select models, including the 2007–2011 Camry, 2006–2008 RAV4, and 2009–2010 Corolla and Matrix. Unlike the port-injected FE variants, the direct-injection FSE and hybrid FXE versions of the AZ engines do not experience this issue due to their differing piston and ring designs. Symptoms include visible blue smoke from the exhaust, particularly on startup or acceleration, as oil burns in the cylinders, along with fouled spark plugs coated in oil residue. Over time, prolonged oil burning can lead to catalytic converter damage, often after approximately 150,000 km of operation, due to contamination from unburned hydrocarbons. The issue also prompted class-action lawsuits in the U.S., resulting in settlements for affected owners. In response, issued T-SB-0094-11 in 2011, outlining a repair procedure involving the replacement of the and sets to address the consumption. The company also introduced a redesigned assembly starting in 2010 model-year production to prevent the issue in later units. Additionally, Warranty Enhancement Program ZE7 extended coverage for eligible repairs, with primary coverage until October 31, 2016 (regardless of mileage) and secondary coverage for 10 years or 150,000 miles (approximately 240,000 km) from the vehicle's in-service date, provided the engine consumes more than 1 quart per 1,200 miles during a dealer-performed test.

Cylinder Head and Gasket Problems

The Toyota AZ engine family, particularly the 2AZ-FE variant, is prone to thread stripping in the aluminum cylinder block where the bolts secure, especially the rear and middle M10 or M11 bolts. This issue arises due to the relatively weak threads in the block material, which can fail under the specified torque-to-yield procedure of approximately 79 Nm initial torque followed by an additional 90-degree turn, leading to insufficient clamping force and subsequent failure. Symptoms typically emerge after around 100,000 km of operation and include leaking into the , resulting in overheating, white smoke from the exhaust indicating burning , and cylinder misfires due to compression loss. In severe cases, this can cause or further damage if not addressed promptly. The problem predominantly affects early production models equipped with the 2AZ-FE engine, such as the Camry (2002–2006), Highlander (2001–2007), RAV4 (2004–2005), and Solara (2002–2006); isolated cases have been reported in 1AZ-FE-equipped RAV4 (2001–2005). Variants with direct injection, like the 1AZ-FSE and 2AZ-FSE, experience this issue less frequently owing to differences in design and bolt configuration. Repairs involve installing Time-Sert or similar thread inserts into the damaged block holes after removing the short block assembly, followed by replacement of the , bolts, and related components; in extreme cases where multiple threads are compromised, full replacement may be necessary. These procedures, detailed in Toyota T-SB-0015-11, typically cost between $1,500 and $3,000 depending on labor and parts. Toyota addressed the issue through TSBs recommending verification during service, with updated block designs and stronger bolts implemented starting in 2007 production to enhance thread durability and prevent recurrence.

References

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  15. https://www.toyota-global.com/company/history_of_toyota/75years/data/automotive_business/production/production/japan/general_status/shimoyama.html
  16. https://www.engine-specs.net/toyota/2az-fe.html
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  19. https://www.toyotanation.com/threads/timing-chain-maintenance-2az-fe-engine-2002-toyota-camry-4-cyl.1225297/
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  21. https://www.toyotanation.com/threads/2az-fe-2-4-liter-interference-or-non-interference-engine.1762082/
  22. https://www.youtube.com/watch?v=9txGpAxixcg
  23. https://www.ziptekautoparts.com/News/Toyota-1AZ-FE-FSE-2-0L-Engine-Specs-Problems-Reliability.html
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  25. https://alflash.com.ua/d4e.htm
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  30. https://media.toyota.co.uk/new-toyota-rav4-replaces-style-icon/
  31. https://www.torquecars.com/toyota/az-tuning.php
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  33. https://global.toyota/en/detail/7901843
  34. https://assets.sia.toyota.com/publications/en/om-s/OM12E11U/pdf/OM12E11U.pdf
  35. https://static.nhtsa.gov/odi/tsbs/2013/MC-10132131-9999.pdf
  36. https://fastestlaps.com/models/toyota-camry-2-4
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  38. https://forums.genvibe.com/phpBB3/viewtopic.php?t=47886
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  40. https://global.toyota/en/newsroom/toyota/22749246.html
  41. https://www.toyota-global.com/company/history_of_toyota/75years/vehicle_lineage/car/id60000632/index.html
  42. https://automobile.fandom.com/wiki/Toyota_Camry_Hybrid
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  44. https://www.torquenews.com/17992/my-son-laws-2007-toyota-camry-blowing-blue-smoke-exhaust-and-i-told-him-get-it-scheduled-oil
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  46. https://reliantautorepair.com/toyota-engine-oil-burning-problem-what-you-need-to-know/
  47. https://static.nhtsa.gov/odi/tsbs/2015/MC-10134468-9999.pdf
  48. https://stevesautomotivespecialists.com/toyota-engine-oil-consumption/
  49. https://bobistheoilguy.com/forums/threads/minimizing-danger-to-the-catalytic-converter-in-an-oil-burner.361412/
  50. https://ethenostrofflaw.com/toyota-oil-burning-lawsuit/
  51. https://static.nhtsa.gov/odi/tsbs/2015/MC-10111568-9999.pdf
  52. http://media.fixed-ops.com/Toy_ServiceBulletins/sb0015t11.pdf
  53. https://www.toyota-club.net/files/faq/04-11-20_faq_az_eng.htm
  54. https://www.tsbsearch.com/Toyota/T-SB-0015-11
  55. https://www.rav4world.com/threads/stripped-head-bolt-story-long-term-fix-and-reliability.186882/
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