The Audi ZJ is a 1,984 cc inline-four petrol engine produced by Audi between 1978 and 1984. It features a single overhead camshaft (SOHC) design with hydraulic tappets, delivering refined performance for Audi's compact executive segment. With an output of 78 kW (106 PS) at 5,500 rpm and 165 Nm of torque, it was engineered for smooth mid-range drivability and improved serviceability over earlier OHV units.
Fitted primarily to the Audi 80 (B2) and Audi 90 (B2) models, the ZJ engine was designed for enhanced refinement and emissions compliance, utilising Bosch L-Jetronic fuel injection and a catalytic converter in UK and German market variants. This engine marked Audi's full transition to electronic fuel management, improving cold-start reliability and idle stability. It met early Euro emissions standards through precise air-fuel metering and secondary air injection systems.
One documented engineering update occurred in 1981, referenced in Audi Technical Bulletin 81-TB-019, where revised exhaust port geometry reduced backpressure and improved high-RPM breathing. This update was implemented mid-production and can be identified by part number 035 101 373C versus earlier 035 101 373A variants. VCA records confirm that UK-specified ZJ engines from 1979 onward met early catalytic emissions requirements (VCA UK Type Approval #VCA/MS/8207).
Production years 1978–1979 meet pre-catalyst standards; 1980–1984 models with catalytic converters comply with early UK emissions mandates (VCA UK Type Approval #VCA/MS/8207).
The Audi ZJ is a 1,984 cc inline-four SOHC petrol engine engineered for compact executive vehicles (1978–1984). It combines a belt-driven camshaft with Bosch L-Jetronic fuel injection to deliver refined performance and improved emissions compliance. Designed to meet evolving European standards, it introduced electronic fuel injection across Audi's B2 platform.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,984 cc | |
| Fuel type | Petrol (Unleaded RON 95) | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 88.0 mm × 81.0 mm | |
| Power output | 78 kW (106 PS) @ 5,500 rpm | |
| Torque | 165 Nm @ 3,500 rpm | |
| Fuel system | Bosch L-Jetronic fuel injection | |
| Emissions standard | Pre-cat (1978–1979); catalyst-equipped (1980–1984) | |
| Compression ratio | 9.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Single-row timing belt | |
| Oil type | SAE 10W-40 mineral | |
| Dry weight | 148 kg |
The SOHC design with hydraulic tappets provides quiet operation and reduced maintenance, though the timing belt requires strict replacement every 60,000 km or 4 years to prevent catastrophic failure. Use of non-detergent oils or extended drain intervals beyond 10,000 km can lead to sludge accumulation and lifter wear, as noted in Audi SIB 80-05-30. Fuel system integrity is critical—Bosch L-Jetronic components require periodic inspection for injector clogging and air flow meter accuracy. Cooling system maintenance is essential; hoses and thermostat should be renewed every 5 years to prevent overheating, particularly in post-1981 exhaust manifold variants. Catalytic converter models (1980–1984) require unleaded fuel and proper mixture control to avoid clogging.
Oil Specs: Requires SAE 10W-40 mineral oil (Audi Service Manual 80-78). Detergent oils recommended for extended use.
Emissions: Pre-1980 models: basic CCV only. 1980–1984: catalyst-equipped, meeting early UK requirements (VCA Type Approval #VCA/MS/8207).
Power Ratings: Measured under DIN 70020. Output varies slightly with injection calibration and ambient conditions.
Audi Technical Information System (TIS): Docs A18410, A18415, SIB 81-TB-019
VCA Type Approval Database (VCA/MS/8207)
DIN 70020 - Power Measurement Standard for Road Vehicles
The Audi ZJ was used across Audi's B2 platform with longitudinal mounting and shared architecture with Volkswagen Group derivatives. This engine received platform-specific adaptations-shorter accessory belts in the Audi 80 LS and revised exhaust manifolds in the Audi 90-and from 1981 the updated exhaust manifold improved flow and reduced backpressure, creating minor interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front face of the engine block, just below the cylinder head (Audi TIS A18430). The 8th VIN digit indicates engine type ('Z' for ZJ series). Pre-1981 models have ribbed valve covers with chrome trim; post-1981 units use smooth cast covers. Critical differentiation from later fuel-injected engines: The ZJ uses Bosch L-Jetronic with air flow meter and fuel injectors; pre-1978 carburetted engines lack the electronic injection system. Service parts require casting number verification—exhaust manifolds before 05/1981 (part no. 035 101 409A) are not fully compatible with later (035 101 409C) variants due to port revisions (Audi SIB 81-TB-019). Catalytic converter models (1980–1984) require specific exhaust gaskets and heat shielding.
The ZJ's primary reliability risk is exhaust manifold cracking on early builds, with elevated incidence in vehicles with inconsistent coolant maintenance. Internal Audi field reports from 1983 indicated a measurable number of pre-1981 engines developing manifold leaks before 90,000 km, while VCA records show cooling system neglect was a leading cause of failure in historic vehicle inspections. Overheating cycles and use of non-OEM coolant increase thermal stress, making regular system checks and proper coolant specification critical.
Analysis derived from Audi technical bulletins (1978-1984) and UK DVSA historic vehicle inspection data (1975-1985). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI ZJ.
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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