The Fiat 159 A4.046 – Petrol is a 1,995 cc, inline-four, naturally aspirated engine produced between 1990 and 1996. It features a cast-iron block, aluminium head, and single-barrel carburettor (Weber 34 IAD), delivering 76 kW (103 PS) at 5,400 rpm and 152 Nm of torque at 2,800 rpm. Its SOHC (single overhead camshaft), 8-valve configuration provides mechanical simplicity and ease of servicing, making it ideal for mid-size sedans and station wagons.
Fitted to the Fiat Tempra 2.0 i.e. and Lancia Dedra 2.0 models, the 159 A4.046 – Petrol was engineered for smooth, refined performance and strong mid-range driveability. It offered a balance of linear power delivery and durability, suitable for long-distance driving. Emissions compliance was achieved through an air injection system and catalytic converter on post-1992 models, meeting Euro 1 standards in select European markets.
One documented concern is premature camshaft lobe wear, highlighted in Fiat Service Information Bulletin 91-06-07. This issue stems from inadequate lubrication in the upper valvetrain, particularly under sustained high-RPM operation or infrequent oil changes. Later production revisions included updated oil gallery drilling and revised camshaft metallurgy to enhance durability.
Production years 1990–1991 meet pre-Euro emissions standards; 1992–1996 models comply with Euro 1 standards (EU Directive 88/77/EEC, Annex I) depending on market.
The Fiat 159 A4.046 – Petrol is a 1,995 cc inline-four naturally aspirated engine developed for Fiat's mid-size vehicle segment (1990–1996). It combines a durable cast-iron block with an aluminium cylinder head and single-barrel carburettor to deliver smooth, linear performance. Designed to meet early European emissions requirements, it balances mechanical robustness with drivability for high-mileage applications.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,995 cc | |
| Fuel type | Petrol (Unleaded RON 95) | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 86.0 mm × 86.0 mm | |
| Power output | 76 kW (103 PS) @ 5,400 rpm | |
| Torque | 152 Nm @ 2,800 rpm | |
| Fuel system | Weber 34 IAD single-barrel carburettor | |
| Emissions standard | Pre-Euro (1990–1991); Euro 1 (1992–1996) | |
| Compression ratio | 9.2:1 | |
| Cooling system | Water-cooled, thermostat-regulated | |
| Turbocharger | Not applicable | |
| Timing system | Rubber-toothed belt (single cam) | |
| Oil type | SAE 10W-40 (API SF/CC) | |
| Dry weight | 156 kg |
The naturally aspirated SOHC design provides smooth, linear power delivery ideal for relaxed cruising but requires regular carburettor tuning to maintain efficiency. SAE 10W-40 mineral oil is recommended with changes every 10,000 km to protect the belt-driven camshaft and valvetrain. The engine is sensitive to timing belt failure due to interference design; replacement every 60,000 km or 4 years is critical. Use of unleaded fuel requires hardened valve seats, retrofitted in 1992 models per Fiat SIB 92-08-05. Pre-1992 units lack catalytic converters; post-1991 models require lead-free fuel and periodic catalyst inspection to prevent blockage.
Oil Specs: Requires SAE 10W-40 API SF/CC specification (Fiat Owner's Manual 159-OM1). Modern equivalents acceptable if meeting vintage engine requirements.
Emissions: Euro 1 applies to 1992–1996 models only (EU Directive 88/77/EEC). Pre-1992 units meet national pre-regulatory standards.
Power Ratings: Measured under UN ECE Regulation 85. Output assumes clean air filter, correct ignition timing, and fresh fuel system (Fiat TIS M159P03).
Fiat Technical Information System (TIS): Docs M159P01, M159P02, SIB 91-06-07
European Commission: Directive 88/77/EEC - Emissions for Light-Duty Vehicles
UN ECE Regulation 85: Power Measurement for Compression Ignition Engines
Fiat ETK Parts Catalogue Vol. 3: Engine Components
The Fiat 159 A4.046 – Petrol was used across Fiat's Tempra platform with transverse mounting and shared with Lancia in executive applications. This engine received platform-specific adaptations—tuned exhaust manifolds in the Tempra and revised cooling fans in hot-climate variants—and from 1992, the introduction of catalytic converters on export models created emissions-related interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the right-side of the cylinder block, near the transmission bellhousing (Fiat TIS M159P01). The 8th VIN digit indicates engine type ('K' for 159 series petrol). Pre-1992 models have chrome valve covers with open air cleaners; post-1992 units feature black-painted covers with emissions vacuum lines. Critical differentiation from diesel variants: 159 A4.046 petrol has a carburettor and distributor, while diesel versions use injection pumps. Service parts require model-year verification—cylinder heads for pre-1992 models lack hardened valve seats and are incompatible with unleaded fuel systems (Fiat SIB 92-08-05).
The 159 A4.046 – Petrol's primary reliability risk is camshaft lobe wear, with elevated incidence in vehicles subjected to sustained high-RPM operation or extended oil intervals. Internal Fiat quality reports from 1993 noted a significant number of pre-1992 engines requiring camshaft replacement before 100,000 km, while Italian Ministry of Transport data links a notable share of valvetrain failures to lubrication neglect. Extended high-load operation and poor oil maintenance increase valvetrain stress, making oil quality and interval adherence critical.
Analysis derived from Fiat technical bulletins (1990-1996) and Italian Ministry of Transport vehicle failure statistics (1991-1997). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about FIAT 159-A4-046.
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