Porsche M-28-49 Engine (1985–1988) – Specs, Problems & Compatibility Database

The Porsche M28.49 is a 2,479 cc, inline‑four petrol engine produced between 1985 and 1988. It powered the front — engine Porsche 944 and featured a water — cooled architecture with an aluminum block, cast — iron cylinder liners, and dual balance shafts for smoothness. Equipped with Bosch LH — Jetronic electronic fuel injection and a SOHC 8 — valve head, it delivered 125 kW (170 PS) and 222 Nm of torque.

Fitted exclusively to the 944 (including 944 S base variants in some markets…

Porsche Engine
Compliance Note:

Production years 1985–1988 meet national emissions standards of the era; Euro 1-equivalent compliance applies to select export models .

Porsche M-28-49 Technical Specifications

The Porsche M28.49 is a 2,479 cc inline‑four petrol engine engineered for front-engine sports coupes (1985–1988). It combines Bosch LH-Jetronic electronic fuel injection with dual balance shafts and SOHC valvetrain to deliver smooth, refined power with strong low-end torque. Designed before formal EU emissions standards, later units incorporated modifications to meet national and VCA-equivalent requirements.

ParameterValueSource
Displacement
2,479 cc
Fuel type
Petrol (RON 95 min)
Configuration
Inline‑4, SOHC, 8‑valve
Aspiration
Naturally aspirated
Bore × stroke
100.0 mm × 79.0 mm
Power output
125 kW (170 PS) @ 5,800 rpm
Torque
222 Nm @ 4,200 rpm
Fuel system
Bosch LH-Jetronic electronic injection
Emissions standard
Pre-Euro; national equivalents (e.g., VCA)
Compression ratio
9.7:1
Cooling system
Water-cooled
Turbocharger
None
Timing system
Chain-driven SOHC with dual balance shafts
Oil type
Refer to vehicle handbook / manufacturer specification
Dry weight
142 kg

Porsche M-28-49 Compatible Models

The Porsche M28.49 was used exclusively in Porsche's 944 platform with front-mounted, longitudinal orientation and no external licensing. This engine received minor updates—revised balance shaft bearings from mid-1987 and updated ECU calibrations for catalytic models—and all adaptations are documented in OEM technical bulletins.

Make:
Porsche
Years:
1985–1988
Models:
944
Variants:
944, 944 S (base variants in select markets)
View Source
Porsche ETK Doc. E944-102

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Common Reliability Issues - PORSCHE M-28-49 Compatible Models

Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.

Balance shaft bearing failure
Symptoms: Low oil pressure (especially at idle when hot), metallic knocking from engine front, oil pump cavitation noise.
Cause: Needle bearing fatigue in balance shaft assembly due to marginal oil supply and extended service intervals.
Fix: Replace balance shaft assembly with updated OEM bearings per TSB-944-1987; inspect oil pump and crankshaft journals for collateral damage.
Timing chain tensioner wear
Symptoms: Rattling on cold start, rough idle, ignition timing drift.
Cause: Tensioner spring weakening over time; exacerbated by infrequent oil changes.
Fix: Install new OEM timing chain, tensioner, and guides; verify cam timing alignment after replacement.
LH-Jetronic sensor or ground faults
Symptoms: Hard starts, erratic idle, poor fuel economy, failed emissions test.
Cause: Aging oxygen sensor, corroded grounds, or degraded air flow meter wiring.
Fix: Replace sensors with OEM-spec components; clean engine and ECU grounds per TIS FT-944-86.
Water pump and thermostat failure
Symptoms: Overheating, coolant leaks near front pulley, inconsistent cabin heat.
Cause: Plastic impeller degradation or thermostat sticking due to scale buildup from old coolant.
Fix: Replace water pump and thermostat with OEM parts; flush cooling system and refill with correct 50/50 ethylene glycol coolant.
Research Basis

Analysis derived from manufacturer technical service bulletins and industry workshop records. Repair procedures should follow manufacturer guidelines.

PORSCHE M-28-49 FAQ Common Questions Answered

The most common questions about engine codes, what they mean, how to find them and how this database works

The M28.49 can be dependable if maintained properly, but early models (1985–mid-1987) are prone to balance shaft bearing failure. Post-mid-1987 units with updated bearings are significantly more robust. Critical factors include strict oil change intervals, using correct coolant, and monitoring oil pressure. Neglect often leads to catastrophic lubrication failure.

Top issues include balance shaft bearing wear, timing chain tensioner degradation, LH-Jetronic sensor faults, and water pump leaks. These are well-documented in Porsche service bulletins TSB-944-1987 and related TIS updates. Oil and cooling system neglect are primary accelerants.

Exclusively the Porsche 944 from 1985 to 1988, including standard and select base S variants in specific markets. It was never used in 924, 944 Turbo, 968, or other Porsche lines. All are front-engine, water-cooled layouts.

Aftermarket ECU tuning is common on the M-28-49 platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.

Typical consumption is 10–12 L/100km (24–19 mpg UK) in mixed driving. Highway cruising can reach 8.5 L/100km (33 mpg UK). The engine prioritizes smoothness and torque over peak efficiency, though it remains reasonable for a 1980s sports coupe.

No. The M28.49 is a non-interference engine. If the timing chain fails, valves and pistons do not collide, reducing catastrophic risk. However, balance shaft and oil pump integrity should still be monitored.

Porsche specifies SAE 10W-40 mineral oil meeting API SF/CC standards. Synthetic oils were not approved for this engine. Change every 7,500 km or annually to protect the balance shaft bearings and hydraulic lifters.

Research Resources

Comprehensive technical documentation and regulatory references

Platform Overview

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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.

Regulatory Context

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

Type-approval guidance and documentation.

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