Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1987 Porsche 928 AutomaticFACTORY OEM SERVICE PROCEDURE
Fuel Injection System - BOSCH LH
- Description
- Notes
- Fuel Circuit
- Airflow
- Control Unit
- Hot Wire Sensor
- NTC Temperature Sensor II
- Throttle Switch (Fuel System)
- Idle Speed Contact Functions
- Full Throttle Contact Functions
- Idle Speed Stabilization
- Air Regulating Valve
- Testing Plug
- Fuel Injectors
- Tank Venting System
- EZF Ignition System
- LH & EZF Electrical System
- EZF Control Unit
- Speed/Reference Mark Sensor
- Temperature Sensor I (Intake Air)
- Temperature Sensor II (Engine)
- Throttle Switch (Ignition System)
- Ignition Distributors
- TDC Transmitter
- Adjustments
- Testing
- Preparation For Testing
- Test Equipment
- Test 1 - Checking Ground & Plug Connections
- Test 2 - EZF Control Unit Power Supply
- Test 3 - Speed/Reference Mark Sensor
- Test 4 - Checking Load Sensor
- Test 5 - Temperature Sensor I
- Test 6 - Temp. Sensor II/EZF Side Of Engine Temp. Sensor
- Test 7 - Throttle Switch (Idle Contact)
- Test 8 - Throttle Switch Full Load
- Test 9 - Ignition System
- Test 10 - Octane Loop
- Test 11 - Power Supply For LH Control Unit & Fuel Pump
- Test 12 - LH Hot Wire Air Mass Sensor
- Test 13 - LH Temperature Sensor II
- Test 14 - Throttle Switch (Idle)
- Test 15 - Throttle Switch (Full Load)
- Test 16 - Fuel Injectors
- Test 17 - Air Regulating Valve
- Test 18 - Co & Idle Speed Adjustment
- Test 19 - Leaks In Intake System
- Test 20 - Fuel Pressure
- Test 21 - Oxygen Sensor & LH Fuel Control Unit
- Removal & Installation
- Wiring Diagram
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.