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.
Fuel Injection System - LH (16-Valve): Description
The Bosch LH-Jetronic fuel injection system integrates the fuel injection and idle speed control functions into one system. One electronic control unit (ECU) controls all system functions.
The LH Jetronic fuel injection system operates with moderate fuel pressure, held constant by a line pressure regulator. Fuel is metered into the cylinders by electrically controlled solenoid valves in the injectors. The injectors are installed just ahead of each cylinder intake valve.
Actual duration of injection (2-12 milliseconds), is determined by the ECU. The ECU receives several signals on various driving, engine and outside conditions from a set of sensors and an air mass meter. See Fig 1 .
Signals from air mass meter and exhaust gas oxygen sensor provide most of the information used by the electronic control unit to maintain proper air/fuel ratios. An idle speed adjustment screw is located on throttle housing.
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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.