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 - BOSCH Cis: Description
Bosch Continuous Injection System (CIS) is a mechanical fuel injection system which uses airflow sensor assembly connected to fuel distributor to control injection quantity.
Lambda is a feedback control system capable of continuously measuring and correcting air/fuel ratios. Combination of 2 systems allows for both economy and performance with minimal exhaust emissions. See Fig 1 .
System consists of mixture control unit (airflow sensor and fuel distributor), control pressure (warm-up) regulator, auxiliary air regulator, cold start valve, thermo time switch, fuel injectors, fuel pump, filter, oxygen (O2) sensor, electronic control unit (ECU), frequency valve and catalytic converter.
Some models use additional components, such as thermo vacuum valve, hot start pulse relay or constant idle speed control system.
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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.
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