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.
BOSCH AFC/MPC Fuel Injection Systems: Description
The Bosch Air Flow Controlled (AFC) and Manifold Pressure Controlled (MPC) fuel injection systems that are very similar in construction and components. The main difference is that the AFC system uses an air sensor flap with a pickup and a relay set to control the amount of fuel injected into the engine. See Figure and Figure.
The MPC system uses manifold pressure and triggering contacts, in the distributor, to control the amount of fuel injected into the engine. Both systems measure the volume of air going into the engine. The MPC system does this by measuring pressure changes in the manifold while the AFC system measures air flow through the intake manifold.
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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.