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.
Deceleration System: Operation
When engine is at normal operating temperature and throttle is suddenly closed, deceleration fuel cut-off begins when the engine speed reaches 1800 RPM. Deceleration is detected by a microswitch and deceleration relay. When engine is above 1800 RPM, deceleration relay allows positive current to the deceleration valve. This causes throttle flap to move against idle stop which closes microswitch. This energizes 2-speed relay which grounds cold cut-out relay and opens thermocontact. The deceleration valve opens and equalizes pressure on air flow sensor. Injection is resumed when engine reaches 1200 RPM or is accelerated.
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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.