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.
Differential Pressure Regulator
The differential pressure regulator controls the fuel flow in the lower chamber of the fuel distributor. This helps to determine the fuel mixture.The regulator designates zero Milliamps (mA) as the reference point. The unit operates with current from the FICU that ranges between +10 mA (rich) to -10 mA (lean).
When the starter is operated, current to the differential pressure regulator is increased to enrich the fuel mixture. This will take place whenever the engine is started and the amount of increase will be regulated by coolant temperature. In extreme cold, current can be as high as 140 mA.
During cold acceleration, current can briefly raise to 6Ma to enrich fuel mixture. The enrichment is determined by engine speed and signals from the temperature sensor and temperature sensor.
During full load operation, the full throttle switch closes, sending a signal to the ICU. The ICU sends a signal approximately 3 mA greater than the signal that is currently present. This signal will vary, depending on engine speed and altitude.
When vehicle is decelerated, fuel to injectors is shut off by reversing current to -50 mA to -60 mA. The engine speed at which this reversing will take place is regulated by coolant temperature. Current will also be reversed if engine speed reaches 6600 RPM, acting as a governor. The differential pressure regulator is attached to the fuel distributor.
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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.