Fuel Cut Control Inspection - Mazda 3 Workshop Manual

Mazda 3 Workshop Manual – Engine + Wiring Diagrams + Diagnostic Trouble Codes

Fuel Cut Control Inspection

1. Connect the WDS or equivalent to the DLC-2.
2. Warm up the engine and idle it.
3. Turn off all the electrical loads and the A/C switch.
4. Using "RPM" of the PID/data monitor function, verify the engine speed.
5. Using a soundscope or a screwdriver, verify the operation sound of the fuel injector at all cylinders.
(1) Open the throttle valve and increase the engine speed to 4,000 rpm.
(2) Close the throttle valve instantaneously and verify that the fuel injector operation sound stops
until the engine speed decreases to approx. 1,200 rpm and the sound is heard when the engine
speed is approx. 1,200 rpm or less.
• If the sound does not stop at all cylinders, inspect the following:
- PCM input signal circuit (sensor, wiring harness)
• Throttle opening signal (TP sensor)
• If the sound does not stop at specific cylinders, inspect the following:
- Corresponding fuel injector and related wiring harnesses and connectors
• If the operation sound stops at all cylinders but the engine speed at which the operation sound
recovers is not within the specification, inspect the following:
- PCM input signal circuit (sensor, wiring harness)
• Load/no load detection signal (neutral/CPP switch (MTX), TR switch (ATX))
• Water temperature signal (ECT sensor)
6. Place the vehicle on a chassis dynamometer.
7. Inspect the following using the WDS or equivalent.
(1) Verify the injector actuation time using the PID/data monitor function.
(2) Depress the accelerator pedal and increase the engine speed to 4,000 rpm. (Loaded range)
(3) With the accelerator pedal released (without depressing the brake pedal), verify that the
injector actuation time of 0 ms is indicated until the engine speed decreases to approx. 1,200
rpm, and then the actuation time 2-5 ms is indicated when the engine speed decreases
to approx. 1,000 rpm or less.
Downloaded from https://carmanualshub.com/ - automotive repair manuals website