Engine - Intake-Air System: Diagnosis Mazda RX-8 I

INTAKE-AIR SYSTEM INSPECTION

1. Perform the following intake-air system part inspections. NOTE: If there is improper installation or a malfunction of an intake-air system part, it could cause poor emission, low engine output, or rough idling.

Scheme 9

1. Visually inspect the following items: If there is any abnormality, reinstall or replace the air hose. Is there any looseness or disconnection of air hose and air cleaner cover connecting parts? Is there any looseness or disconnection of air hose and throttle body connecting parts? Is the hose correctly installed? Are there any cracks or splits in the air hose?

Hose Inspection

1. Refer to the intake-air system hose routing diagram and verify that the hoses are installed in the correct positions. (See «INTAKE-AIR SYSTEM HOSE ROUTING DIAGRAM»(ref-178322-S04889313712005061400000) .) If there is any abnormality, install in the correct position.
2. Verify that there is no crushing, cracks, or splits on the intake air hose. If there is any abnormality, repair or replace the intake air hose.

Scheme 10

1. Remove the fresh air duct. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .)
2. Verify that there is no damage or peeling on the heat shield gasket for the fresh air duct. If there is any abnormality, repair or replace the fresh air duct.

Scheme 11

1. Verify that the air cleaner insulator has been installed. If it has not been installed, install an air cleaner insulator.

AIR CLEANER ELEMENT INSPECTION

1. Remove the air hose. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .)
2. Unclip the air cleaner cover. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .)
3. Remove the air cleaner element. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .)
4. Inspect the following items: If there is any abnormality, clean or replace the air cleaner element. Has the replacement interval come? Is the air cleaner element soiled, damaged, or bent? Are the air cleaner case and the air cleaner element correctly sealed? Is the correct air cleaner element installed?

THROTTLE BODY INSPECTION

Note. Perform the following inspection only when directed.

Scheme 12

Scheme 13

Scheme 14

1. Remove the throttle body. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .)
2. Verify that there is no continuity between the throttle body and throttle body each terminal using an ohmmeter. If not as specified, replace the throttle body. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .)
3. Measure the resistance between the throttle actuator terminals using an ohmmeter. If not as specified, replace the throttle body. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .) If as specified, carry out the «CIRCUIT OPEN/SHORT INSPECTION»(ref-178322-S06989304582005061400000) . Throttle actuator resistance

Scheme 15

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for open or short (continuity check).

Throttle Valve Inspection

1. Remove the throttle body. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION»(ref-178322-S25288823672005061400000) .)
2. Open the throttle valve from the closed position to open fully by hand.
3. Verify that the throttle valve moves smoothly. If cannot be verified, replace the throttle body.
4. Release hand from the throttle valve when at the fully open position.
5. Verify that the throttle valve returns to the closed position smoothly by spring force. If cannot be verified, replace the throttle body.
6. Press the throttle valve from the closed position to the fully closed position by hand.
7. Verify that the throttle valve move approx. 5°. If cannot be verified, replace the throttle body.

Circuit Open/Short Inspection

1. Disconnect the PCM connector.
2. Inspect the following wiring harness for open or short.