Intake Air System: Diagnosis Honda Pilot I

Throttle Body Test

Note. Do not adjust the throttle stop screw. It is preset at the factory. If the malfunction indicator lamp (MIL) has been reported on, check for diagnostic trouble codes (DTCs) (see HOW TO USE THE HONDA DIAGNOSTIC SYSTEM (HDS) ).

1. With the engine off, check the throttle cable operation. The cable should move without binding or sticking. If the cable moves OK, go to step 2. If the cable binds or sticks, check it and its routing. If it's faulty, reroute it or replace it (see «Throttle Cable Removal/Installation»(ref-173999-S23768700522005041500000) ) and adjust it (see «Throttle Cable Adjustment»(ref-173999-S34536006702005041500000) ), then go to step 2.
2. Move the throttle lever by hand to see if the throttle valve and/or shaft are too loose or too tight. If there is excessive play in the throttle valve shaft, or any binding in the throttle valve at the fully closed position, replace the throttle body (see «Throttle Body Removal/Installation»(ref-173999-S06016012062005041500000) ). If the throttle valve and shaft are OK, go to step 3.
3. Connect the scan tool or the HDS to the DLC.
4. Turn the ignition switch ON (II).
5. Check the throttle position with the scan tool or the HDS. There should be about 10% when the throttle is fully closed and about 90% when the throttle is fully opened. If the throttle position is correct, check the throttle body for carbon, sludges, etc. Do the throttle body cleaning if necessary (see «Throttle Body Cleaning»(ref-173999-S27391963092005041500000) ). If the throttle position is not correct, replace the throttle body (see «Throttle Body Removal/Installation»(ref-173999-S06016012062005041500000) ).

Intake Air Bypass Control Thermal Valve Test

Special Tools Required: Vacuum Pump/Gauge, 0-30 in. Hg A973X-041-XXXXX

Scheme 204

1. Start the engine, and let it idle. NOTE: The engine coolant temperature must be below 104°F (40°C).
2. Remove the vacuum hose (A) from the intake duct and connect a vacuum gauge to the hose.
3. Raise and lower the engine speed, and make sure the vacuum gauge reading changes as the rpm changes. If the vacuum reading changes, go to step 4. If the vacuum reading does not change, check for these problems: Misrouted, leaking, broken, or clogged intake air bypass system vacuum lines. A cracked or defective intake air bypass control thermal valve.
4. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on, then let it idle.
5. Raise and lower the engine speed, and make sure the vacuum gauge reading does not change as the rpm changes. If the vacuum reading does not change, the intake air bypass control thermal valve is OK. If the vacuum reading changes, check for these problems: Misrouted, leaking, broken, or clogged intake air bypass system vacuum lines. A cracked or defective intake air bypass control thermal valve.

Scheme 205

1. Remove the cable clamp (A), and the bolts (B).
2. Remove the air cleaner (C).
3. Install the parts in the reverse order of removal.

Scheme 206

1. Remove the cable clamp (A).
2. Remove the air cleaner housing screws (B) and the cover (C).
3. Remove the air cleaner element (D) from the air cleaner housing (E).
4. Install the parts in the reverse order of removal.

Scheme 207

Scheme 208

1. Remove the intake manifold cover (see «INTAKE MANIFOLD REMOVAL & INSTALLATION»(ref-173990-S36628467322005041500000) ).
2. Hold the throttle link (A) to the throttle lever (B). There should be no clearance.
3. Check cable free play at the throttle linkage. Cable deflection (A) should be 10-12 mm (3/8-1/2 in.).
4. If deflection is not within specs (10-12 mm, 3/8-1/2 in.), loosen the locknut (B), turn the adjusting nut (C) until the deflection is as specified, then retighten the locknut.
5. With the cable properly adjusted, check the throttle valve to be sure it opens fully when you push the accelerator pedal to the floor. Also check the throttle valve to be sure it returns to the idle position whenever you release the accelerator pedal.
6. Install the intake manifold cover (see «INTAKE MANIFOLD REMOVAL & INSTALLATION»(ref-173990-S36628467322005041500000) ).

Scheme 209

Scheme 210

Scheme 211

1. Remove the intake manifold cover (see «INTAKE MANIFOLD REMOVAL & INSTALLATION»(ref-173990-S36628467322005041500000) ).
2. Fully open the throttle valve, then remove the throttle cable (A) from the throttle link (B).
3. Loosen the locknut (C), and remove the cable adjuster (D) from the cable bracket (E).
4. Remove the throttle cable (A) from the accelerator pedal (B).
5. Pull off the throttle cable from the vehicle.
6. Install in the reverse order of removal.
7. Remove any slack from the cable while holding the cable adjuster.
8. Turn the adjusting nut (A) until it is 3 mm (1/8 in.) away from the cable bracket (B).
9. Tighten the locknut (C). The cable deflection should be 10-12 mm (3/8-1/2 in.). If deflection is not within spec, readjust the nuts.
10. After the cable is adjusted properly, check the throttle valve to see whether it is able to fully open and close smoothly.
11. Install the intake manifold cover (see «INTAKE MANIFOLD REMOVAL & INSTALLATION»(ref-173990-S36628467322005041500000) ).