Engine Controls - On-Vehicle Adjustments Acura MDX I

ENGINE MECHANICAL

Before performing any on-vehicle adjustments to fuel or ignition system, ensure engine mechanical condition is okay.

VALVE CLEARANCE

Note. 3.5RL is equipped with hydraulic lifters. Adjustment is not required.

MDX, 3.2CL & 3.2TL

1. Ensure cylinder head temperature is less than 100°F (38°C). On 3.2CL and 3.2TL, remove strut brace. On all models, remove ignition coil cover and intake manifold cover. On 3.2CL and 3.2TL Type S models, remove water bypass hoses. Disconnect Traction Control System (TCS) control valve actuator and TCS control valve angle sensor connector from TCS control valve assembly. Remove bolt securing TCS control valve bracket. On all models, remove Evaporative Emission (EVAP) control canister hose, breather tube, vacuum hose and intake air duct. Loosen lock nuts and remove throttle and cruise control cables.
2. Remove brake booster vacuum hose, vacuum hoses, and PCV hose. Remove breather pipe and water bypass hose. Remove power steering hose clamp. Disconnect intake manifold runner control (IMRC) actuator connector. Remove IMRC actuator. Remove 2 bolts from wire harness holder. Remove Intake Air Temperature (IAT), Idle Air Control (IAC), Throttle Position Sensor (TPS) and Manifold Absolute Pressure (MAP) sensor connectors. On MDX, also disconnect EVAP canister purge valve connector. On all models, remove wire harness clamps and holders. Move wire harness out of way. Remove ignition coils if necessary. Remove upper intake cover and intake manifold. Remove cylinder head covers.
3. Rotate crankshaft clockwise until cylinder No. 1 is at TDC. Cylinder No. 1 TDC mark on camshaft sprocket should be aligned with pointer on timing belt cover. Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 1. See «VALVE CLEARANCE ADJUSTMENT»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments) table. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary.
4. Rotate crankshaft clockwise until cylinder No. 4 is at TDC. Cylinder No. 4 TDC mark on camshaft sprocket should be aligned with pointer on timing belt cover. Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 4. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary.
5. Rotate crankshaft clockwise until cylinder No. 2 is at TDC. Cylinder No. 2 TDC mark on camshaft sprocket should be aligned with pointer on timing belt cover. Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 2. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary.
6. Rotate crankshaft clockwise until cylinder No. 5 is at TDC. Cylinder No. 5 TDC mark on camshaft sprocket should be aligned with pointer on timing belt cover. Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 5. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary.
7. Rotate crankshaft clockwise until cylinder No. 3 is at TDC. Cylinder No. 3 TDC mark on camshaft sprocket should be aligned with pointer on timing belt cover. Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 3. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary.
8. Rotate crankshaft clockwise until cylinder No. 6 is at TDC. Cylinder No. 6 TDC mark on camshaft sprocket should be aligned with TDC pointer on timing belt cover. Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 6. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary. After adjusting valves, reinstall removed components and ensure crankshaft pulley bolt is tightened to 181 ft. lbs. (245 N.m).

VALVE CLEARANCE ADJUSTMENT

Scheme 1

1. Ensure cylinder head temperature is less than 100°F (38°C). Remove cylinder head cover.
2. Rotate crankshaft clockwise until cylinder No. 1 is at TDC. Align TDC marks on Variable Valve Timing Control (VTC) actuator and exhaust camshaft sprocket. (Scheme 1) Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 1. See «VALVE CLEARANCE ADJUSTMENT»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments) table. Tighten valve adjusting screw lock nut to 10 ft. lbs. (14 N.m) and recheck valve clearance. Repeat adjustment if necessary.
3. Rotate crankshaft clockwise 180 degrees (camshaft sprockets will rotate 90 degrees). Adjust valves on cylinder No. 3. Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 3. Tighten valve adjusting screw lock nut to 10 ft. lbs. (14 N.m) and recheck valve clearance. Repeat adjustment if necessary.
4. Rotate crankshaft clockwise 180 degrees (camshaft sprockets will rotate 90 degrees). Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 4. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary.
5. Rotate crankshaft clockwise 180 degrees (camshaft sprockets will rotate 90 degrees). Loosen valve adjusting screw lock nuts and adjust valve clearances on cylinder No. 2. Tighten valve adjusting screw lock nut to 14 ft. lbs. (20 N.m) and recheck valve clearance. Repeat adjustment if necessary. Reinstall cylinder head cover and ensure crankshaft pulley bolt is tightened to 181 ft. lbs. (245 N.m).

1. Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Ensure idle speed is within specification. See «IDLE SPEED»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments__idle-speed-inspection-adjustment) under IDLE SPEED & MIXTURE. Connect Honda PGM tester to Data Link Connector (DLC). Select SCS menu option and follow scan tool instructions.
2. MDX, connect inductive timing light to test loop, located at No. 1 ignition coil (may be identified with White tape). 3.2CL & 3.2TL connect inductive timing light to No. 1 ignition coil wire. Aim timing light toward pointer on timing belt cover. Red mark on crankshaft pulley should align with pointer on front of engine. (Scheme 3)
3. If timing is not as specified (Red mark and pointer are not aligned), replace ECM/PCM. Timing is not adjustable.

RSX

1. Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Ensure idle speed is within specification. See «IDLE SPEED»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments__idle-speed-inspection-adjustment) under IDLE SPEED & MIXTURE. Connect Honda PGM tester to Data Link Connector (DLC). Select SCS menu option and follow scan tool instructions.
2. Connect inductive timing light to test loop, located at No. 1 ignition coil (may be identified with White tape). Red mark on crankshaft pulley should align with pointer on timing belt cover. (Scheme 4)
3. If timing is not as specified (Red mark and pointer are not aligned), replace ECM/PCM. Timing is not adjustable. Remove PGM tester from DLC.

3.5RL

1. Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Locate 2-pin service check connector (under glove box). Install Service Check Connector Tool (07PAZ-0010100) into service check connector. (Scheme 2)
2. Ensure idle speed is within specification. See «IDLE SPEED»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments__idle-speed-inspection-adjustment) under IDLE SPEED & MIXTURE. Remove engine cover and connect inductive timing light to test loop, located at No. 1 ignition coil (may be identified with White tape). Aim timing light toward pointer on timing belt cover. Red mark on crankshaft pulley should align with pointer on front of engine. (Scheme 5) If timing is not as specified (Red mark and pointer are not aligned), replace ECM/PCM. Timing is not adjustable. Remove service check connector tool from service check connector.

Scheme 2

Scheme 3

Scheme 4

Scheme 5

IGNITION TIMING (Degrees BTDC - RED MARK @ RPM)

IDLE SPEED INSPECTION & ADJUSTMENT

Note. Before setting idle speed, ensure MIL is off, no DTCs are stored, ignition timing is correct, spark plugs and air cleaner are okay, and PCV system is operating properly.

Note. On models equipped with Daytime Running Lights (DRL), apply parking brake, and with engine running, ensure headlights are off.

Note. Adjust idle using PGM tester procedure if possible. If not, use following procedure.

RSX, 3.2CL & 3.2TL

1. Disconnect EVAP canister purge valve 2-pin connector. DO NOT disconnect Idle Air Control (IAC) valve connector. Connect a tachometer to Natural 2-pin test connector. On all models except RSX, connector is located under hood at left strut tower. On RSX, connector is located forward of under-hood fuse-relay box. For connector view (Scheme 7) Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle.
2. Turn off all electrical loads and check idle speed. See «IDLE SPEED SPECIFICATIONS»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments) table. If idle speed is incorrect on all models except RSX, turn idle adjusting screw to correct idle. Recheck idle speed after each 1/4-turn of idle adjusting screw. If idle speed is incorrect on RSX, idle speed is not adjustable. Reconnect EVAP purge control solenoid valve 2-pin connector and go to «SYMPTOMS»(ref-151688-S33584060062003010600000) in TROUBLE SHOOTING - NO CODES article.
3. Turn blower motor switch to high and A/C on, then let engine idle for one minute. Recheck idle speed. If necessary, turn idle adjusting screw to correct idle. DO NOT turn idle adjusting screw when A/C is on. Recheck idle speed after each 1/4 turn of idle adjusting screw. If idle speed is not as specified, go to «SYMPTOMS»(ref-151688-S33584060062003010600000) in TROUBLE SHOOTING - NO CODES article. Reconnect EVAP purge control solenoid valve 2-pin connector.

MDX

Checking Idle Speed - Before checking idle speed, check the following

1. The malfunction indicator lamp (MIL) has not been reported on.
2. Ignition timing.
3. Spark plugs.
4. Air cleaner.
5. PCV system.
6. On Canadian models, press the parking brake pedal. Start engine and make sure headlights are off.

Disconnect EVAP canister purge valve 2-pin connector. Connect Honda PGM Tester or the HDS to DLC. Start engine and run at 3000 RPM, with no load, (A/T in Park or Neutral), until radiator fan comes on. Allow engine to idle. Check idle speed with no loads, blower fan, radiator fan, A/C, headlights and rear window defogger off. See

IDLE SPEED SPECIFICATIONS

. Let engine idle for 1 minute with heater fan switch on HI and A/C on. Then recheck idle speed. If idle speed is not as specified, go to

SYMPTOMS TROUBLESHOOTING INDEX

. Reconnect EVAP canister purge valve 2-pin connector.

SYMPTOM TROUBLESHOOTING INDEX

Throttle Cable Adjustment - For throttle cable adjustment do the following

1. Remove the bolts and throttle cable cover.
2. Check cable free play at throttle linkage. Cable free play should be 3/8-1/2" (10-12 mm).
3. If free play is not within specification, loosen locknut, turn the adjusting nut until the deflection is as specified, then re tighten nut.
4. With cable properly adjusted, check throttle valve to be sure it opens fully when accelerator pedal is fully depressed to the floor. Also check that throttle valve closes fully when accelerator pedal is released.

Scheme 6

Scheme 7

Scheme 8

1. Connect scan tool to DLC or inductive tachometer to ignitor secondary loop (White taped). A tachometer signal can also be obtained from Natural 2-pin test connector, located at right rear corner of engine compartment. (Scheme 6)- (Scheme 7).
2. Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Disconnect Idle Air Control (IAC) valve connector. (Scheme 8) If engine stalls, restart engine with throttle slightly depressed. Stabilize RPM at 1000 and slowly release accelerator until engine idles. Turn headlights on HIGH and rear window defogger ON. Check base idle speed with transmission in Neutral or Park, with blower fan, cooling fan and A/C off. See «IDLE SPEED SPECIFICATIONS»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments) table.
3. If necessary, turn idle adjusting screw to correct idle. (Scheme 9) If idle adjustment is required, recheck ignition timing. Turn ignition off and reconnect IAC valve 2-pin connector. Remove BACK-UP (RADIO) fuse (7.5-amp) in main underhood fuse box for 10 seconds to reset ECM/PCM. Start engine and run at 3000 RPM, with no loads and transmission in Park or Neutral, until radiator fan comes on.
4. Allow engine to idle for five minutes with A/C, headlights and rear window defogger off. Check curb idle speed with transmission in Neutral or Park, with no loads and cooling fan off. See «IDLE SPEED SPECIFICATIONS»(/acura/mdx/i-2000-2006/remont/adjustments/#engine-controls-on-vehicle-adjustments) table. If idle speed is not as specified, go to «SYMPTOMS»(ref-151688-S33584060062003010600000) in TROUBLE SHOOTING - NO CODES article.

IDLE SPEED SPECIFICATIONS

Scheme 9

IDLE MIXTURE

Note. Idle mixture is computer controlled and is not adjustable.

IDLE CO LEVEL

See also:
• PCM IDLE LEARN PROCEDURE
• VALVE CLEARANCE ADJUSTMENT
• IDLE SPEED