Engine Controls - On-Vehicle Adjustments: Other Mazda MX-5 NB

ENGINE MECHANICAL

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

Miata, Protege & 626 2.0L

1. Remove valve cover. Ensure engine is cold. Rotate crankshaft clockwise until No. 1 piston is at TDC of compression stroke. Measure valve clearance between base of camshaft lobe and valve tappets at "A". (Scheme 4) See «VALVE CLEARANCE SPECIFICATIONS»(ref-91091-S30971266632001030200000) table. If clearance is not within specification, replace adjustment shim. Go to step 3.
2. Rotate crankshaft clockwise about 360 degrees positioning No. 4 piston at TDC of compression stroke. Measure valve clearance between base of camshaft lobe and valve tappets at "B". (Scheme 4) See «VALVE CLEARANCE SPECIFICATIONS»(ref-91091-S30971266632001030200000) table. If clearance is not within specification, replace adjustment shim. Go to step 3.
3. Turn crankshaft clockwise so that camshaft lobe on valve requiring clearance adjustment is positioned straight up, away from valve. Remove appropriate camshaft cap bolts as necessary. (Scheme 5) See «CAMSHAFT BOLT REMOVAL»(ref-91091-S17808879932001030200000) table. NOTE: For No. 2 and 3 cylinder exhaust valve adjustment shim removal, remove bolt "A" or "C". For No. 2 and 3 cylinder intake valve adjustment shim removal, remove bolt "B" or "D".
4. Assemble Adjustment Tool Shaft and Clamp (49-T012-002 and 49-T012-003), aligning marks on adjustment tools. (Scheme 6) Install shaft and clamp on appropriate camshaft using camshaft cap bolts. Tighten cap bolts to 100-125 INCH lbs. (11.3-14.1 N.m). (Scheme 7) Tighten clamp bolt to secure shaft.
5. Position Body (49-T012-001) toward center of cylinder head. Mount body on shaft at point of adjustment shim to replaced. (Scheme 7) Position notch of tappet so that thin-bladed screwdriver can be inserted. (Scheme 8) Set body on tappet and align by its notch. Tighten short bolt to secure body to shaft. CAUTION: Use caution when depressing tappet. Cylinder head can be damaged by body tip when tappet is depressed.
6. Tighten long bolt on body to depress tappet. Using thin-bladed screwdriver, pry up on adjustment shim through notch on tappet. Using a magnet, remove shim and measure shim thickness. Select proper adjustment shim to obtain clearance within specification. Push selected shim into tappet. Loosen long bolt to allow tappet to move up. Loosen short bolt and remove body. Remove shaft and clamp. Install camshaft cap bolts and tighten to 100-125 INCH lbs. (11.3-14.1 N.m). Recheck valve clearance.

VALVE CLEARANCE SPECIFICATIONS

CAMSHAFT BOLT REMOVAL

Scheme 4

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

1. Remove intake manifold and valve covers. See REMOVAL, OVERHAUL & INSTALLATION article. Ensure engine is cold. Rotate crankshaft clockwise until No. 1 piston is at TDC of compression stroke. Measure valve clearance between camshaft lobe and valve tappet of both banks at "A". (Scheme 9) If clearance is not within specification, replace adjustment shim. See «VALVE CLEARANCE SPECIFICATIONS»(ref-91091-S30971266632001030200000) table.
2. Rotate crankshaft clockwise about 240 degrees positioning No. 3 piston at TDC of compression stroke. Measure valve clearance between base of camshaft lobe and valve tappet of both banks at "B". (Scheme 9) If clearance is not within specification, replace adjustment shim. See «VALVE CLEARANCE SPECIFICATIONS»(ref-91091-S30971266632001030200000) table.
3. Rotate crankshaft clockwise about 240 degrees positioning No. 5 piston at TDC of compression stroke. Measure valve clearance between base of camshaft lobe and valve tappet of both banks at "C". (Scheme 9) If clearance is not within specification, replace adjustment shim. See «VALVE CLEARANCE SPECIFICATIONS»(ref-91091-S30971266632001030200000) table.
4. Turn engine clockwise until camshaft lobe of valve requiring adjustment is pointing straight up. Remove appropriate camshaft cap bolts for valves requiring adjustment. See «CAP BOLT IDENTIFICATION»(ref-91091-S19181121392001030200000) table. CAP BOLT IDENTIFICATION Cap Bolts (1) Application No. 1 Right Cyl. Head Exhaust Valves No. 2 Right Cyl. Head Intake Valves No. 3 Left Cyl. Head Exhaust Valves No. 4 Left Cyl. Head Intake Valves (1) (Scheme 10)
5. Install Tappet Holder (49 T012 0A0), with body toward center of cylinder head, to camshaft caps where bolts were removed. Tighten tappet holder bolts to 99-125 INCH lbs. (11.3-14.2 N.m). Align bolts to secure shaft after alignment.
6. Rotate notch in tappet so small screwdriver can be inserted. Position tappet holder body over tappet that requires shim replacement. Tighten holder body to shaft. Tighten holder bolt to compress tappet.
7. Using small screwdriver, pry shim from tappet. Using magnet, remove shim. Measure shim. Change to appropriate shim thickness to meet valve clearance specification.
8. Loosen bolt compressing tappet. Remove tappet holder assembly. Reinstall camshaft cap bolts and tighten to specification. Recheck valve clearance. Install valve cover with NEW gasket. Install intake manifold. See REMOVAL, OVERHAUL & INSTALLATION article.

Scheme 10

IGNITION TIMING

Note. Before adjusting ignition timing, warm engine to normal operating temperature. Turn off all accessories. Place transmission in Neutral (M/T) or Park (A/T). Wait for cooling fan to stop. Ensure idle speed is correct. See IDLE SPEED under IDLE SPEED & MIXTURE.

MILLENIA & PROTEGE

Note. On Millenia 2.3L, ignition timing is not adjustable.

Scheme 11

1. Connect New Generation Star (NGS) scan tool to Data Link Connector (DLC) 2 located under left side of instrument panel, right of steering column. (Scheme 12) Connect a jumper wire between terminals TEN and GND at DLC 1 in engine compartment. (Scheme 13)
2. Ensure idle speed is correct. See «IDLE SPEED»(ref-91091-S25956493402001030200000) under IDLE SPEED & MIXTURE. On all models except Millenia 2.3L, connect timing light to high-tension lead No. 1. On Millenia 2.3L, connect Inductive Timing Light (49-T018-002) lead to ignition timing checking harness (Black/White wire) located next to engine compartment relay box. (Scheme 11) Start engine and allow it to idle. Check timing. See «IGNITION TIMING SPECIFICATIONS»(ref-91091-S15524031552001030200000) table. (Scheme 14) NOTE: Standard inductive timing light may not work on ignition timing checking harness. Recommend using manufacturers Inductive Timing Light (49-T018-002) or equivalent
3. On Millenia 2.3L, if ignition timing is not within specification, check for diagnostic trouble codes. See appropriate SELF-DIAGNOSTICS article. Repair as necessary. If no codes are present, check Camshaft Position (CMP) sensor and Crankshaft Position (CKP) sensor. See SYSTEM & COMPONENT TESTING - EXCEPT B2500, B3000 & B4000 article. Replace as necessary.
4. On all models except Millenia 2.3L, if ignition timing is not within specification, loosen distributor lock bolt. Rotate distributor until timing marks align. Tighten lock bolt. Recheck timing.

626

1. Connect New Generation Star (NGS) scan tool to data link connector 2 located under left side of instrument panel, right of steering column. (Scheme 12) Ensure idle speed is correct. See «IDLE SPEED & MIXTURE»(ref-91091-S00214072112001030200000).
2. Connect timing light to engine and check timing. (Scheme 14) See «IGNITION TIMING SPECIFICATIONS»(ref-91091-S15524031552001030200000) table. If ignition timing is not within specification, check CMP sensor, CKP sensor, TP sensor, ECT sensor, neutral switch, clutch switch and transmission range switch. See SYSTEM & COMPONENT TESTING - EXCEPT B2500, B3000 & B4000 article. If all sensors and switches are okay, replace PCM.

IGNITION TIMING SPECIFICATIONS (Degrees BTDC @ RPM)

Scheme 12

Scheme 13

Scheme 14

IDLE SPEED & MIXTURE

Note. Idle mixture is not adjustable. If idle mixture is incorrect, see appropriate SELF-DIAGNOSTICS article.

COLD (FAST) IDLE SPEED

Note. Fast idle speed is computer controlled. Adjustment is not necessary.

IDLE SPEED

Note. Before adjusting idle speed, warm engine to normal operating temperature. Turn off all accessories. Place transmission in Neutral (M/T) or Park (A/T). Wait for cooling fan to stop. DO NOT adjust idle using throttle adjusting screw. Throttle adjusting screw is preset and if adjusted, will adversely affect engine performance.

1. Connect New Generation Star (NGS) scan tool to Data Link Connector (DLC) 2 located under left side of instrument panel, right of steering column. (Scheme 12) Connect a jumper wire between terminals TEN and GND at data link connector in engine compartment. (Scheme 13)
2. Start engine and allow it to idle. Using scan tool, select PID/DATA MONITOR AND RECORD and monitor RPM. If idle speed is not within specification, rotate air adjusting screw on throttle body. (Scheme 15) See «IDLE SPEED SPECIFICATIONS»(ref-91091-S37416612382001030200000) table.

1. Connect New Generation Star (NGS) scan tool to data link connector 2 located under left side of instrument panel, right of steering column. (Scheme 12) Start engine and allow it to idle. Select PID/DATA MONITOR AND RECORD. Trigger function.
2. Select RPM and press trigger. Select START. See «IDLE SPEED SPECIFICATIONS»(ref-91091-S37416612382001030200000) table. If idle speed is not within specification, select HDLMP under PID/DATA MONITOR AND RECORD. Trigger function. Verify HDLMP status changes from OFF to ON when operating stalk switch (passing position). If HDLMP status changes, go to next step. If HDLMP status does not change, see appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT.
3. Connect inductive-type tachometer. Select DIAGNOSTIC TEST MODES. Trigger function. Select KOER ON-DEMAND SELF-TEST. Trigger function. Operate stalk switch to high beam (passing) position. Once scan tool displays FOR EXAMPLE BOO, PSP AND TCS, wait 2 seconds and switch head lights to low beam. Repeat process 2 more times. Within 2 minutes, adjust idle speed to specification. (Scheme 15) See «IDLE SPEED SPECIFICATIONS»(ref-91091-S37416612382001030200000) table.

IDLE SPEED SPECIFICATIONS

Scheme 15

THROTTLE POSITION (TP) SENSOR

Note. DO NOT adjust throttle adjusting screw. Throttle adjusting screw is preset and if adjusted, will adversely affect engine performance.

Millenia & 626 2.5L

Closed throttle position switch is part of Throttle Position (TP) sensor, which is adjusted automatically when TP sensor is adjusted. See THROTTLE POSITION (TP) SENSOR .