engine MAZDA MX-5 1994 Workshop Manual

CONTROL SYSTEM 1 1 USE CONNECTOR A CRANKSHAFT POSITION SENSOR Inspection 1. Remove the crankshaft position sensor 5v- - - - SGGSIGNAL ov Warning Disconnect the fuel injector connector. When checking the crankshaft position sensor, do not connect the igniter connector - - - - I 1 CYCLE < > 2. Connect the crankshaft position sensor shown in figure. 3. Disconnect the fuel injector connector. 4. Turn the ignition switch ON. 5. Connect the SSTs (Engine Signal Monitor and Adapter Harness) to the PCME. 6. Set the SST (Engine Signal Monitor) as shown below. 7. Rotate the sensor drive by hand and measure the output voltage. Specification I 1 - Position - ~oltaael 8. After the inspection, install the crank angle sensor. 9. Start the engine and adjust the ignition timing. (Refer to page F-76.) 2E (SGT signal) 2G (SGC signal) Ignition timing: BTDC 10 2 1" Approx. 5V (4 pulseslrev) Approx. 5V (2 pulseslrev) 10. Tighten the crank angle sensor lock bolt to the specified torque. Tightening torque: 19-25 N-m (1 .+2.6 kgfem, 14-1 8 ftelbf} Replacement 1. Remove the ignition coil. (Refer to section G.) 2. Remove in the order shown in the figure. 3. Install in the reverse order of removal. Gartner Banana

CONTROL SYSTEM TEMPERATURE NGlNE COOLANT EMPERATURE ENGINE COOLANT TEMPERATURE SENSOR Removal 1. Remove the ignition coil assembly. (Refer to section G.) 2. Disconnect the engine coolant temperature sensor con- 4 nector. 3. Remove the engine coolant temperature sensor. lnspection 1. Place the sensor in water with a thermometer and heat the water gradually. 2. Measure resistance of the sensor with an ohmmeter. 3. If not as specified, replace the engine coolant tempera- ture sensor. Specification DCBA Coolant 20°C {68"F) 80°C {I 76°F) FEELER GAUGE Resistance kR 2.21 - 2.69 0.287- 0.349 Installation 1. Install the engine coolant temperature sensor and a new washer. Tightening torque: -J 25-29 N.m (2.5-3.0 kgf-m, 19--21 ft-lbf) 2. Connect the engine coolant temperature sensor con- nector. 3. Install the ignition coil assembly. (Refer to section G.) THROTTLE POSITION SENSOR lnspection Idle switch 1. Turn the ignition switch OFF and the throttle valve closed throttle position. 2. Disconnect the throttle position sensor connector. 3. Check continuity of the throttle position sensor terminals C and D. I C-D I Continuity 4. If not as specified, adjust the throttle position sensor. (Refer to page F-155.) 5. Insert a feeler gauge 0.4 mm {0.016 in) between the stopper and the throttle lever. 6. Verify that no continuity the throttle position sensor ter- minals C and D. - 7. If continuity, adjust the throttle position sensor. (Refer to page F-155.) Specification Terminals Throttle valve closed throttle ~osition Gartner Banana

CONTROL SYSTEM DCB IIIf I 1 USECONNECTORA I Variable resister 1. Remove the PCME. (Refer to page F-143.) 2. Connect the SSTs (Engine Signal Monitor and Adapt- er Harness) to the PCME. 3. Set the SST (Engine Signal Monitor) to position 2M. 4. Turn the ignition switch ON. 5. Rotate the throttle link by hand and verify that voltage is within the specification. Specification 6. If not as specified, adjust the throttle position sensor. (Refer to below.) - PCME terminal Adjustment Throttle valve position I Wide open throttle ~osition Note The throttle adjusting screw is set at the factory and must not be adjusted. Any adjustment will negatively effect the engine per- formance. Idle switch 1. Turn the ignition switch OFF and the throttle valve closed throttle position. 2. Disconnect the throttle position sensor connector. 3. Loosen the throttle position sensor screws. 4. Rotate the throttle position sensor and adjust continuity of the sensor terminals C and D as shown. Specification I Clearance Continuity I 5. Tighten the throttle position sensor screws. 0.3 mm (0.012 in} Tightening torque: 1.6-2.3 N.m (16-24 kgf-m, 14--20 in-lbf) Yes Variable resister 1. Remove the PCME. (Refer to page F-143.) 2. Connect the SSTs to the PCME connector as shown. 3. Verify that the throttle valve is fully closed. 4. Loosen the attaching screws. 5. Turn the ignition switch to ON. 6. Measure the PCME terminal 2M voltage. 7. Adjust the voltage to the specification 0.4 mm (0.01 6 in) I No Gartner Banana

CONTROL SYSTEM SENSOR CONNECTOR EATED OXYGEN Specification Fully closed: 0.1-1.1 V Fully open: 3.14.5V (Verify that the voltage increase is directly d propotioned to the throttle valve opening angle.) 8. Tighten the attaching screws. Tightening torque: 1.6-2.3 N.m (16-24 kgfmm, 14-20 in-lbf} 9. If not adjusted, replace the throttle position sensor. 45UOFX-495 Replacement 1. Turn the ignition switch OFF. 2. Remove the throttle position sensor screws. 3. Remove the throttle position sensor . 4. Replace a new throttle position sensor and adjust it. (Refer to page F-155.) 5. Tighten the throttle position sensor screws. Tightening torque: 1.6-2.3 N.m (16-24 kgf-cm, 14-20 in-lbf} HEATED OXYGEN SENSOR Inspection On-vehicle 1. Warm-up the engine to normal operating temperature and run it at idle. 2. Disconnect the heated oxygen sensor connector. -.-' 3. Measure the voltage at terminal A. 4. If not as specified, check the intake air system, the fuel system and run the on-board diagnosis test. 5. If these system are OK, replace the heated oxygen sen- sor. Specification Heater 1. Disconnect the heated oxygen sensor connector. 2. Measure resistance between terminals C and D. Resistance: Approx. 13R (20°C (68°F)) Engine condition Terminal A 3. Replace the heater if not as specified. Increasing engine speed (V) 0.&1 .O Idle Below 1.0 Replacement 1. Disconnect the heated oxygen sensor connector. 2. Remove the heated oxygen sensor. 3. Install in the reverse order of removal. Decreasing engine speed (V) 0-0.4 Tightening torque: 3049 N-m (3.0-5.0 kgf-m, 22-36 ftlbf) Gartner Banana

CONTROL SYSTEM Replacement Replace the neutral switch as shown in the figure. STEERING PRESSURE SENSOR Inspection 1. Disconnect the steering pressure sensor connector. 2. Connect an ohmmeter to the switch. 3. Start the engine and let it idle. Check continuity of the switch while turning the steering wheel. PIS 1 Continuity Turnina Yes " I t ~ot turning I NO 4. If not as specified, replace the steering pressure sensor. Replacement Replace the steering pressure sensor as shown in the figure. Gartner Banana

Before beginning any service procedure. refer to section T of this manual for air bag system service warnings and audio antitheft system alarm conditions . ENGINE ELECTRICAL SYSTEM INDEX ....................................... G- 2 OUTLINE ..................................... G- 3 SPECIFICATIONS ........................... G- 3 TROUBLESHOOTING GUIDE .................. G- 4 CHARGING SYSTEM .......................... G- 6 PREPARATION ............................. G- 6 CIRCUIT DIAGRAM ......................... G- 6 TROUBLESHOOTING ....................... G- 7 BATTERY .................................. G- 8 ALTERNATOR .............................. G-10 DRIVE BELT ................................ G-13 IGNITION SYSTEM ............................ G-15 PREPARATION ............................. G-15 CIRCUIT DIAGRAM ......................... G-15 TROUBLESHOOTING ....................... G-16 IGNITION TIMING ........................... G-17 SPARK PLUG ............................... G-18 IGNITION COIL ............................. G-19 IGNITER ................................... G-19 HIGH-TENSION LEAD ....................... G-20 STARTING SYSTEM ........................... G-21 CIRCUIT DIAGRAM ......................... G-21 TROUBLESHOOTING ....................... G-21 STARTER .................................. G-22 STARTER INTERLOCK SWITCH (MT) ......... G-28 45UOGX401 Gartner Banana

OUTLINE OUTLINE SPECIFICATIONS (i.e. powertrain control module (engine), audio, etc.) *2 With System Selector (49 B019 9AO) test switch at SELF TEST. - Engine Item Starter Ignition system Cylinder Arrangement Battery BP DOHC MT I AT 12, Negative ground S46A24L(S) (32 Ah) Maintenance-free 20.0 A.C. I REAR Voltage V Type and capacity (5-hour rate) 12-65 -. 1 2-70 Drive belt deflection mm {in} Dark current" m A Transistorized (built-in voltage regulator) 14.3-1 4.9 21.5 I0.846) 8 (0.31 1 Ignition timing** BTDC ("CA)lrpm U Alternator 'I Dark current is the constant flow of current while the ignition switch is OFF. 45UoGX-003 New Used 101850 Ignition coil Spark plug FRONT 55-7.0 (0.22-0.27) 6.0-7.5 (0.2H.29) 101800 TY pe Primary coil winding n Secondary coil winding kR Type Plug gap mm {in) Firing order Type Output V-A Regulator type Regulated voltage V TY pe Output V-kW Molded (with igniter) - 8.7-1 2.9 (20°C (68°F)) NGK : BKR5E-11 BKR6E-11 (Standard ... MT) NIPPONDENSO : K16PR-U11 K20PR-U11 (Standard ... MT, AT) 1 .O-1.1 IO.040-0.043) 1-3-4--2 Brush length mm {in) Direct 124.95 17.0 i0.67) 11.5 I0.45) Brush length mm {in} Standard Minimum Coaxial reduction 12-1.4 17.5 i0.69) 12.0 i0.47) Standard Minimum Electronic spark advance (ESA) Powertrain control module (engine) controls spark advance Type Spark advance control Gartner Banana

TROUBLESHOOTING GUIDE TROUBLESHOOTING GUIDE Problem Will not crank Cranks slowly Discharged battery Misfire G-5 Will not crank I Will not crank I Check 1 1 , YES, Check if engine cranks with fully charged battery Check charging system (Refer to page G-7) I NO Check ignition switch (Refer to section T), starter interlock switch (Refer to page G-28) and parWneutral switch (Refer to section K) 45uOOx-OC - Check 1 Check if click is heard from starter magnetic switch when ignition is turned to START Cranks slowly Check starting system (Refer to page G-21) Crank slowly Check 1 Check charging system (Refer to page G-7) I NO ---- Check starting system (Refer to page G-21) Check 1 Gartner Banana

CHARGING SYSTEM G TROUBLESHOOTING Check 1 Check if battery p Check battery (Refer to page G-8) J Check 2 I. Turn ignition switch ON Check wire harness 2. Check if voltage exists at each terminal of alternator Check 3 YES 1. Start engine Check alternator (Refer to page G-10) 2. Check if alternator warning light goes off I YES Check if drive belt t Adjust or replace drive belt (Refer to page G-14) 1 YES I Check for dark current (Refer to page G-3) I Check 1 BATTERY r"; Check 3 I ALTERNATOR WARNING LIGHT Check 2 B+: Battery positive voltage I I I B 1 Approx. 12V 1 Approx. 12V I B+ ON ON (Idle) L S 45UOGX-006 OV Approx. 12V Approx. 1V Approx. 12V B+ B+ Gartner Banana

CHARGING SYSTEM 1. Disconnect the battery cables from the battery. 2. Connect a voltmeter to the battery. BATTERY Warning Hydrogen gas is produced during normal battery d operation. A battery-related explosion can cause serious injury. Keep all flames (including ciga- rettes), heat, and sparks away from the top and surrounding area of open battery cells. Caution To prevent damage to electrical components or the battery, turn all accessories off and stop the engine before performing maintenance or re- charging the battery. Caution Obtain the code number and deactivate the audio anti-theft system before disconnecting the bat- tery. (Refer to section T.) Inspection Caution When disconnecting the battery, remove the neg- ative cable first and install it last to prevent dam- age to electrical components or the battery. Gartner Banana