1994 MAZDA MX-5 engine

ENGINE TUNE-UP 8. If the marks are not aligned, remove the ignition coil bracket and push the ignition coil aside for easy access and then loosen the crankshaft position sensor lock bolts, and turn the crankshaft position sensor to make the adjustment. 9. Tighten the distributor lock bolts to the specified torque. Tightening torque: 19-25 N-m (1.9-2.6 kgfem, 14--18 ftqlbf) 10. After adjusting the ignition timing, disconnect the jumper wire or SST from the data link connector. 11. Increase the engine speed and verify that the ignition timing advances. 12. Verify that the ignition timing is within the specification. Ignition timing: BTDC 6-18' ldle Speed 1. Perform Preparation. (Refer to page F-76.) 2. Set switch A to position 1. 3. Set test switch to SELF TEST. 4. With the coolant fan off, verify that the idle speed is within specification. ldle speed (Neutral): 800-900(850 + 50) rpm [MT] (P range): 750--850(800 -c 50) rpm [AT] 5. If not within the specification, adjust the idle by turning the air adjusting screw. 6. Disconnect the SST. Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM ON-BOARD DIAGNOSIS SYSTEM DESCRIPTION When troubles occur in the main input devices or output devices, check for the cause using the SST. Q Failures of each input and output device are indicated and retrieved from the powertrain control module (engine) as diagnosis trouble code numbers. Note For input devices, the PCME continuously checks for malfunctions. For output devices, it checks for malfunctions only in a three-second period after the ignition switch is turned to ON, or the TEN termi- nal of the data link connector is grounded. - INPUT SIGNALS POWERTRAIN CONTROL MODULE (ENGINE) I- -t INPUT DEVICES FAIL-SAFE FUNCTION . ON-BOARD ,, DIAGNOSIS -+ SYSTEM - - 1 I I MALFUNCTIQN DISPLAY FUNCTION -t b P v C-- MONITOR FUNCTION u SYSTEM SELF-DIAGNOSIS SELECTOR CHECKER I CHECK Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM PREPARATION SST 1 SELECT SW A STEM SELECT 1 * SYSTEM SEUC . TEST SW - SYSTEM SELECT i # SELF TEST DIAGNOSTIC TROUBLE CODE NUMBER Inspection procedure 1. Connect the SSTs to the data link connector and a ground. 2. Set the select switch to position A. 49 B019 9AO System Selector 3. Set the System Selector to position 1 and SELF TEST as shown. For diagnosis 4. Turn the ignition switch ON. 5. Verify that 88 flashes on the digital display and that the buzzer sounds for 3 sec. after turning the ignition switch ON. 6. If 88 does not flash, check the main relay (Refer to page F-156.), power supply circuit, and check connector wir- mg. 7. If 88 flashes and the buzzer continues for more than 20 sec., check for a short circuit between the powertrain control module (engine) terminal 1 E and the data link connector. Replace the powertrain control module (en- gine) if necessary and perform Steps 3 and 4 again. 8. Note any code numbers and check for the causes by re- ferring to the check sequences shown on pages F-83 to F-93. Repair as necessary. 9. After repairs, cancel the code numbers by performing the "After-repair procedure". (Refer to page F-94.) Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM F Code Numbers Malfunction display On-board diagnosis system Code No. 0 1 03 Pattern of output signal (Self-Diagnosis System Checker) Sensor or subsystem IGF signal SGT signal Fail-safe ON OFF A-n-L ON OFF m No SGT signal ON OFF JuUu Cancels fuel injection No SGC signal Cancels fuel injection and electronic spark distribution SGC signal Basic fuel injection amount fixed as for two driving modes (1) ldle switch: ON (2) ldle switch: OFF ON OFF Mass airflow sensor Open or short circuit Engine coolant tempera- ture sensor ON OFF -JLnn Open or short circuit Intake air temperature sen- sor (Mass airflow sensor) Maintains constant 35°C {95"F} command Maintains constant 20°C {68"F} command Open or short circuit ON OFF -nNLnM- Maintains constant com- mand of throttle valve wide open throttle Throttle position sensor Open or short circuit ON OFF Barometric absolute pres- sure sensor Maintains constant command of sea level pressure Open or short circuit Heated oxygen sensor (Inactivation) EGR function sensor Sensor output continues less than 0.55V 180 sec. after engine exceeds 1,500 rpm Cancels engine closed loop operation ON OFF ON OFF --nMM.A ON OFF --rMMMA Open or short circuit Heated oxygen sensor (In- version) Maintains constant command of EGR valve ON OFF JlnMkm Sensor output continues unchanged 20 sec. after engine exceeds 1,500 rpm PRC solenoid valve Cancels engine closed loop operation Open or short circuit Open or short circuit I - ON OFF m Purge solenoid valve ON OFF EGR solenoid valve (vacu- um) ON OFF Open or short circuit EGR solenoid valve (vent) ldle air control valve - Open or short circuit ON OFF m Open or short circuit I - Gartner Banana

F ON-BOARD DIAGNOSIS SYSTEM CODE No. ACTION Yes I Repair or replace connector 08 (MASS AIRFLOW SENSOR) iTEP 1 No I Go to next step INSPECTION Are there any poor connections in mass airflow sensor circuit? Yes 2 Check for open circuit in wiring from mass airflow sensor terminal E to wound Is Code No.10 present at same time? No ( Go to next step 1 Is there continuity between mass airflow sensor connector and PCME? Yes Go to next step Mass airflow sensor E B I Yes I Replace PCME . us page F-143 PCME 2F 20 No Check for short circuit in wiring from mass airflow sensor to PCME Are PCME terminals 20 and 2F voltages OK? page F-146 Check for open circuit in wiring from mass airflow sensor to PCME CODE No. ACTION 09 (ENGINE COOLANT TEMPERATURE SENSOR) STEP 1 Repair or replace connector Go to next step INSPECTION Are there any poor connections in engine coolant temperature sensor circuit? Go to next step Yes - No 2 Engine coolant temperature sensor PCME Check for open circuit in wiring from engine coolant tem- perature sensor to PCME Is there continuity between engine coolant temper- ature sensor and PCME? 4 Is resistance of engine coolant temperature sensor 1 /om I yes Yes Go to next step Coolant temp. Resistance 1 I 20°C ( 68°F) 1 2.21-2.69 kR Replace engine coolant temperature sensor page F-154 Is same Code No. present after performing after repair procedure? page F-94 Go to next step Engine coolant temperature sensor and circuit OK Are PCME terminals 2Q and 2D voltages OK? page F-146 Re~lace PCME ~aae F-143 Check for short circuit in wiring from engine coolant tem- perature sensor to PCME Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM I CODE No. I -- -- 10 (INTAKE AIR TEMPERATURE SENSOR - IN MASS AIRFLOW SENSOR) INSPECTION Are there any poor connections in intake air tem- Yes perature sensor circuit? No Is there continuity between intake air temperature Yes sensor (in mass airflow sensor) and PCME? Intake air temperature sensor PCME I D 2 P Is resistance of intake air temperature sensor (in Yes mass airflow sensor) OK? Terminal I Temperature I Resistance No C-D I 20°C {68"F) 1 2.21-2.69 kR Is same Code No. present after performing after Yes repair procedure? page F-94 No Are powertrain control module (engine) terminals 2P and 2D voltages OK? @= page F-146 ACTION Repair or replace connector Go to next step Go to next step Check for open circuit in wiring from intake air temperature sensor (in mass airflow sensor) to PCME Go to next step Replace mass airflow sensor @= page F-152 -- Go to next step Intake air temperature sensor and circuit OK Replace PCME IS= page F-143 Check for short circuit in wiring from intake air temperature sensor to PCME CODE No. 12 (THROTTLE POSITION SENSOR) I Check throttle position sensor circuit for poor con- nection Throttle position sensor PCME D 2K 2 Repair or replace STEP 1 INSPECTION Yes No ACTION Repair or replace connector Go to next step Check wire harness between throttle position sen- sor and PCME for continuity 3 Replace PCME IS= page F-143 15UOFX-032 Yes CODE No. Go to next step 35UOFX-04 Check if PCME terminal 2M voltage is OK page F-146 14 (BAROMETRIC ABSOLUTE PRESSURE SENSOR) Yes No Replace PCME I@= page F-143 Check for short circuit in wiring from throttle position sen- sor to PCME Gartner Banana

F ON-BOARD DIAGNOSIS SYSTEM CODE No. 15 (HEATED OXYGEN SENSOR: INACTIVATION) 111 Are there any poor connections in heated oxygen sensor circuit? Note a If Code Nos.15 and 17 are both present, first perform the checking procedure for Code No.17 STEP 1 INSPECTION I ACTION 2 3 Circuit Diagram I Yes No 4 5 ENGINE COOLANT MASS AIRFLOW TEMPERATURE SENSOR SENSOR ~ Repair or replace connector Go to next steD Is heated oxygen sensor output voltage OK? page F-155 Is there continuity between heated oxygen sensor and PCME terminal 2N? THROTTLE POSITION SENSOR 35UOFX-065 Is PCME terminal 2N voltage OK? Is sensitivity of heated oxygen sensor OK? * page F-156 PCME Yes No Yes No Go to next step Replace heated oxygen sensor r@ page F-156 Go to next step Check for open circuit in wiring from heated oxygen sen- sor to PCME Yes No Yes No Go to next step Check for short circuit in wiring from heated oxygen sen- sor to PCME Replace PCME aPi. page F-143 Replace heated oxygen sensor r@ page F-156 Gartner Banana

F ON-BOARD DIAGNOSIS SYSTEM CODE No. 17 (HEATED OXYGEN SENSOR: INVERSION) I Circuit Diagram INSPECTION Warm up engine and run it at 2,500-3,000 rpm for 3 min. HEATED OXYGEN SENSOR ACTION Does monitor lamp of Self-Diagnosis Checker illu- minate at idle? Are spark plugs clean? Is heated oxygen sensor voltage OK? * page F-156 Is same Code No. present after performing after repair procedure? ESI= page F-90 Is there continuity between heated oxygen sensor and PCME terminal 2N? Is PCME terminal 2N voltage OK? * page F-146 PCME Yes No Yes No Yes No Yes No Yes No Yes No Go to next step Check for air leak in vacuum hoses or emission compo- nents Check for contaminated heated oxygen sensor Check for insufficient fuel injection Go to next step Clean or replace spark plugs Go to next step Replace heated oxygen sensor page F-156 Go to next step Check for short circuit in wiring from heated oxygen sen- sor to PCME terminal 2N Go to next step Check for open circuit in wiring from heated oxygen sen- sor to PCME Replace PCME page F-143 Check for short circuit in wiring from heated oxygen sen- sor to PCME Gartner Banana