1994 MAZDA MX-5 Workshop Manual

ENGINE TUNE-UP - TIMING LIGHT - 45UOFX422 GND Irnr Air Cleaner Element Inspection 1. Check the air cleaner element for excessive dirt and for oil and damage. Caution Cleaning the element with compressed air will re- duce the element's ability to filter the air. Don't use compressed air to clean the element. 2. Replace the element if necessary. ADJUSTMENT Preparation 1. Warm up the engine to normal operating temperature. 2. Turn all electric loads OFF. Headlight switch Blower switch Rear window defroster switch 3. Connect the SST to the data link connector. 4. Connect a timing light to the engine. 5. Connect a tachometer to the data link connector terminal IG- as shown. Ignition Timing 1. Perform Preparation. (Refer to above.) 2. Verify that the idle speed is within the specification; if not, adjust it. Idle speed 4 (Neutral): 800-900 (850 + 50) rpm [MT] (P range): 750-850 (800 & 50) rpm [AT] 3. Set switch A to position 1. 4. Set test switch to SELF TEST. 5. If the SST is not used, connect a jumper wire between the TEN terminal and the GND terminal of the data link connector. 6. Verify that the idle speed is within the specification. ldle speed (Ground the terminal TEN): 650-975 rpm 7. Verify that the timing mark (white) on the crankshaft pulley and the mark on the timing belt cover are aligned. lgnition timing: BTDC 9"-11" (10" & lo) Gartner Banana

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 Principle of Code Cycle Diagnostic trouble codes are determined as shown below. 1. Code cycle break The time between diagnostic trouble code cycles is 4.0 seconds (the time the lamp is off). 1 CYCLE DIAGNOSTIC I I TROUBLE CODE, CYCLE BREAK I JUU I I C-----------l 4.0 SEC. 2. Second digit of diagnostic trouble code (ones position) The digit in the ones position of the diagnostic trouble code represents the number of times the buzzer sounds 0.4 second during one cycle. I 1 1 CYCLE DIAGNOSTIC DIAGNOSTIC ON TROUBLE CODE I TROUBLE 1 2 3 CYCLE BREAK CODE: 03 UICCl4 4.0 4.0 4.0 SEC. SEC. SEC. 3. First digit of diagnostic trouble code (tens position) The digit in the tens position of the diagnostic trouble code represents the number of times the buzzer is on 1.2 seconds during one cycle. It should also be noted that the light goes off for 1.6 seconds between the long and short pulses of the buzzer. r 1 CYCLE DIAGNOSTIC DIAGNOSTIC . TROUBLE CODE TROUBLE L 12 CODE: 22 - FIRST DIGIT SECOND DIGIT 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

ON-BOARD DIAGNOSIS SYSTEM Note If more than one failure is present, the code numbers will be indicated in numerical order. After repairs, cancel the code numbers by performing the "After-repair procedure". (Refer to page F-88.) ,J Gartner Banana

ON-BOARD DIAGNOSIS SYSTEM Troubleshooting If a diagnostic trouble code number is shown on the SST, check for the cause by using the chart related to the code number shown. CODE NO. 01 (IGF-SIGNAL) 1 Are there any poor connections at ignition coil con- nectors? 2 STEP 1 INSPECTION Does tachometer operate? 3 = 1 Is there continuity between ignition coil terminal C and ground? ACTION Is resistance of ignition coil OK? Resistance: Secondary 8.7-1 2.9 kQ 4 1 Are PCME terminals 1 G and 1 H voltages OK? @s page F-145 Is ignition coil terminal A voltage OK? Section G Circuit Diagram IGNITION COIL (IGNITER) Yes 1 Repair or replace connector I No Yes Go to next step Go to next step No Yes Check for open circuit in wiring from ignition oil to PCME terminal 21 Go to next step No Yes Yes I Replace PCME page F-143 I Replace ignition coil rn Section G Go to next step No Yes No - - No I Check for circuit in wiring from ignition coil to PCME I 35UOFX-043 Check for open circuit in wiring from ignition coil to ignition switch Go to next step Check for open circuit in wiring from ignition coil to ground DATA LINK - . . . . . - . . CONNECTOR 9 3 PCME Gartner Banana