1994 MAZDA MX-5 coolant temperature

TROUBLESHOOTING GUIDE 7 CRANKS NORMALLY BUT WILL NOT START (PARTIAL COMBUSTION) -AFTER WARM-UP I ~ngine starts normally when cold TROUBLESHOOTING HINTS] D AirIFuel mixture too rich O Vapor lock Fuel pressure not held in fuel line after engine stops High RVP (winter) fuel used in warm weather 'ESCRIPTIoN Fuel injection control malfunction (Correction for coolant temperature) Fuel injector fuel leakage I INSPECTION Engine cranks at normal speed but shows partial combustion and will not continue to run after running and hol soaked Battery in normal condition :heck if "00" is displayed on Self-Diagnosis Checker with ignition switch ON @S page F-79 :heck if PCME terminal voltages are OK :2D and 20) page F-136 sonnect data link connector terminals F/P and GND ~ith jumper wire and check for correct fuel line pres- sure with ignition switch ON page F-110 Fuel Line pressure: 26-14 kPa {2.7-3.2 kgflcm2, 38-46 psi) GND F~P INSTALL CLAPS ' Yes No - Yes - No Yes ACTION Go to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME page F-143 0 If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Go to next step Check for cause (Refer to "Check Point for Each Terminal") page F-148 Go to next step Low pressure Check fuel line pressure while pinching fuel return hose Q If fuel line pressure quickly increases, check pressure regulator page F-118 0 If fuel line pressure gradually increases, check fuel line and filter for clogging If not clogged, check fuel pump maximum pressure page F-115 - High pressure Check if fuel return hose is clogged or restricted a If OK, replace pressure regulator page F-119 6 If not OK, repair or replace Gartner Banana

TROUBLESHOOTING GUIDE ESCRIPTION I 0 Engine cranks at normal speed but requires excessive cranking time (more than 5 sec.) before starting Batterv in normal condition 5 I TROUBLESHOOTING HINTS] D Air/Fuel mixture too lean Q Air/Fuel mixture too rich Fuel injection control malfunction Air cleaner element clogged (Correction for coolant temperature) Mass airflow sensor stuck Low fuel line pressure 31 Poor ignition spark CRANKS NORMALLY BUT HARD TO START - ALWAYS Air leakage STEP - 1 INSPECTION Check if "00" is displayed on Self-Diagnosis Checker with ignition switch ON page F-79 Check for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg (17.7 inHg} VA/CUUM GAUGE Check if air cleaner element is clean page F-76 Check for correct fuel line pressure at idle page F-110 Fuel line pressure: 265--314 kPa (2.7-4.2 kgf/cm2, 38--46 psi} (Vacuum hose to pressure regulator discon- nected) INSTALL CLAPS ' - Yes - No - Yes - No - Yes No - Yes - No - ACTION Go to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage page F-145 Specification: Battery positive voltage (Ignition switch ON) Q If OK, replace PCME page F-143 o If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Go to next step Check for air leakage of intake air system components page F-100 Go to next step Replace air cleaner element page F-99 Go to next step Low pressure Check fuel line pressure while pinching fuel return hose Q If fuel line pressure quickly increases, check pressure regulator page F-118 0 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure page F-115 Gartner Banana

TROUBLESHOOTING GUIDE CRANKS NORMALLY BUT HARD TO START - WHEN ENGINE IS COLD c Engine cranks at normal speed but requires excessive cranking time before starting IESCRIPTION Battery in normal condition Restarts OK after warm-up TROUBLESHOOTING HINTS] D AirIFuel mixture too rich Air cleaner element clogged Idle speed control malfunction Q AirJFuel mixture too lean Fuel injection control malfunction (Correction for coolant temperature) O Poor atomization of fuel Low RVP (summer) fuel used in cold weather INSPECTION Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 ACTION - Yes - No - Yes GO to next sGP Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) E+T page F-81 "88" flashes Check PCME terminal 1 E voltage page F-145 Specification : Battery positive voltage (Ignition switch ON) c:, If OK, replace PCME page F-143 o If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Check if PCME terminal voltages are OK (1 C, 2D, 20 and 2Q) page F-145 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") I@ page F-148 Check if engine starts easily when depressing ac- celerator while cranking Yes Check if idle air control valve is OK @F page F-106 o If OK, check air valve page F-105 6 If not OK, replace IAC valve page F-106 No - Yes - No Go to next step Check for correct intake manifold vacuum at idle Go to next step Vacuum: More than 450 mmHg (17.7 inHg} VACUUM GAUGE / Check for air leakage of intake air system components US= page F-1 00 Check if air cleaner element is clean @&Y page F-76 Yes - No Go to next step Replace air cleaner element page F-99 Try known good PCME and check if condition @&Y page F-144 Yes - No - Replace PCME Change fuel to another brand Gartner Banana

TROUBLESHOOTING GUIDE 9 LOW IDLE SPEEDIROUGH IDLE - BEFORE WARM-UP IESCRIPTION I Engine speed low or engine vibrates excessively at idle during warm-up TROUBLESHOOTING HINTS] D Low intake air amount Mass airflow sensor stuck Air cleaner element clogged Idle s~eed control Q Low fuel injection amount Fuel injection control malfunction (Correction for coolant temperature) O Poor atomization of fuel Air valve [Correction for coolant temperature ] iTEP I Low RVP (summer) fuel used in cold weather INSPECTION ACTION - Yes Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 GOG next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) trs page F-81 - - "88"flashes Check PCME terminal 1 E voltage page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME @ page F-143 e If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON ~8 page F-95 SELECT SW A Yes Go to next step Check if PCME terminal voltaaes are OK No - Yes - No - Yes Lamp not ON/OFF with specified switch Check for cause (Refer to specified check sequence) page F-96 Lamp always ON Check wiring between PCME terminal 1 D and Self-Diag- nosis Checker page F-7 Go to next step " (2D, 20 and 2Q) page F-146 Check for cause (Refer to "Check Point for Each Termi- nal") page F-148 Go to next step Check for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg {I?.? inHg) Check for air leakage of intake air system components @ page F-100 INSTALL CLAPS Gartner Banana

TROUBLESHOOTING GUIDE lo 1 LOW IDLE SPEEDIROUGH IDLE - AFTER WARM-UP 3ESCRIPTION I Engine runs normally at idle during warm-up but vibrates excessively after warm-up ;TROUBLESHOOTING HINTS] I> Idle speed control malfunction b AirlFuel mixture too lean Air leakage of intake air system Low fuel line pressure INSPECTION Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON m? page F-79 Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A Disconnect idle air control valve connector at idle and check if engine condition is charged IAC VALVE - Yes No - Yes - No Yes O Air/Fuel mixture too rich Fuel injection control malfunction (Correction for coolant temperature) @ Poor ignition spark Q Low engine compression ACTION Go to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME page F-143 Q If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 Go to next step Lamp not ONIOFF with specified switch Check for cause (Refer to specified check sequence) page F-96 Lamp always ON Check wiring between PCME terminal 1 D and Self-Diag- nosis Checker page F-7 Go to next step Check idle air control valve page F-106 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION >heck if throttle valve is closed throttle position Yes when accelerator released I 11 :heck if "00" is displayed on Self-Diagnosis Check- Yes w with ignition switch ON @? page F-79 HIGH IDLE SPEED - AFTER WARM-UP SELECT SW A SYSTEM SELECT 1 FROUBLESHOOTING HINTS] Excessive intake air supplied to engine O Throttle valve not fully closed @ ldle speed control malfunction Air valve not closing ldle air control valve stuck Incorrect coolant temperature signal STEP 1 >heck switches for correct operation with Self- I Yes liagnosis Checker Monitor Lamp and ignition ;witch ON page F-95 SELECT SW A ACTION Go to next step Check if throttle linkage is correctly installed and operates freely @? page F-103 o If OK, go to next step o If not OK, clean, adjust or replace linkage Daae 6103 Go to next step - Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) @? page F-81 "88" flashes Check PCME terminal 1 E voltage @S page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME E=T page F-143 o If not OK, check wiring between PCME and Self-Diagno- sis Checker @? page F-7 Go to next step Lamp not ONlOFF with specified switch Check for cause (Refer to specified check sequence) E=T page F-96 am^ always ON Check wiring between PCME terminal ID and Self-Diag- IOS~S Checker @? page F-7 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