1994 MAZDA MX-5 air condition

TROUBLESHOOTING GUIDE INSPECTION ACTION Check if PCME terminal voltages are OK (1 R, 1 T, ZD, 20 and 20) us page F-146 Yes Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") Djp paae F-148 Check if strong blue spark is visible at each discon. nected high-tension lead while cranking engine Yes - No Go to next step Check ignition system (Refer to Troubleshooting "Misfire") Section G Check for EGR system malfunction page F-124 Yes - No Repair or replace Go to next step Check for fuel injector operating sound at each in- Yes Go to Step 10 jector at idle No - Yes Go to Step 9 Check if battery positive voltage exists at fuel injec- tor connector B terminal with ignition switch ON Check if fuel injector resistance is OK page F-119 Resistance: 12-1 6R G If OK, check wiring between injector and PCME page F-7 o If not OK, replace injector L@? page F-119 No - Yes Check wiring between main relay and fuel injector page F-7 Go to next step Check for correct engine compression Section B Engine compression: 1,255-883 kPa I12.8-9.0 kgflcm2, 182-1 28 psi)-300 rpm Check engine condition Section B I Worn piston, piston rings or cylinder wall r Defective cylinder head gasket r Distorted cylinder head r Improper valve seating Valve sticking in guide No - Yes :heck if spark plugs PLUG GAP 1 .O-1 .l mm (0.04+0.043 in} DETERIORATION 30 to next step qepair, clean, or replace Section G Try known good PCME and check if condition im- roves @r page F-144 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

F TROUBLESHOOTING GUIDE [TROUBLESHOOTING HINTS] D AirIFuel mixture too rich 7 Q Vaoor lock CRANKS NORMALLY BUT HARD TO START - AFTER WARM-UP Fuel pressure not held in fuel line after engine stops 0 High RVP (winter) fuel used in warm weather ACTION DESCR'PnON Fuel injection control malfunction Fuel injector fuel leakage Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON uar page F-79 Engine cranks at normal speed but requires excessive cranking time (more than 5 sec.) before starting after run- ning and hot soaked Battery in normal condition Engine starts normally when cold 1 Check if PCME terminal voltages are OK (2D,2R and 2Q) page F-145 INSPECTION Run engine at idle and check if fuel line pressure is held after ignition switch turned OFF page F-109 Fuel line pressure: More than 147 kPa (1.5 kgf/cm2, 21 psi} for 5 min. INSTALL CLAPS Try known good PCME and check if condition im- proves US page F-144 Yes - No Yes - No Yes No - Yes 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 @sf page F-143 G 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 Termi- nal") page F-148 Go to next step Block outlet of pressure regulator and check if fuel line pressure is held after ignition switch is turned OFF page F-117 If OK, replace pressure regulator page F-118 Q If not OK, check fuel pump hold pressure I@? page F-115 If fuel pump is OK, check fuel injector for fuel leakage page F-120 Replace PCME Change fuel to another brand Gartner Banana

TROUBLESHOOTING GUIDE B ROUGH IDLE - ALWAYS JCRIPTION I Engine vibrates excessively at idle in every condition 'ROUBLESHOOTING HINTS] AirIFuel mixture too lean Air leakage Fuel injection control malfunction Low fuel line pressure Q One or more injectors not operating or clogged O One or more spark plugs not sparking @ Injection timing misadjustment O Low engine compression INSPECTION >heck for correct intake manifold vacuum at idle tacuum: More than 450 mmHg f17.7 inHg} VACUUM GAUGE =heck if air cleaner element is clean page F-76 :heck if "00" is displayed on Self-Diagnosis Check- 3r with ignition switch ON page F-79 SELECTSWA SYSTEM SELECT 1 Sheck switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON SELECT SW A page F-95 Sheck if PCME terminal voltages are OK MONITOR . Sheck i (1 R, IT, 2D, 20 and 2Q) page F-146 - Yes Yes - No - Yes Yes - No - Yes ACTION 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 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-136 Specification: Battery positive voltage (Ignition switch ON) e 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 ONlOFF 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 as? page F-7 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") us ~aae F-148 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Check for fuel injector operating sound at idle with sound scope or screwdriver Check if battery positive voltage exists at fuel injec- tor connector 6 terminal Disconnect each high-tension lead at idle and check if engine speed decreases equally each time - - - Check if spark plu CARBON BUILDUP PLUG GAP 1.0-1 .l mm (0.040-0.043 in) DAMAGE AND DETERIORATION Check for correct ignition timing at idle page F-76 Ignition timing: 10" +. lo BTDC Check for EGR system malfunction w page F-124 Check for correct fuel line pressure at idle * page F-110 Fuel line pressure: 26-14 kPa f2.7-3.2 kgflcm2, 38-46 psi} (Vacuum hose to pressure reaulator discon- - Yes - No - Yes No - Yes - No - Yes - No Yes No - Yes ACTION Yes - No - Go to Step 8 Go to Step 7 Check if fuel injector resistance is OK page F-119 Resistance: 12-1 632 0 If OK, check wiring between PCME and fuel injector @r page F-7 Q If not OK, replace fuel injector page F-119 Check wiring between PCME and fuel injector page F-7 Disconnect each fuel injector connector at idle and check if engine speed decreases equally each time 0 If OK, go to Step 10 o If not OK, check fuel injector for fuel leakage G= pane F-120 Go to step 9 Check for correct engine compression t@ Section B Q if OK, replace fuel injector t@ page F-119 o If not OK, check for cause (Refer to Section 6) U=S Section B Repair, clean, or replace Section G Check for correct idle speed @ page F-77 Idle speed: 850 -c 50 rpm (MT) 800 2 50 rpm (AT) 0 If OK, go to next step 0 If not OK, adjust idle speed w page F-77 Adjust page F-72 Repair or replace Go to next step Go to next step Low pressure Check fuel line pressure while pinching fuel return hose 3 If fuel line pressure quickly increases, check pressure regulator US= page F-118 3 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure E+T page F-115 Try known good PCME and check if condition im- proves w Daae F-144 Gartner Banana

F TROUBLESHOOTING GUIDE STEP 5 INSPECTION Check if air cleaner element is clean page F-76 Connect System Selector to data link connector and set Test Switch to "SELF TEST" when engine is cold Check if engine speed decreases as engine warms UD -r tw page F-101 , GND TEN With condition of Step 5 check for correct ignition timing at idle after warm-up G-X page F-76 Ignition timing: 10" + 1" BTDC Try known good PCME and check if condition im- 3roves @S page F-144 - Yes Yes - No - Yes Yes ACTION Go to next step Replace air cleaner element tw page F-99 Go to next step Check air valve @ page F-105 Go to next step Adjust @ page F-76 Replace PCME page F-143 Change fuelto another brand 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

F TROUBLESHOOTING GUIDE INSPECTION :heck for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg I17.7 inHg) VACUUM GAUGE :heck if PCME terminal voltages are OK (2D, 20 and 2Q) page F-146 :heck for correct ignition timing at idle @S page F-76 Ignition timing: 10" + 1" BTDC :heck for correct fuel line pressure at idle @S page F-11 0 Fuel line pressure: 265--314 kPa f2.7-3.2 kgf/cm2,38-46 psi} (Vacuum hose to pressure regulator discon- INSTALL CLAPS ' :heck if strong blue spark is visible at each discon- iected high-tension lead while cranking engine - -- :heck for correct engine compression @S Section B Engine compression: 1,255-883 kPa (12.8-9.0 kgf/cm2, 182-128 psi)-300 rpm - Yes Yes Yes No - Yes - No - Yes No - Yes - No - ACTION Go to next step Low vacuum Check for air leakage of intake air system components page F-100 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") page F148 Check for correct idle speed page F77 Idle speed: 850 -c 50 rpm (Mi) 800 + 50 rpm (AT) e If OK, go to next step o If not OK, adjust idle speed page F-77 Adjust page F-76 Go to next step Low pressure Check fuel line pressure while pinching fuel return hose 0 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 Go to next step Check ignition system (Refer to Troubleshooting "Misfire") Section G Go to next step Check engine condition Section B Worn piston, piston rings or cylinder wall Defective cylinder head gasket Distorted cylinder head Improper valve seating Valve sticking in guide Gartner Banana