ignition MAZDA MX-5 1994 Repair Manual

F TROUBLESHOOTING GUIDE INSPECTION ACTION Check if throttle linkage is correctly installed and operates freely Yes Go to next step Correct, clean, or replace as required any binding or dam- aged linkage and adjust cable deflection at throttle body r@ page F-103 Check for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg I17.7 inHg) VACUUM GAUGE / Yes Go to next step No - Yes Check for air leakage of intake air system components r@ page F-100 Go to next step Check if air cleaner element is clean page F-76 Replace air cleaner element page F-99 Check for correct ignition timing at idle page F-76 Yes - No Check if ignition timing advances when accelerating .I, If advances, go to next step o If no advance, replace PCME page F-143 Adjust r@ page M6 Ignition timing: 10" -r- lo BTDC Check for correct fuel line pressure at idle page F-110 Yes Check if fuel line pressure decreases when accelerating quickly Fuel line pressure: 265-314 kPa (2.7-3.2 kgf/cm2, 38-46 psi) (Vacuum hose to pressure regulator discon- nected) o If decreases, check fuel line and filter for clogging 0 If no decrease, go to next step No - Yes Low pressure Check fuel line pressure while pinching fuel return hose 0 If fuel line pressure quickly increases, check pressure regulator page F-113 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 INSTALL CLAPS Repair or replace Check for EGR system malfunction page F-124 No - Yes - No Go to next step - -- Check if exhaust system is restricted page F-128 -- - Repair or replace So to next step Try known good PCME and check if condition im- 3roves page F-144 Gartner Banana

TROUBLESHOOTING GUIDE F 24 Overloaded ) Low intake air amount Throttle valve not oDen fully LACK OF POWER ESCRIPmH - TEP - 1 - 2 : Performance poor under load Reduced maximum speed :heck factors other than engine Clutch slipping as Section H Brake dragging Section P Low tire pressure as Section Q Unrecommended tire size Section Q ;heck if throttle valve wide open throttles when lepressing accelerator fully rROUBLESHOOTlNG HINTS] Factors other than engine malfunction O AirlFuel mixture too lean or too rich Clutch slipping Fuel line pressure low or high Brake dragging Insufficient fuel injection Low tire pressure @ Poor ignition Unrecommended tire size 8 Low engine compression >heck if "00 is displayed on Self-Diagnosis Check- !r with ignition switch ON page F-79 :heck switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON as page F-95 SELECT SW A YSTEM SELECT 1 - Yes Yes Clogged intake air system - INSPECTION I - C 0 0 0 0 - c C - ( E -- I I i I I No - Yes No - Yes - No ACTION %to next step 20 to next step Sheck if accelerator cable is correctly installed page F-103 3 If OK, check throttle body @r page F-101 3 If not OK, install accelerator cable correctly page F-103 - 30 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 @r page F-145 Specification: Battery positive voltage (Ignition switch ON) o If OK, replace PCME page F-143 O If not OK, check wiring between PCME and Self-Diagno- sis Checker E+T 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 @r page F-7 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION :heck for correct ignition timing at idle page F-76 gnition timing: 10" .t lo BTDC ;heck if spark plugs are OK RBON BUILDUP PLUG GAP 1 .O-l.lmrn b.040--0.043 in} DAMAGE AND DETERIORATION DAMAGE :heck if resistance of high-tension leads are OK lesistance: 16 k!2 per 1 m (3.28 ft) :heck if resistance of ignition coil is OK Section G lesistance (at 20°C (66°F)): Secondary coil ... 8.7-12.9 'heck for correct engine compression Section B ngine compression: 1,255483 kPa (12.8-9.0 kgf/cm2, 182-128 psiE.300 rpm Yes No Yes No - Yes Yes No - Yes - No ACTION Check if ignition timing advances when accelerating s, If advances, go to next step +, If no advance, replace PCME terminal voltages page F-143 Adjust page F-76 Go to next step Repair, clean, or replace us Section G Go to next step Replace w Section G Go to next step Replace Section G 30 to next step Zheck engine condition w Section B D Worn piston, piston rings or cylinder wall D Defective cylinder head gasket Distorted cylinder head Improper valve seating B Valve sticking in guide Gartner Banana

TROUBLESHOOTING GUIDE 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 kgflcm2,21 psi) for 5 min. PRESSURE IGNITION 5 MIN. TIME SWITCH OFF Disconnect each fuel injector connector at idle and check if engine speed decreases equally each time Yes - No Yes ACTION High pressure Check if vacuum hose to pressure regulator is damage or poorly connected 6 If OK, replace pressure regulator page F-1 0 If not OK, repair or replace hose Check fuel injector for fuel leakage ~8 page F-1 Go to next step Replace fuel injector a page F: Try known good PCME and check if condition im- mwes page F-144 FEO Gartner Banana

TROUBLESHOOTING GUIDE TROUBLESHOOTING HINTS] D Factors other than engine malfunction Clutch slipping Brake dragging Low tire pressure Unrecommended tire size 25 O AirIFuel mixture too lean or too rich Fuel line pressure low or high Insufficient fuel injection @ Poor ignition 6 Low engine compression POOR ACCELERATION Overloaded D Low intake air amount Throttle valve not open fully Clogged intake air system )ESCRIPTION I Performance poor while accelerating INSPECTION :heck factors other than engine Clutch slipping Section H D Brake dragging Section P t Low tire pressure Section Q D Unrecommended tire size Section Q :heck if throttle valve wide open throttles when jepressing accelerator fully Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A SYSTEM SELECT 1 - Yes - No Yes - No - Yes - No Yes - No ACTION Go to next step Repair Go to next step Check if accelerator cable is correctly installed * page 0 If OK, check throttle body ce Page 0 If not OK, install accelerator cable correctly page Go to next step -- Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequenc US page "88" flashes Check PCME terminal 1 E voltage Us Page Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME * Page 9 If not OK, check wiring between PCME and Self- sis Checker * Page Go to next step Lamp not ONlOFF with specified switch Check for cause (Refer to specified check sequenc * Paw Lamp always ON Check wiring between PCME terminal 1 D and Self nosis Checker * Page ! F-103 ! F-101 I F-103 :e) r F-81 ! F-145 I F-143 Diagno- ! F-7 :e) ! F-96 -Diag- ! F-7 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Check for correct ignition timing at idle t@= page F-76 Ignition timing: 10" +. lo BTDC Check if spark plugs are OK WEAR AND CARBON BUILDUP BURNS PLUG GAP 1 .+I .I mm (0.04C-O.043 in) DAMAGE AND DETERIORATION DAMAGE Check if resistance of high-tension leads are OK Resistance: 16 kR per lm {3.28 ft} Check if resistance of ignition coil is OK Section G Resistance (at 20°C {68"F)): Secondary coil ... 8.7-12.9 kC2 Check for correct engine compression Section 8 Engine compression: 1,255-883 kPa (12.8-9.0 kgf/cm2, 182-128 psi)-300 rpm :heck for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg (17.7 inHg) - Yes - No Yes - No - Yes - No - Yes - No - Yes - No - Yes ACTION Check if ignition timing advances when accelerating o If advances, go to next step o If no advance, replace PCME page F-143 Adjust page F-76 Go to next step Repair, clean, or replace Ojp Section G Go to next step ~eplace as? Section G Go to next step Replace Section G - -- Go to next step :heck engine condition I@= Section B B Worn piston, piston rings or cylinder wall B Defective cylinder head gasket B Distorted cylinder head B Improper valve seating B Valve sticking in guide Check for air leakage of intake air system components as? page F-1 00 Gartner Banana

F TROUBLESHOOTING GUIDE STEP - 17 - 18 - 19 - INSPECTION 3un engine at idle and check if fuel line pressure is ield after ignition switch turned OFF page F-109 %el line pressure: More than 147 kPa {I .5 kgf/cm2, 21 psi) for 5 min. PRESSURE IGNITION 5 MIN. TIME SWITCH OFF - Disconnect each fuel injector connector at idle and :heck if engine speed decreases equally each time FUEL hh INJECTOR CONNECTOR Try known good PCME and check if condition im- proves page F-144 - Yes Yes - No - ACTION High pressure Sheck if vacuum hose to pressure regulator is damaged Dr poorly connected 3 If OK, replace pressure regulator c@= page F-119 3 If not OK, repair or replace hose Check fuel injector for fuel leakage page F-120 Go to next step Replace fuel injector @r page F-119 Gartner Banana

TROUBLESHOOTING GUIDE I IESCRIPTION I Engine runs rough while decelerating and abnormal combustion occurs in exhaust system 26 TROUBLESHOOTING HINTS] 3 AirIFuel mixture too rich Air cleaner element clogged Fuel injection control malfunction (Fuel cut control) Fuel injector fuel leakage 0 Ignition timing misadjustment iTEP I INSPECTION RUNS ROUGH ON DECELERATIONIAFTERBURN ;heck if "00" is displayed on Self-Diagnosis Check- ?r with ignition switch ON page F-79 Sheck switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A SYSTEM SELECT 1 Check for correct ignition timing at idle @= page F-76 lgnition timing: 10" 2 lo BTDC Check if fuel cut operation is OK during decelera- tion Fuel cut: Above 1,900 rpm after warm-up Yes Yes 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 03% page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME IGS page F-143 0 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 G+F page F-7 Go to next step Adjust page F-76 Go to next step Try known good PCME I@= page F-144 Gartner Banana

F TROUBLESHOOTING GUIDE INSPECTION ACTION -- Run engine at idle and check if fuel line pressure is held after ignition switch turned OFF m page F-109 Fuel line pressure: More than 147 kPa {I .5 kgf/cm2, 21 psi) for 5 min. INSTALL CLAPS ' :heck if air cleaner element is clean page F-76 Try known good PCME and check if condition im- )roves US Daae F-144 - Yes I Yes I Go to next step Check fuel injector for fuel leakage page F-120 - Go to next step Replace page F-99 Gartner Banana

TROUBLESHOOTING GUIDE TEP 27 INSPECTION KNOCKING ACTION 30 to next step TROUBLESHOOTING HINTS] > AirIFuel mixture too lean @I Incorrect ignition timing (too advance) Fuel injection amount incorrect Q Overheating Fuel line pressure decreases while accelerating @I Carbon deposits in engine :heck if "00" is displayed on Self-Diagnosis Check- br with ignition switch ON page F-79 Yes Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage uzf page F-145 Specification: Battery positive voltage (Ignition switch ON) 0 If OK, replace PCME page 6143 s If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 >heck switches for correct operation with Self- liagnosis Checker Monitor Lamp and ignition ;witch ON as page F-95 SELECT SW A Yes - No Go to next step Lamp not ONIOFF with specified switch Check for cause (Refer to specified check sequence) page F-96 MONl LAMP II- SYSTEM SELECT 1 Lamp always ON Check wiring between PCME terminal 1 D and Self-Diag- nosis Checker uzf page F-7 Zheck if PCME terminal voltages are OK :1R, IT, 2D, 20, and 2Q) page F-146 Yes Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") uzf page F-148 Sheck for correct intake manifold vacuum at idle Yes - No Go to next step Vacuum: More than 450 mmHg (17.7 InHg) VACUUM GAUGE Check for air leakage of intake air system components as page F-100 Check if air cleaner element is clean page F-76 Yes - No Go to next step Replace air cleaner element page F-99 Gartner Banana