Compression MAZDA MX-5 1994 User Guide

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

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

TROUBLESHOOTING GUIDE INSPECTION Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 14 - -- Check for correct idle speed page F-77 IDLE MOVES UP AND DOWN Idle speed: 850 2 50 rpm (MT) 800 + 50 rpm (AT) GND TEN I DESCRIPTION I Engine speeds up and down periodically at idle [TROUBLESHOOTING HINTS] O Fuel cut occurs at idle O Air leakage of intake air system Air valve not closing after warm-up and idle speed @ Poor ignition spark reaches to fuel cut speed 8 AirIFuel mixture too rich Q Fuel injection amount fluctuating Fuel evaporative system malfunction Bad contact point inside mass airflow sensor 8 Low engine compression 5'=€% CONNECT TERMINAL AIR ADJUSTING SCREW Check for correct ignition timing at idle * page F-76 Ignition timing: 10" 2 lo BTDC - Yes - No - Yes - No Yes ACTION Go to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) @r page F-81 "88" flashes Check PCME terminal 1 E voltage re page F-145 Specification: Battery positive voltage (Ignition switch ON) 3 If OK, replace PCME page 6143 3 If not OK, check wiring between PCME and Self-Diagno- sis Checker page F-7 So to next step 2heck if idle speed can be adjusted by turning air adjust ;crew 3 If OK, adjust idle speed 3 If not OK, check air valve page F-105 20 to next step idjust I@= page F-76 Gartner Banana

TROUBLESHOOTING GUIDE - TEP - 4 INSPECTION ACTION ;heck for correct intake manifold vacuum at idle Yes - No - Yes Go to next step Intake manifold vacuum: More than 450 mmHg I17.7 InHg} ,VACUUM GAUGE Low vacuum Check for air leakage of intake air system page F-100 Zheck for fuel injector operating sound at idle with sound scope or screwdriver Go to Step 7 Go to Step 6 Check if fuel injector resistance is OK us page F-119 Check if battery positive voltage exists at fuel injec- tor connector B terminal Yes - No - Yes - No Resistance: 12-1 6R e If OK, check wiring between PCME and fuel injector page F-7 Q If not OK, replace fuel injector us 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 Disconnect each high-tension lead at idle and :heck if engine speed decreases equally each time Q If OK, go to Step 9 Q If not OK, check fuel injector for fuel leakage page F-120 Go to step 8 Zheck if spark plugs are OK ILDUP PLUG GAP 1.0-l.lmrn [0.04-.043 in) DAMAGE AND DETERIORATION Check if PCME terminal voltages are OK (1 R, IT, 2Q2Q and 2X) page F-146 Yes - No - Yes Check for correct engine compression Section B + If OK, replace fuel injector page F-119 Q If not OK, check for cause (Refer to Section 6) Section B Repair, clean, or replace Go to next step No - Yes Check for cause (Refer to "Check Point for Each Termi- nal") page F-148 Check purge solenoid valve = page F-132 - - Check if vacuum is felt at purge solenoid valveat Go to next step Try known good PCME and check if condition im- proves page F-144 Gartner Banana

TROUBLESHOOTING GUIDE F INSPECTION Check for correct engine compression Section B Engine compression: 1,255-863 kPa {I 2.8-9.0 kgf/cm2, 182-1 28 psiwOO rpm Try known good PCME and check if condition im- Droves ACTION 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 af page F-144 35UOFX-024 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 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