1994 MAZDA MX-5 Workshop Manual

TROUBLESHOOTING GUIDE INSPECTION Check for correct fuel line pressure at idle Section B ACTION Go to next step - Yes High compression Check engine condition Carbon deposits Engine compression: 1,255-883 kPa 112.8-9.0 kgf/cm2, 182-128 psi)-300 rpm Section B Check for correct fuel line pressure at idle page F-110 Yes - No Check if fuel line pressure decreases when accelerating quickly Fuel line pressure: 265-314 kPa (2.7-43.2 kgf/cm2, 38-46 psi) (Vacuum hose to pressure regulator discon- nected) 0 If decreases, check for clogging between fuel pump and pressure regulator 0 If no decrease, 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 w page F-115 INSTALL CLAPS Check for correct ignition timing at idle IJ&T page F-76 Yes Check if ignition timing advances when accelerating o If advances, go to next step o If no advance, replace PCME LW page F-143 Ignition timing: 10" + lo BTDC No - Yes Adjust page F-76 Check for EGR system malfunction page F-124 Repair or replace Go to next step Go to next step Check if cooling system is OK Section E Yes No - Yes Repair or replace Thermostat Electric cooling fan Radiator ~3 Section E Section B Section E Try known good PCME and check if condition im- proves IJ&T page F-144 Replace PCME page F-143 Change fuel to another brand or use higher octane fuel Gartner Banana

TROUBLESHOOTING GUIDE rROUBLESHOOTlNG HINTS] > Poor connection or damaged fuel system or fuel evaporative system 3 Charcoal canister overflow due to fuel evaporative system malfunction 28 INSPECTION Check if fuel leak or damage are visible at fuel sys- tem and fuel evaporative system FUEL ODOR ACTION IESCRIPTION I Gasoline odor in cabin Yes Repair or replace page F-107 30 to next step Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON page F-79 SELECT SW A SYSTEM SELECT 1 I Yes - No - Yes So 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) o 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 vacuum is felt at purge solenoid valve with engine running and throttle valve opened (Neutral switch connector disconnected) Go to Step 5 Check for purge solenoid valve operating sound in this condition o If OK, check vacuum hoses for clogging page F-6 o If not OK, go to next step Apply battery positive voltage and ground to purge solenoid valve and check if air flows through valve Yes Check PCME terminal 2X voltage page F-146 Replace purge solenoid valve @S page F-132 Try known good PCME Daae F-144 Gartner Banana

F TROUBLESHOOTING GUIDE I [TROUBLESHOOTING HINTS] Hinh sulfur content fuel used 29 ISTEP l INSPECTION I ACTION I EXHAUST SULFUR SMELL I 1 I Chanae fuel to another brand I DESCRIPTION I Exhaust gas smells abnormal (Rotten egg smell) 30 I HIGH OIL CONSUMPTION TROUBLESHOOTING HINTS] D PCV system malfunction ne malfunction (Oil working up, working down, or leakage) INSPECTION Check if PCV hose, ventilation hose or their attach- ing nipples are separated, damaged, clogged, or restricted L@? page F-130 Check if air pressure or oil is present at ventilation hose VENTILATION Check if vacuum is felt at PCV valve at idle page F-130 Yes - No - Yes No - Yes ACTION Repair or replace e page F-122 Go to next step Go to next step Check engine condition Oil leakage Worn valve seal Worn valve stem Worn valve guide Section B Check engine condition Section B Worn piston ring groove Stuck piston ring Worn piston or cylinder Replace PCV valve page F-130 Gartner Banana

TROUBLESHOOTING GUIDE F POOR FUEL ECONOMY I [TROUBLESHOOTING HINTS] Nhile fuel consumption is drastically increased during city driving, short-run operation, stop and go driving, extended winterwarm- ~p periods, etc., as opposed to "trip" mileage, an attempt should be made to determine these factors when confronted with "poor mileage" conditions. However, since the operator is not always at fault, the following is offered. 3 Operator depressing accelerator more than usual due to O Alcohol blended fuel used low engine power @ High vehicle load Poor ignition Low tire pressure Low intake air amount Unrecommended tire used Electric spark advance control malfunction Brake dragging Clutch slipping @ Fuel cut control malfunction Exhaust component restricted @ High idle speed AirIFuel mixture too rich High fuel line pressure INSPECTION Check factors other than engine Low tire pressure Section Q Unrecommended tire used @zT Section Q Clutch slipping Section H Brake dragging Section P Exhaust component restricted @zT page F-128 ACTION - Yes Go to next step Repair Check if air hoses are connected correctly @zT page F-99 Yes - No Go to next step Repair @zT page F-99 Check if air cleaner element is clean page F-76 Yes - No Go to next step Replace page 699 Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON @zT page F-79 Yes Go to next step SELECT SW A SYSTEM SELECT 1 Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) page F-81 "88" flashes Check PCME terminal 1 E voltage US page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME page F-143 6 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 page F-95 SELECT SW A Yes Go to next step ~~p Lamp not ONIOFF with specified switch Check for cause (Refer to specified check sequence) @zT page F-96 Lamp always ON Check wiring between PCME terminal 1 F and Self-Diag- nosis Checker us page F-7 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Check if PCME terminal voltages are OK (20,2N, 20,2P, 2Q, 2R, 2U and 2V) page F-146 Check if fuel cut operation is OK during decelera- tion Fuel cut: Above 1,900 rpm after warm-up Check for correct ignition timing at idle page F-76 Ignition timing: 10" 2 lo BTDC Check for correct fuel line pressure at idle page 6118 Fuel line pressure: 216-264 kPa i2.2-2.7 kgf/cm2, 32-48 psi) INSTALL CLAPS ' 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 {I .5 kgf/cm2, 21 psi) for 5 mln. PRESSURE IGNITION 5 MIN. TIME SWITCH OFF Yes - No Yes No Yes No Yes No - Yes No ACTION Go to next step Check for cause (Refer to "Check Point for Each Terrni- nal") paae F-148 Go to next step Try known good PCME @ page F-144 Go to next step Adjust page M6 Go to next step High pressure Check if vacuum hose to pressure regulator is damaged or poorly connected o If OK, replace pressure regulator * page F-119 O If not OK, repair or replace hose So to next step Check fuel injector for fuel leakage page F-120 Change fuel to another brand Gartner Banana

TROUBLESHOOTING GUIDE IT- MIL ALWAYS ON I ( DESCRIPTION I Self-Diagnosis Checker does not indicate Diagnostic Trouble Code No. but MIL always ON I I - - [TROUBLESHOOTING HINTS] Short circuit in wiring harness PCME malfunction ISTEP l INSPECTION I ACTION I 1 STEP 33 Disconnect (1 E) wire from PCME and check if MIL goes off 1 E MIL NEVER ON Ground (1 E) wire at PCME with jumper wire and check if MIL comes on 1 E Self-Diagnosis Checker indicates Diagnostic Trouble Code No. of input device but MIL never ON DEscR~pT~O~ I : Other indicator and warning lamps OK [TROUBLESHOOTING HINTS] Bulb burned out Open circuit in wiring harness PCME malfunction INSPECTION Yes No ACTION c3 If OK, replace PCME page F-143 I Q If not OK, repair PCME connector Replace PCME page F-143 Check for short circuit in wiring between combination me- ter and PCME page F-7 Yes No Check if bulb is OK I I Check connection condition of PCME connector tw page F-144 I r> If OK, repair (1 E) wire between PCME and combination meter as= page F-7 c3 If not OK, replace bulb Section T Gartner Banana

F TROUBLESHOOTING GUIDE DESCRIPTION I Blower fan operates but cool air not expelled ITROUBLESHOOTING HINTS] Open or short circuit in wiring harness NC relay malfunction 34 Air conditioning sensor malfunction Magnetic clutch malfunction PCME malfunction AIC DOES NOT WORK INSPECTION ;round terminal B at NC relay with jumper wire Yes tnd check if condenser fan operates when ignition ;witch is turned ON #C RELAY I ;round terminal B at PCME 1 J terminal with jump- Yes ,r wire and check if condenser fan operates when gnition switch is turned ON - No :heck if Air conditioning sensor is OK Yes Section U ACTION 30 to next step 30 to A/C system Troubleshooting Section U 30 to next step qepair wire between PCME and A/C relay page F-7 Try known good PCME page F-144 ;heck Air conditioning sensor and wiring Section U Gartner Banana

ENGINE TUNE-UP ENGINE TUNE-UP PREPARATION L" SST r I I 16EOF2-012 BASIC INSPECTION Engine Oil 1. Remove the dipstick and check the engine oil level and condition. 2. Add or change oil as necessary. 49 B019 9AO System Selector Coolant (engine cold) For inspection of ignition timing and idle speed Warning Removing the radiator cap or the coolant drain plug while the engine is running, or when the en- gine and radiator are hot is dangerous. Scalding coolant and steam may shoot out and cause seri- ous injury. It may also damage the engine and cooling system. Turn off the engine and wait until it is cool. Even then, be very careful when remov- ing the cap. Wrap a thick cloth around it and slow- ly turn it counterclockwise to the first stop. Step back while the pressure escapes. When you're sure all the pressure is gone, press down on the cap-still using a cloth-turn it, and remove it. 1. Verify that the coolant level is near the radiator filler neck. 2. Verify that the coolant level on the coolant dipstick is be- tween the F and L marks. 3. Add coolant if necessary. Battery Removing the label on the top of the battery or removing the vent caps will void the battery's warranty. 1. Clean any corrosion on the clamps or battery posts. 2. Verify that the battery top is clean. If necessary, clean with baking soda and water. 3. Verify that cables are in good condition and not frayed or corroded. Repair or replace if necessary. 4. Verify that cable clamps are tight. Note Because this is a maintenance free battery, it is not necessary to check the fluid level. Gartner Banana