air condition MAZDA MX-5 1994 Owner's Guide

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 :heck if spark plugs are OK WEAR AND CARBQN BUILDUP BURNS PLUG GAP 1 .O-1 .l mm DAMAGE AND t0.040--0.043 in) DETERIORATION DAMAGE Try known good PCME and check if condition im- proves as page F-144 Yes ACTION Go to next step Repair, clean, or replace Section G Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Zonnect System Selector to data link connector and set Test Switch to 'SELF TEST" when engine s cold :heck if engine speed decreases as engine warms - T SW. Disconnect idle air control valve connector at idle and check if engine condition is changed IAC VALYE CONNECTOR Pinch PCV hose with pliers and check if engine speed decreases Check if PCME terminal voltages are OK [I R, 2D, 20 and 2Q) page 6146 Yes No - Yes - No - Yes - No - Yes - No ACTION 30 to next step :heck air valve w page -05 30 to next step Check idle air control valve page F-106 Check PCV valve page F-130 30 to next step Try known good PCME page F-144 Check for cause (Refer to "Check Point for Each Termi- ial") page F-148 35UOFX-Oli Gartner Banana

TROUBLESHOOTING GUIDE ldle speed control malfunction Engine speed feedback control malfunction ldle air control valve stuck 12 INSPECTION LOW IDLE SPEED - WHEN AIC, PIS, OR EIL ON Check if "00" is displayed on Self-Diagnosis Check- er with ignition switch ON @? page F-79 SELECT SWA SYSTEM SELECT 1 I Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON page F-95 SELECT SW A DESCRIPTIOH MONITOR [LAMP &\L SYSTEM SELECT 1 : Engine speed decreases at idle when NC, PIS, or EIL ON NC, PIS, headlights, blower fan and electric coolant fan operate normally Check if continuity exists between data link con- nector terminal TEN and ground --., rrROUBLESHOOTlNG HINTS] Disconnect idle air control valve connector at idle and check if engine condition is changed IAC VALYE CONNECTOR /' Yes - No Yes Yes No - Yes - No - ACTION Go to next step Diagnostic Trouble Code No. displayed Check for cause (Refer to specified check sequence) US= 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 G 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) as page F-96 Lamp always ON Check wiring between PCME terminal I D and Self-Diag- nosis Checker @T page F-7 Check for short circuit in wiring between data link connec- tor terminal TEN and ground as page F-7 Go to next step Try known good PCME page F-144 Check idle air control valve @? page F-106 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 FROUBLESHOOTING HINTS] O Incorrect idle speed ldle speed misadjustment ldle speed control malfunction 15 Q AirIFuel mixture too rich or lean Injector clogged or inoperative Low fuel line pressure ENGINE STALLS AT IDLE - ALWAYS Low intake ai; amount or air leakage Q Poor ianition s~ark DESCRIPTION I Engine starts normally but vibrates excessively and stalls at idle in every condition INSPECTION ;heck for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg f17.7 inHg) VACUUM GAUGE / :heck if air cleaner element is clean @S page F-76 ?heck if "00" is displayed on Self-Diagnosis Check- 3r with ignition switch ON page F-79 SELECT SW A MONITOR . SYSTEM SELECT 1 ;heck switches for correct operation with Self- liagnosis Checker Monitor Lamp and ignition ;witch ON page F-95 SELECT SWA SYSTEM SELECT 1 - Yes - No Yes - No Yes No - Yes - No Go to next step ACTION Check for air leakage of intake air system components * page F-1 00 Go to next step Replace air cleaner element K@- 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 @a page F-145 Specification: Battery positive voltage (Ignition switch ON) 6 If OK, replace PCME @a page F-143 .r, 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 @f page F-7 Gartner Banana

TROUBLESHOOTING GUIDE ACTION So to next step -- INSPECTION - Yes Check if air cleaner element is clean page F-76 Replace air cleaner element page F-99 No Yes - No - Yes - No Disconnect idle air control valve connector when engine is cold and note idle speed Check if engine speed decreases after warm-up Go to next step Check idle air control valve W page F-106 IAC VALYE CONNECTOR Try known good PCME and check if condition im- Replace PCME W page F-143 35UOFX-023 proves - US page F-144 17 ENGINE STALLS AT IDLE - AFTER WARM-UP SCRIPTI ION I Engine runs normally at idle during warm-up but becomes rough and stalls after warm-up TROUBLESHOOTING HINTS] D AirlFuel mixture too lean 0 Low intake air amount 0 Air lcakaae of intake air system Idle speed control malfunction - INSPECTION I ACTION Repair or replace page F-99 ;heck if air is leaked from intake air system com- )orient as page F-100 Yes Go to next step 3isconnect ldle air control valve connector at idle and check if engine condition is cahnged Yes - No Go to next step IAC VALVE CONNECTOR Check idle air control valve page F-106 30 to troubksho%ng No.10 "LOW IDLE SPEED1 ?OUGH IDLE-AFTER WARM-UP" Gartner Banana

TROUBLESHOOTING GUIDE F 18 ENGINE STALLS DURING START-UP DESCRIPTKlN I Engine unexpectedly stops running while starting VROUBLESHOOTING HINTS] @ Misfire occurs when depressing accelerator Q Lack of engine torque for start-up AirIFuel mixture too rich or too lean AirIFuel mixture too rich or too lean Incorrect ignition timing Weak ignition INSPECTION Check if brakes are dragging Section P Check if "00 is displayed on Self-Diagnosis Check- er with ignition switch ON * page F-79 SELECT SW A Check switches for correct operation with Self- Diagnosis Checker Monitor Lamp and ignition switch ON @ page F-95 Disconnect heated oxygen sensor connector and :heck if condition improves SENSOR CONNECTOR -3 I I - Yes - No Yes Yes No - Yes Low intake air amount Low en~ine com~ression ACTION Repair us Section P Go to next step 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 us page F-145 Specification : Battery positive voltage (Ignition switch ON) If OK, replace PCME rc+r page F-143 6 If not OK, check wiring between PCME and Self-Diagno- sis Checker e page F-7 Go to next step Lamp not ONIOFF with specified switch Check for cause (Refer to specified check sequence) uw page F-96 Lamp always ON Check wiring between PCME terminal 1 D and Self-Diag- nosis Checker page F-7 Check heated oxygen sensor @s page F-156 Go to next step Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Disconnect idle air control valve connector at idle and check if engine condition is changed IAC VALVE CONNECTOR . - :heck for correct idle speed page F-77 Idle speed: 850 r 50 rpm (MT) 800 + 50 rpm (AT) GND TEN I CONNECT TERMINAL AIR ADJUSTING SCREW Try known good PCME and check if condition irn- woves Daae F-144 Yes - No - Yes ACTION 30 to next step ;heck idle air control valve page F-106 30 to next step 4djust page M7 Gartner Banana