Engine Controls - Basic Testing: Other Mazda MX-5 NA

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.

COMPRESSION SPECIFICATIONS

Exhaust System Backpressure

The exhaust system can be checked with a vacuum or pressure gauge. Remove O2 sensor or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge and run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi (.12-.14 kg/cm2), exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction.

FUEL PRESSURE (CARBURETED)

Basic diagnosis of fuel system should begin with determining fuel system pressure.

Note. Fuel pump control unit terminal identification is not available.

Fuel Pump (Electrical)

1. Turn ignition on. Locate fuel control unit under left side of dash. Using a jumper wire, connect terminals "B" to "D". Fuel pump (located in tank) should operate. If pump does not operate, check and replace fuel pump (if necessary). Check fuel pump pressure. See «FUEL PUMP PERFORMANCE (CARBURETED»(ref-18260-S41446236462000123000000) ) table. FUEL PUMP PERFORMANCE Application Pressure: psi (kg/cm2) Min. Volume In 30 Sec. Pts. (L) B2200 Electrical Pump 2.8-3.6 (.20-.25) 1.1 (.53) Mechanical Pump 3.7-4.7 (.26-.33) .9 (.43)
2. If fuel pump operates, remove jumper wire. With ignition on, backprobe rear of fuel pump control unit. There should be 12 volts on terminals "A" and "D" only. If voltage is not as specified, check ignition and power feed.
3. Allow engine to idle. There should be 12 volts on terminals "A", "B", "D" and "F" only. If voltage is missing on terminal "B" only, replace fuel pump control unit. If voltage at any other terminal is not as specified, check ignition coil (tachometer signal) and power feed.

Fuel Pump (Mechanical)

Test pump for pressure and volume. Replace as necessary. See FUEL PUMP PERFORMANCE (CARBURETED) table.

FUEL PRESSURE (FUEL INJECTION)

Fuel Pressure

1. Disconnect circuit opening relay. See CIRCUIT OPENING RELAY LOCATIONS table.
2. To bleed down fuel in system, start engine (if possible) and allow to die. Connect pressure gauge to fuel line at fuel filter. Reconnect circuit opening relay.
3. On Navajo, install EFI Pressure Gauge (T80L-9974-B) to relief valve. Relief valve is located on fuel supply manifold.
4. Turn ignition on. On Miata, MX-3, MX-6, Protege, RX7, 323, 626 and 929, jump test connector terminals Fp and ground. On all other models, use a jumper wire and connect terminals of Yellow fuel pump check connector together. See «FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATION»(ref-18260-S24567345522000123000000) table. On all models, if pump does not run, check fuel pump circuit and circuit opening relay. FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATION Application Location B2200 (PFI) & B2600i On Firewall, Near Windshield Wiper Motor MPV Near Airflow Sensor Navajo At Right Inner Fender Panel
5. If possible, start engine. Check fuel pressure with vacuum connected to and disconnected from pressure regulator. See «REGULATED FUEL PRESSURE (FUEL INJECTION)»(ref-18260-S08791396072000123000000) table. Turn engine off and disconnect jumper wire at fuel pump check connector. Wait 10 minutes and ensure residual pressure is at least 21 psi (1.5 kg/cm2).
6. Operate fuel pump by jumpering fuel pump test connector. Check fuel pump performance. Pinch hose between pressure gauge and fuel filter. DO NOT hold longer than necessary to check pressure. See FUEL PUMP PERFORMANCE table. If pump does not meet specifications, check fuel pump circuits, fuel pump, fuel tank, fuel filter and repair or replace as necessary.

FUEL PUMP PERFORMANCE

REGULATED FUEL PRESSURE (FUEL INJECTION)

Note. Fuel pump control unit terminal identification is not available.

Fuel Pump Circuit (Except Navajo)

1. Turn ignition on. On B2200 (PFI), B2600i and MPV connect terminals of Yellow fuel pump check connector with a jumper wire. See FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATIONS table. On Miata, MX-3, MX-6, Protege, RX7, 323, 626 and 929, attach jumper wire to test connector terminal Fp and to ground in the diagnostic connector, next to battery.
2. Listen for fuel pump operating sound. If there is no sound, check main fuse, circuit operating relay, fuel pump and all electrical connections. On MX-3, MX-6, RX-7, 626 and 929, PCM grounds circuit opening relay and operates fuel pump whenever distributor or crank angle sensor signals are present. On other models, airflow meter grounds circuit opening relay whenever airflow is present.
3. If circuit opening relay does not work, see SYSTEM & COMPONENT TESTING article or appropriate TESTS W/CODES article.

Fuel Pump Circuit (Navajo)

1. If fuel pressure is zero or low, with ignition off, ensure Inertia Fuel Shut-Off (IFS) switch is set. Ensure battery is fully charged. Using a jumper lead, ground FP lead terminal of self-test connector. (Scheme 2) IFS switch is located under dash to the right of transmission tunnel. With ignition on, engine off and IFS switch electrical connector connected, check voltage at IFS switch. If voltage is 10.5 volts or more at both IFS switch terminals, go to step 3).
2. If voltage is 10.5 volts or more at only one IFS switch terminal, replace IFS switch. If voltage is less than 10.5 volts at both IFS switch terminals, check and repair wiring circuit.
3. With ignition off, ensure connection is okay at pump/sender unit. Turn ignition on, with engine off. Listen for sound of fuel pump operation. If pump is not running, go to next step. If pump is running, check condition of fuel filter. If filter is okay, replace fuel pump. If filter is dirty, replace filter and recheck system.
4. Turn ignition off and disconnect fuel pump/sender connector. (Scheme 2) Turn ignition on, with engine off. Measure voltage at pump power terminal (Pink/Black wire) of pump/sender connector. If voltage is 10.5 volts or more, go to next step. If voltage is not 10.5 volts or more, repair open in Pink/Black wire between fuel pump and inertia switch.
5. With fuel pump/sender connector still disconnected, measure resistance of pump ground wire (Black wire) to chassis ground. (Scheme 2) If resistance is less than one ohm, go to next step. If resistance is not less than one ohm, repair open in Black wire between fuel pump and ground.
6. Turn ignition off. Measure resistance between IFS switch and ground. If resistance is less than 5 ohms, replace fuel pump. For additional circuit testing information see CIRCUIT TEST J in appropriate TESTS W/CODES article.

Scheme 2

Fuel Pump Relay (Navajo)

1. Remove fuel pump relay (located under power distribution box on right inner fender). Connect 12 volts to terminal "C" and ground terminal "D". Check for continuity between terminals "A" and "B". If continuity is present, relay is okay. If continuity is not present, replace relay.
2. Turn ignition on. Ensure 12 volts are present on Red and Black/Yellow or Yellow wires. If 12 volts are not present, repair circuits from Electronic Engine Control (EEC) power relay, battery or power distribution box.
3. Connect 12 volts to terminal "A". Fuel pump should operate. If pump does not operate, repair wiring to inertia switch, fuel pump or fuel pump ground, or replace fuel pump.

Inertia Fuel Shut-Off (IFS) Switch (Navajo)

IFS switch is located under dash to the right of transmission tunnel. To reset switch, make sure no fuel leaks are present. Push reset button.

Circuit Opening Relay (Except MX-3, MX-6, Navajo, 626 & 929)

1. With relay connected, ensure specified voltage is present at relay terminals. See «CIRCUIT OPENING RELAY CIRCUIT VOLTAGE»(ref-18260-S07650052652000123000000) table. For location of circuit opening relays, see CIRCUIT OPENING RELAY LOCATION table.
2. If voltages are okay, remove relay from vehicle. Check relay operation using a 12-volt battery source and perform resistance tests. (Scheme 3)

Circuit Opening Relay (MX-3, MX-6, 626 & 929)

1. With relay connected, ensure battery voltage is present at relay terminal White/Red wire on MX-3, Red/Black wire on MX-6/626 2.0L or Black/White wire on MX-6/626 2.5L and 929. For locations of circuit opening relay, see «CIRCUIT OPENING RELAY LOCATION»(ref-18260-S19873615812000123000000) table.
2. If voltages are okay, remove relay from vehicle. Using a 12-volt battery source, connect 12 volts to relay terminals "A" and "B". Ensure continuity is present across terminals "C" and "D". If continuity is not as specified, replace circuit opening relay.

CIRCUIT OPENING RELAY LOCATION

CIRCUIT OPENING RELAY CIRCUIT VOLTAGE

Scheme 3

SPARK

Check for spark at coil wire and at each spark plug wire using a high output spark tester. Check spark plug wire resistance on suspect wires. Resistance should be no less than 4878 ohms per foot.

IGNITION COIL POWER SOURCE

Turn ignition on. Using voltmeter, check for 12 volts between positive (+) terminal and ground. If no voltage is present, check battery feed, main fuse, EGI main relay (RX7), ignition switch and fusible links.

IGNITION COIL RESISTANCE (EXCEPT MX-3 1.8L, MX-6 & 626)

1. Remove primary and secondary leads from ignition coil. Using ohmmeter, check primary resistance between positive and negative terminals of coil. (Scheme 4) Resistance should be as specified in «IGNITION COIL RESISTANCE»(ref-18260-S29094011102000123000000) table. If resistance is not as specified, replace ignition coil.
2. Check secondary resistance between (positive) terminal and coil tower. (Scheme 4) On leading coil of RX7, check secondary resistance between both high tension towers. On all models, see «IGNITION COIL RESISTANCE»(ref-18260-S29094011102000123000000) table. If resistance is not within specification, replace coil.

IGNITION COIL RESISTANCE (MX-3 1.8L, MX-6 & 626)

1. Remove primary and secondary leads from ignition coil. Using ohmmeter, check primary resistance between terminals "A" and "C" of coil. (Scheme 5) Resistance should be as specified in IGNITION COIL RESISTANCE table. If resistance is not as specified, replace ignition coil.
2. Check secondary resistance between terminal "C" and coil tower. (Scheme 5) See «IGNITION COIL RESISTANCE»(ref-18260-S29094011102000123000000) table. If resistance is not within specification, replace coil.

Scheme 4

Scheme 5

IGNITION COIL RESISTANCE

OPTICAL DISTRIBUTOR VOLTAGE (B2200 PFI, B2600 & MPV 2.6L)

1. Turn ignition on. Check optical distributor ignition source by backprobing distributor terminal for correct voltage. See «OPTICAL DISTRIBUTOR VOLTAGE SPECIFICATIONS»(ref-18260-S33564127522000123000000) table.
2. Ensure ignition coil has battery voltage. If ignition coil resistance and pick-up sensor test okay, check for spark. If spark is still not present, go to appropriate IGNITOR test procedure. If spark is still not present and ignitor is okay, see appropriate SELF-DIAGNOSTICS article.

OPTICAL DISTRIBUTOR VOLTAGE SPECIFICATIONS

DISTRIBUTOR PICK-UP COIL RESISTANCE (B2200 CARBURETED)

1. Disconnect pick-up coil from distributor. Using an ohmmeter, measure resistance between 2 inner terminals on pick-up coil. Replace pick-up coil if resistance is not as specified in «DISTRIBUTOR PICK-UP COIL RESISTANCE (B2200 CARBURETED)»(ref-18260-S34755280532001121700000) table.
2. Ensure ignition coil has battery voltage. If ignition coil resistance and pick-up coil test okay, check for spark. If spark is still not present, go to appropriate IGNITOR test procedure. If spark is still not present and ignitor is okay, see appropriate information TESTS W/CODES article.

DISTRIBUTOR PICK-UP COIL RESISTANCE (B2200 CARBURETED)

DISTRIBUTOR PICK-UP COIL RESISTANCE (MPV 3.0L)

1. Disconnect pick-up coil from distributor. Using an ohmmeter, measure resistance between terminals on pick-up coil. (Scheme 6) Replace pick-up coil if resistance is not as specified in «DISTRIBUTOR PICK-UP COIL RESISTANCE (MPV)»(ref-18260-S37990390602001121700000) table.
2. Ensure ignition coil has battery voltage. If ignition coil resistance and pick-up coil test okay, check for spark. If spark is still not present, go to appropriate IGNITOR test procedure. If spark is still not present and ignitor is okay, see appropriate information TESTS W/CODES article.

DISTRIBUTOR PICK-UP COIL RESISTANCE (MPV)

Scheme 6

CRANK ANGLE SENSOR RESISTANCE (MX-3 1.8L, MX-6 & 626 2.5L, RX7 & 929)

1. Disconnect crank angle sensor connector. Crank angle sensor is a separate unit located at front of crankshaft. Measure resistance between terminals. (Scheme 7) If resistance is not as indicated, replace crank angle sensor.
2. If ignition coil resistance and crank angle sensor test okay, check for spark. If spark is still not present, go to HALL-EFFECT SENSORS test procedure.

CRANK ANGLE SENSOR RESISTANCE

Scheme 7

HALL-EFFECT SENSORS (MIATA, MX-3, MX-6, PROTEGE, 323, 626 & 929)

1. Remove distributor. Remove circuit opening relay and disconnect 3-pin connector from distributor. This will prevent coil sparking. Turn ignition on.
2. Using a voltmeter, backprobe power wire and ground wire at distributor. Voltmeter should display 12 volts. If voltage is not as specified, check ignition and ground circuits. Backprobe sensor wire (White wire on MX-3 1.6L or Violet/Green wire on MX-3 1.8L) at distributor. See «HALL-EFFECT SENSOR VOLTAGE SPECIFICATIONS»(ref-18260-S32236988162000123000000) table for other models wire colors. Slowly rotate distributor shaft one turn. Voltmeter should pulse 0-5 volts 4 times (4-cylinder) or 6 times (V6).
3. Backprobe Yellow/Blue wire on MX-3 1.6L or Violet/White wire on MX-3 1.8L at distributor. See «HALL-EFFECT SENSOR VOLTAGE SPECIFICATIONS»(ref-18260-S32236988162000123000000) table for other models wire colors. Slowly rotate distributor shaft one turn. Voltmeter should pulse 0-5 volts one time. If either sensor does not work as described, turn ignition off. Disconnect 4-pin or 6-pin connector at distributor.
4. Turn ignition on. Ensure 5 volts are present at same wires which were checked in steps 2) and 3). If 5 volts are not present, check wiring and PCM. If 5 volts are present, replace distributor assembly.

HALL-EFFECT SENSOR VOLTAGE SPECIFICATIONS

IGNITOR (B2200 W/CARBURETOR, MX-3 1.8L, MX-6 & 626)

Testing information is not available. If coil, PCM, sensor and wiring are okay, replace ignitor.

IGNITOR (B2200 W/PFI, B2600I, MIATA, MX-3 1.6L, PROTEGE, 323 & 929)

1. Ensure coil and power source are okay before checking ignitor. Disconnect coil ignitor connector. Install Ignitor Checker (49 F018 002) and Adapter Harness (49 N018 011 on MX-3 1.6L, Protege and 323; 49 N018 001 on all others). Connect the ignitor checker and adapter between the ignitor and wiring harness, connect the power leads to the battery.
2. Turn ignition on. Disconnect the high-tension coil lead from the distributor and hold it about 1/4" from ground. Flip the SW2 on and off, and verify a strong Blue spark is discharged from lead. If spark is weak in color, replace the coil. If no spark is present, check battery feed, main fuse, ignition switch and fusible links. Repair or replace as necessary. CAUTION: DO NOT hold the SW2 switch on longer than one second.
3. Turn ignition on. Using voltmeter, check voltage on Black wire of adapter harness. Flip SW2 switch on and off. Verify voltmeter fluctuates. If voltmeter does not fluctuate, replace ignitor and retest.

IGNITOR (MPV & 929)

1. Turn ignition off. Disconnect ignitor connector and install Test Harness (49 H018 001 on MPV or 49 N018 001 on 929). Using a needle-type ohmmeter, connect (+) lead to ground and (-) lead to single-pin test wire of test harness. (Scheme 8) CAUTION: Ensure ohmmeter is installed with (+) lead to ground and (-) lead to single-pin wire of test harness. DO NOT reverse leads or damage may result.
2. Connect Ignitor Checker (49 F018 002 on MPV or 49 H018 910 on 929) to other lead of test harness and to battery. Set ohmmeter to X1 scale.
3. Turn ignition on. DO NOT touch ignitor checker SW1 switch. Push up ignitor checker SW2 switch and note ohmmeter reading. Ohmmeter needle should jump to 1/2 of the scale and then return. If ohmmeter does not operate as specified, replace ignitor.

Scheme 8

IGNITOR (RX7)

1. Turn ignition off. Disconnect ignitor connector and install Test Harness (49 F018 003). Using a needle-type voltmeter, connect (+) lead to ground and (-) lead to Black test wire of test harness. CAUTION: Ensure voltmeter is installed with (+) lead to ground and (-) lead to single-pin wire of test harness. DO NOT reverse leads or damage may result.
2. Connect Ignitor Checker (49 F018 002) to large lead of test harness and to battery. Turn ignition on. Ignitor checker SW1 switch may be in any position.
3. Ensure voltmeter displays 12 volts. Push up ignitor checker SW2 switch and note voltmeter reading. Voltmeter needle should jump or wiggle. Release SW2 switch. If voltmeter does not operate as specified, replace ignitor.
4. Repeat steps 1)-3) for Brown test wire and Gray test wire. If ignitor does not cause voltmeter needle to respond, replace ignitor.

IGNITION CHECKS (NAVAJO)

Note. While performing diagnostics, DO NOT connect Powertrain Control Module (PCM) to breakout box unless directed to do so.

Note. Perform following tests in sequence shown, unless test procedures indicate otherwise. For the following test, Electronic Distributorless Ignition System (EDIS) or Ignition Control Module (ICM) may be used to describe the ignition system.

Note. California models are equipped with a Camshaft Position Sensor (CMP). This sensor uses a Hall Effect switch and is located at top rear of engine. For testing information, see TESTS W/CODES article.

ISOLATE ICM/PIP FAULT

With key off, disconnect PCM. Connect LED test light leads between breakout box pins No. J43 (PIP E) and J7 (ground). Crank engine. If LED test light blinks, replace PCM. If test light does not blink, check PIP for short to ground or power. Repair any problems found. If no problems are found, replace ICM.

CHECKING PLUGS & WIRES

Crank engine. Using a high-output spark tester, check for spark at both spark plug wires of each coil. If there is no spark at all coils, go to CHECK FOR VBAT TO ICM. If spark is missing from both spark plug wires of one or 2 coils, go to CHECK VBAT FOR OPEN TO COIL. If spark is missing from one wire, replace spark plug wire and spark plug. Recheck ignition system.

CHECK FOR VBAT TO ICM

Turn key off and disconnect PCM. Set DVOM to 20-volt scale. Turn ignition on. Measure voltage between breakout box pins No. (+) J51 (VBAT E) and (-) J7 (BAT negative). (Scheme 9) If voltage is greater than 10.5 volts, go to CHECK FOR GROUND OPEN TO ICM. If voltage is 10.5 volts or less, repair open or short in circuit from ignition switch.

CHECK FOR GROUND OPEN TO ICM

Turn key off and disconnect PCM. Measure resistance between breakout box pins J27 (PWR GND E) and chassis ground. If resistance is less than 5 ohms, go to CHECK VRS RESISTANCE. If resistance is 5 ohms or more, repair open in ground circuit.

CHECK VRS RESISTANCE

Turn key off and disconnect PCM. Connect negative lead of ICM diagnostic cable to negative battery terminal. Set DVOM to 20-k/ohm scale. Measure resistance between breakout box pins No. J48 (VRS

(Scheme 9) If resistance is 2580-2700 ohms, go to VRS SENSOR. If resistance is not 2580-2700 ohms, repair wires between VRS and ICM or replace VRS.

Scheme 9

VRS SENSOR

Ensure trigger wheel on crank pulley and VRS are not damaged. Ensure VRS is not touching trigger wheel. If no problems are found, disconnect ICM connector. Crank engine and check for slight A/C voltage at ICM harness terminals No. 5 and 6. (Scheme 9) If A/C voltage is not pulsing greater than one volt, check VRS circuits for opens or shorts. If no problems are found, replace VRS sensor. If A/C voltage pulses greater than one volt, go to CHECK VBAT OPEN TO COIL.

CHECK VBAT FOR OPEN TO COIL

Turn key off and disconnect harness at coil pack. Turn key on. Measure voltage between coil pack harness terminal No. 4 and ground. If more than 10.5 volts are present, go to next step. If there is less than 10.5 volts, repair open circuit. Remove all test equipment and reconnect all components. Clear Continuous Memory and check for fault codes.

CHECK C1, C2 & C3 AT COIL PACK (CRANKING)

Turn key off. Reconnect harness at coil pack. Set DVOM on 20-volt AC scale. While cranking engine, backprobe between coil terminals No. 1, 2 and 3, and chassis ground. (Scheme 9) If any voltage reading while cranking is NOT 0.2-1.0 volt, go to CHECKING ICM CONTROL. If all voltage readings while cranking are 0.2-1.0 volt, go to CHECKING COIL PACK.

CHECK C1, C2 & C3 AT COIL PACK (RUNNING)

Turn key off. Reconnect harness at coil pack. Set DVOM on 20-volt AC scale. Start engine, backprobe between coil terminals No. 1, 2 and 3, and chassis ground. (Scheme 9) If any voltage reading while running is NOT 1.0-2.0 volts, go to CHECKING ICM CONTROL. If voltage reading of each coil (while running) is 1.0-2.0 volts, go to CHECKING COIL PACK.

CHECKING COIL PACK

Turn key off, and disconnect coil pack. Measure resistance between coil pack terminal No. 4 and all other terminals. (Scheme 9) If each resistance is greater than 0.8 ohm, replace coil pack. If any resistance is less than 0.5 ohm, replace coil pack and ICM. Remove all test equipment, and reconnect all components. Clear Continuous Memory and check for fault codes.

CHECKING ICM CONTROL

If voltage was less than described in CHECK C1, C2 & C3 AT COIL PACK (RUNNING) or CHECK C1, C2 & C3 AT COIL PACK (CRANKING), replace coil pack. If voltage was greater than described, check circuits between coil pack and ICM module for opens or shorts. If circuits okay, replace ICM. Remove all test equipment, and reconnect all components. Clear Continuous Memory, and check for fault codes.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and base ignition timing are set to specification. If necessary, see ADJUSTMENTS article.

IGNITION TIMING SPECIFICATIONS

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to appropriate TESTS W/CODES article. If no hard codes are found in self-diagnostics, proceed to appropriate TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.