Compression
Warm engine to normal operating temperature before checking the compression. Check engine mechanical condition with a compression gauge, vacuum gauge, or engine analyzer. See engine analyzer manual for specific instructions. See COMPRESSION SPECIFICATIONS table.
| WARNING | DO NOT use ignition switch during compression tests. Use a remote starter to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate the engine's oiling system. |
| Application | Specification |
|---|---|
| Normal Compression Pressure | 185 psi (13.0 kg/cm 2 ) |
| Minimum Compression Pressure | 142 psi (10.0 kg/cm 2 ) |
| Maximum Variation Between Cylinders | 14 psi (1.0 kg/cm 2 ) |
COMPRESSION SPECIFICATIONS
Exhaust System Backpressure
- The exhaust system can be checked with a vacuum or pressure gauge. Remove HO2S sensor or air injection check valve (if equipped).
- Connect a 1-5 psi pressure gauge and operate engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.
- If a vacuum gauge is used, connect vacuum gauge to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold it steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.
FUEL SYSTEM
Basic diagnosis of fuel system should begin by checking fuel pump operation and fuel pressure.
| WARNING | ALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT allow fuel to contact engine or electrical components. |
FUEL PRESSURE
Note. Vehicles use in-tank fuel pump.
- Ensure battery is fully charged and ignition is off. Disconnect negative battery cable.
- Note location for fuel pressure gauge installation. (Scheme 3) Remove necessary components for access to fuel filter. Place container under fuel filter. Cover union bolt with shop towel. Slowly loosen union bolt to release fuel pressure.
- Remove union bolt and gaskets. Install Fuel Pressure Gauge (SST 09268-45012) using NEW gaskets. (Scheme 3) Tighten union bolt to 21 ft. lbs. (29 N.m). Reconnect negative battery cable.
- Install scan tool on data link connector No. 3. see scheme 1 Turn ignition on. DO NOT start engine.
- Turn scan tool on. Select ACTIVE TEST MODE on scan tool. Using scan tool manufacturer's instructions, activate fuel pump and note fuel pressure. Fuel pressure should be within specification. See «FUEL PUMP PERFORMANCE»(ref-22371-S17192080332001010300000) table. NOTE: Fuel pump may also be activated by connecting battery voltage to specified terminals on fuel pump. see scheme 2
- If fuel pressure exceeds specification, replace fuel pressure regulator. Fuel pressure regulator is located on fuel pump assembly in the fuel tank. If fuel pressure is less than specified, check for defective fuel lines, connections, fuel pump, fuel filter or fuel pressure regulator.
- Turn ignition off. Remove scan tool from data link connector No. 3. Start engine and allow engine to idle. Note fuel pressure with engine idling. Fuel pressure should be within specification. See «REGULATED FUEL PRESSURE»(ref-22371-S28506624112001010300000) table.
- Shut engine off and note fuel pressure. Fuel pressure should hold at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes. If fuel pressure does not hold as specified, check for defective fuel pump, fuel injector or fuel pressure regulator.
- Disconnect negative battery cable. Remove fuel pressure gauge. Reinstall union bolt using NEW gaskets. Tighten union bolt to 21 ft. lbs. (29 N.m). Install negative battery cable. Recheck for fuel leaks. Reinstall necessary components.
Scheme 3
Note. For more information on checking fuel injectors and other fuel sub-systems, see SYSTEM/COMPONENT TESTS article.
| Application | Pressure psi (kg/cm 2 ) |
|---|---|
| Paseo | (1) 44-50 (3.1-3.5) |
| (1) Check fuel pressure with engine off and using scan tool connected to data link connector No. 3 with ignition on to activate fuel pump or by connecting battery voltage to terminals on electric fuel pump. | |
| (1) | Check fuel pressure with engine off and using scan tool connected to data link connector No. 3 with ignition on to activate fuel pump or by connecting battery voltage to terminals on electric fuel pump. |
FUEL PUMP PERFORMANCE
| Application Tested | At Idle W/Vacuum psi (kg/cm 2 ) | At Idle W/O Vacuum psi (kg/cm 2 ) |
|---|---|---|
| Paseo | (1) | (1) * |
| (1) Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling. Fuel pressure regulator is not vacuum controlled, as fuel pressure regulator is mounted on in-tank fuel pump. | ||
| (1) | Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling. Fuel pressure regulator is not vacuum controlled, as fuel pressure regulator is mounted on in-tank fuel pump. |
REGULATED FUEL PRESSURE
FUEL PUMP CONTROL CIRCUIT
Note. For information on testing relays and fuel system components, see SYSTEM/COMPONENT TESTS article. Relays may be identified by appropriate illustration in THEORY/OPERATION article. Vehicles are equipped with different combinations of fuel system electrical components. For complete wiring circuit of electrical components on a specific model, see appropriate wiring diagram in WIRING DIAGRAMS article.
Note. EFI main relay may also be referred to as EFI relay.
EFI Main Relay
The EFI fuse supplies constant battery voltage to EFI main relay. When ignition is turned on, voltage is supplied through IGN fuse to EFI main relay. EFI main relay is then energized and provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. The EFI main relay also provides battery voltage to +B terminal of Engine Control Module (ECM) when ignition is turned on.
Circuit Opening Relay
Circuit opening relay controls the fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay. When proper input signals are delivered to the Engine Control Module (ECM), the circuit opening relay ground circuit is grounded at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation.
IGNITION COIL RESISTANCE (DISTRIBUTORLESS IGNITION SYSTEM)
- Remove necessary components and disconnect electrical connector from ignition coil. Disconnect spark plug wire from ignition coil.
- Using ohmmeter, check ignition coil primary resistance between ignition coil positive (+) and negative (-) terminals. These are the terminals that electrical connector was installed on. (Scheme 4) Replace ignition coil if primary resistance is not within specification. See «DISTRIBUTORLESS TYPE IGNITION SYSTEM IGNITION COIL RESISTANCE»(ref-22371-S15716401252001010300000) table.
- To check ignition coil secondary resistance, remove ignition coil. Using ohmmeter, check ignition coil secondary resistance. (Scheme 5) Replace ignition coil if secondary resistance is not within specification. See «DISTRIBUTORLESS TYPE IGNITION SYSTEM IGNITION COIL RESISTANCE»(ref-22371-S15716401252001010300000) table. Reinstall ignition coil and electrical connector.
Scheme 4
Scheme 5
| Application | Primary | Secondary |
|---|---|---|
| Cold (1) | .67-1.05 | 9300-16,000 |
| Hot (2) | .85-1.23 | 11,700-18,800 |
| (1) Cold is with temperature of 14-122°F (-10-50°C). (2) Hot is with temperature of 122-212°F (50-100°C). | ||
| (1) | Cold is with temperature of 14-122°F (-10-50°C). |
| (2) | Hot is with temperature of 122-212°F (50-100°C). |
DISTRIBUTORLESS TYPE IGNITION SYSTEM IGNITION COIL RESISTANCE - Ohms
CAMSHAFT POSITION SENSOR
- Disconnect electrical connector from camshaft position sensor. Camshaft position sensor is located on rear of cylinder head, just above the flywheel. (Scheme 6) Using ohmmeter, check resistance between electrical terminals on camshaft position sensor.
- Replace camshaft position sensor if resistance is not within specification. See «CAMSHAFT POSITION SENSOR RESISTANCE»(ref-22371-S14348548932001010300000) table. Reinstall electrical connector on camshaft position sensor.
| Application | Ohms |
|---|---|
| Cold (1) | 985-1600 |
| Hot (2) | 1265-1890 |
| (1) Cold is with temperature of 14-122°F (-10-50°C). (2) Hot is with temperature of 122-212°F (50-100°C). | |
| (1) | Cold is with temperature of 14-122°F (-10-50°C). |
| (2) | Hot is with temperature of 122-212°F (50-100°C). |
CAMSHAFT POSITION SENSOR RESISTANCE
Scheme 6
CRANKSHAFT POSITION SENSOR
- Disconnect electrical connector for crankshaft position sensor. Electrical connector is located near oil dipstick. (Scheme 7) Crankshaft position sensor is located at front (timing belt end) of engine, behind timing belt cover, near sprocket on crankshaft.
- Using ohmmeter, check resistance between electrical terminals on crankshaft position sensor. Replace crankshaft position sensor if resistance is not within specification. See «DISTRIBUTORLESS TYPE IGNITION SYSTEM CRANKSHAFT POSITION SENSOR RESISTANCE»(ref-22371-S36496392412001010300000) table. Reinstall electrical connector.
| Application | Ohms |
|---|---|
| Cold (1) | 985-1600 |
| Hot (2) | 1265-1890 |
| (1) Cold is with temperature of 14-122°F (-10-50°C). (2) Hot is with temperature of 122-212°F (50-100°C). | |
| (1) | Cold is with temperature of 14-122°F (-10-50°C). |
| (2) | Hot is with temperature of 122-212°F (50-100°C). |
DISTRIBUTORLESS TYPE IGNITION SYSTEM CRANKSHAFT POSITION SENSOR RESISTANCE
Scheme 7
IDLE SPEED & IGNITION TIMING
Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS article.
SUMMARY
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to TESTS W/CODES article. If no hard diagnostic trouble codes are found in self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.