Compression
Check engine mechanical condition with a compression gauge, vacuum gauge, or engine analyzer. See engine analyzer manual for specific instructions.
| 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 | Psi (kg/cm 2 ) | |
|---|---|---|
| Normal Compression Pressure | ||
| Turbo | 156 psi (10.9 kg/cm 2 ) | |
| Non-Turbo | 185 psi (13.0 kg/cm 2 ) | |
| Minimum Compression Pressure | ||
| Turbo | 128 psi (9.0 kg/cm 2 ) | |
| Non-Turbo | 156 psi (10.9 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. If using a 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, exhaust system or catalytic converter is plugged.
If using a vacuum gauge, 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, 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. All models use in-tank fuel pump. Fuel pump contains internal relief valve and check valve.
- Ensure battery is fully charged and ignition is off. Disconnect negative battery cable. Disconnect electrical connector from cold start injector (if equipped).
- Note location of fuel pressure gauge installation. (Scheme 3)and (Scheme 4). Place container under cold start injector pipe, delivery pipe or fuel filter. Cover union bolt with shop towel. Slowly loosen union bolt to relieve fuel pressure.
- Remove union bolt and gaskets. Install Fuel Pressure Gauge (SST 09268-45012) using NEW gaskets. (Scheme 3)and (Scheme 4). Tighten union bolt. Reconnect negative battery cable.
- Install jumper wire between +B and FP terminals of data link connector. see scheme 1 Data link connector is located in engine compartment.
- Turn ignition on and note fuel pressure. Fuel pressure should be within specification. See «FUEL PUMP PERFORMANCE»(ref-21327-S36612829702001010300000) table.
- If fuel pressure exceeds specification, replace fuel pressure regulator. If fuel pressure is less than specified, check for defective fuel lines, connections, fuel pump, fuel filter or fuel pressure regulator.
- Remove jumper wire from data link connector. Start engine and allow to idle. Disconnect and plug vacuum line at fuel pressure regulator. Note fuel pressure.
- Reconnect vacuum hose on fuel pressure regulator and note fuel pressure. Fuel pressure should be within specification. See appropriate «REGULATED FUEL PRESSURE»(ref-21327-S01430589802001010300000) table.
- If fuel pressure is not within specification, check for defective vacuum hose or fuel pressure regulator. 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. Install cold start injector electrical connector (if equipped). Install negative battery cable.
Note. For more information on checking fuel injectors and other fuel sub-systems, see SYSTEM/COMPONENT TESTS article.
| Application | (1) psi (kg/cm 2 ) |
|---|---|
| Turbo | 33-40 (2.3-2.8) |
| Non-Turbo | 38-44 (2.7-3.1) |
| (1) Check fuel pressure with jumper wire installed between data link connector +B and FP terminals, ignition on and engine off. | |
| (1) | Check fuel pressure with jumper wire installed between data link connector +B and FP terminals, ignition on and engine off. |
FUEL PUMP PERFORMANCE
| Application Type | At Idle W/Vacuum | At Idle W/O Vacuum |
|---|---|---|
| Turbo | 24-31 (1.7-2.2) | 33-40 (2.3-2.8) |
| Non-Turbo | 28-34 (2.0-2.4) | 38-44 (2.7-3.1) |
REGULATED FUEL PRESSURE
Scheme 3
Scheme 4
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.
EFI Main Relay & No. 2 EFI Relay (Turbo)
The No. 1 EFI fuse supplies constant battery voltage to EFI main relay. The EFI main relay is turned on by M-REL terminal of Engine Control Module (ECM). When EFI main relay is turned on, voltage is supplied to No. 2 EFI relay, +B terminal of ECM, and data link connector. The EFI main relay and No. 2 EFI relay are located in engine compartment relay box.
The No. 2 EFI fuse supplies constant battery voltage to No. 2 EFI relay. When No. 2 EFI relay is energized by voltage supplied from EFI main relay, relay closes and voltage is provided to +B and +B1 terminals of fuel pump Electronic Control Unit (ECU). Fuel pump ECU is located in left rear corner of the trunk. The ECM provides signals to fuel pump ECU for controlling fuel pump operation. Fuel pump ECU then provides voltage to the fuel pump.
EFI Main Relay (Non-Turbo)
The No. 1 EFI fuse supplies constant battery voltage to EFI main relay, located in engine compartment relay box. The EFI main relay is turned on by M-REL terminal of Engine Control Module (ECM). When EFI main relay is turned on, voltage is supplied to +B and +B1 terminals of ECM, data link connector, and +B terminal of fuel pump Electronic Control Unit (ECU). Fuel pump ECU is located in left rear corner of trunk. The ECM provides signals to fuel pump ECU for controlling fuel pump operation. Fuel pump ECU then provides voltage to the fuel pump.
IGNITION COIL RESISTANCE
- Disconnect wiring from ignition coil so ignition coil is isolated from system. Using ohmmeter, check primary resistance between ignition coil positive (+) and negative (-) terminals. (Scheme 5)
- Check secondary resistance between ignition coil positive (+) terminal and high tension terminal (coil wire tower). (Scheme 6) Replace ignition coil if resistance is not within specification. See appropriate «IGNITION COIL RESISTANCE»(ref-21327-S18189988392001010300000) table.
| Application | Primary | Secondary |
|---|---|---|
| Supra Non-Turbo | .21-.33 | 6400-11,100 |
IGNITION COIL RESISTANCE - Ohms @ 68°F (20°C)
Scheme 5
Scheme 6
PICK-UP COIL RESISTANCE
Note pick-up coil terminal identification on the distributor. (Scheme 7) Using ohmmeter, measure resistance between specified terminals. See PICK-UP COIL RESISTANCE SPECIFICATIONS table. Replace distributor assembly if pick-up coil resistance is not within specification.
| Application | Pick-Up Coil Terminals | (1) Ohms |
|---|---|---|
| Non-Turbo | G1 & G | 125-200 |
| Non-Turbo | G2 & G | 125-200 |
| Non-Turbo | NE & G | 155-250 |
| (1) Specification is with pick-up coil temperature of 14-122°F (-10-50°C). | ||
| (1) | Specification is with pick-up coil temperature of 14-122°F (-10-50°C). |
PICK-UP COIL RESISTANCE SPECIFICATIONS
Scheme 7
PICK-UP COIL AIR GAP
- Using non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 8)
- Replace distributor assembly if pick-up coil air gap is not within specification. See «PICK-UP COIL AIR GAP SPECIFICATIONS»(ref-21327-S10427482382001010300000) table.
| Application | In. (mm) |
|---|---|
| Non-Turbo | .008-.020 (.20-.51) |
PICK-UP COIL AIR GAP SPECIFICATIONS
Scheme 8
- Disconnect negative battery cable. Remove oil filler cap. Remove timing belt cover and gasket, located above ignition coils. see scheme 8
- Remove PCV hoses. Disconnect engine wiring clamps on ignition coils. Disconnect electrical connectors from ignition coils.
- Using ohmmeter, measure ignition coil primary resistance between positive (+) and negative (-) terminals of each ignition coil. These are the terminals that electrical connector was installed on.
- Replace ignition coil if primary coil resistance is not.54-.84 ohms at 14-122°F (-10-50°C). The ignition coil secondary resistance cannot be measured. Reinstall electrical connectors on ignition coils, timing belt cover, gasket and negative battery cable.
CAMSHAFT POSITION SENSOR
- Disconnect electrical connector from camshaft position sensors. see scheme 8 Using ohmmeter, measure resistance between both electrical terminals of each camshaft position sensor.
- Replace camshaft position sensor if resistance is not 835-1400 ohms at 14-122°F (-10-50°C) on Nippondenso sensors, or 985-1600 ohms at 14-122°F (-10-50°C) on Aisan sensors. Reinstall electrical connector on camshaft position sensors.
CRANKSHAFT POSITION SENSOR
- Remove air tube for charge air cooler, located near front of crankshaft, to access crankshaft position sensor. see scheme 8
- Disconnect electrical connector from crankshaft position sensor. Using ohmmeter, measure resistance between both electrical terminals of crankshaft position sensor.
- Replace crankshaft position sensor if resistance is not 835-1400 ohms at 68°F (20°C) on Nippondenso sensors, or 985-1600 ohms at 68°F (20°C) on Aisan sensors. Reinstall electrical connector on crankshaft position sensor. Reinstall air tube.
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 appropriate article listed below.
TESTS W/CODES - NON-TURBO
TESTS W/CODES - TURBO
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.