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 | 185 (13.0) |
| Minimum Compression Pressure | 142 (10.0) |
| Maximum Variation Between Cylinders | 14 (1.0) |
4-CYLINDER 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 35) Place container under cold start injector pipe, deliver pipe or fuel filter. Cover union bolt with shop towel, and slowly loosen union bolt to relieve fuel pressure.
- Remove union bolt and gaskets. Install Fuel Pressure Gauge (SST 09268-45012) using NEW gaskets. (Scheme 35) Tighten union bolt. Reconnect negative battery cable.
- Install jumper wire between +B and FP terminals of data link connector. see scheme 1 The 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-21198-S22718661312001010300000) 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 the «FUEL PRESSURE SPECIFICATIONS»(ref-21198-S21445256382001010300000) 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 ) |
|---|---|
| Paseo | 41-42 (2.9-3.0) |
| (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 Tested | At Idle W/Vacuum psi (kg/cm 2 ) | At Idle W/O Vacuum psi (kg/cm 2 ) |
|---|---|---|
| Paseo | 33-37 (2.3-2.6) | 41-42 (2.9-3.0) |
FUEL PRESSURE SPECIFICATIONS
Scheme 35
FUEL PUMP CONTROL CIRCUIT
Note. For information on testing relays and fuel system components, see the SYSTEM/COMPONENT TESTS article. Relays may be identified by appropriate illustration in the THEORY/OPERATION article.
EFI Main Relay
The EFI fuse supplies constant battery voltage to EFI main relay. The EFI main relay provides battery voltage to +B terminal of circuit opening relay (some models) and data link connector. Depending on model, EFI main relay may either be turned on directly by ignition switch or by M-REL terminal of Engine Control Module (ECM). The EFI main relay may also provide battery voltage to +B and +B1 terminals of ECM when ignition is turned on. The EFI main relay is located in engine compartment relay box.
Note. Circuit opening relay is used on all models.
Circuit Opening Relay
Circuit opening relay controls fuel pump circuit. The Engine Control Module (ECM) receives an input signal at STA terminal when engine is cranking. Starter signal is also applied to STA terminal of circuit opening relay.
Starter signal energizes circuit opening relay during cranking. Circuit opening relay then provides voltage to fuel pump or fuel pump relay. The circuit opening relay is grounded by the ECM through the FC terminal.
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 36)
- Check secondary resistance between ignition coil positive (+) terminal and high tension wire terminal (coil wire tower). (Scheme 37) Replace ignition coil if resistance is not within specification. See appropriate «IGNITION COIL RESISTANCE»(ref-21198-S42804266252001010300000) table.
| Application | Primary | Secondary |
|---|---|---|
| Paseo | .40-.50 | 10,000-14,000 |
IGNITION COIL RESISTANCE (4-CYLINDER) - Ohms @ 68°F (20°C)
Scheme 36
Scheme 37
PICK-UP COIL RESISTANCE
- Note pick-up coil terminal identification on the distributor. (Scheme 38) Using ohmmeter, measure resistance between specified terminals. See «PICK-UP COIL RESISTANCE SPECIFICATIONS»(ref-21198-S31665495832001010300000) table.
- Replace distributor assembly if pick-up coil resistance is not within specification.
| Application | Pick-Up Coil Terminals | (1) Ohms |
|---|---|---|
| Paseo | G+ & G | 185-265 |
| Paseo | NE+ & NE | 370-530 |
| (1) With pick-up coil temperature at 14-104°F (-10-40°C). | ||
| (1) | With pick-up coil temperature at 14-104°F (-10-40°C). |
PICK-UP COIL RESISTANCE SPECIFICATIONS
PICK-UP COIL AIR GAP
- Using a flat, non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 39)and 7.
- Replace distributor assembly if pick-up coil air gap is not within specification. See «PICK-UP COIL AIR GAP SPECIFICATIONS»(ref-21198-S31740397392001010300000) table.
| Application | In. (mm) |
|---|---|
| All Models | .008-.016 (.20-.40) |
PICK-UP COIL AIR GAP SPECIFICATIONS
Scheme 38
Scheme 39
IDLE SPEED & IGNITION TIMING
Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS - 4-CYL article in this section.
SUMMARY
If no faults were found while performing the test procedures in this article, proceed to TESTS W/CODES article. If no hard diagnostic trouble codes are found while perfoming self-diagnostics, go to the TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.