Compression
Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. Compression pressures are considered within specifications if the lowest reading cylinder is within 75 percent of the highest reading cylinder.
| WARNING | DO NOT use ignition switch during compression tests on fuel injected vehicles. 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. |
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 2 psi, exhaust system or catalytic converter is plugged.
If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port. 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.
PRELIMINARY CHECKS
Check that the following systems and components are in good condition and operating properly before diagnosing problems in fuel injection system
- Check battery condition.
- Check all wiring and vacuum connections.
- Check air cleaner and ducting.
- Check state of tune.
- Check fuel delivery system.
- Check cooling system.
- Check inertia switch.
- Check for hydrostatic lock (liquid in cylinder).
- Check fuel tank contents and fuel gauge accuracy.
- Check for dirt, water or other contamination in fuel.
- Check fuel lines and fittings for leaks.
- Check fuel delivery system for proper pressure and volume.
- Check for inoperative fuel injectors.
- Check for improperly installed electronic equipment such as CB radio, cellular telephone or stereo.
1.8L & 1.9L
Depress retaining clips and remove rear seat cushion. Disconnect fuel pump connections. Start engine and operate until it stalls. Turn ignition off. Reconnect fuel pump. Install rear seat cushion.
2.2L
Remove fuel pump relay or move reset button on inertia switch. Start engine and operate until it stalls. Turn ignition off.Reconnect fuel pump relay or reset inertia switch. See INERTIA SWITCH under FUEL SYSTEM.
All Others
- Remove fuel cap to release fuel tank pressure. Remove relief valve cap. Relief valve is located on fuel supply manifold. Using EFI Pressure Gauge (T80L-9974-B), release fuel pressure from relief valve (Schrader valve).
- If fuel pressure gauge is not available, disconnect electrical connector to inertia switch located on left side of luggage compartment. Crank engine for 15 seconds to reduce system pressure.
FUEL PRESSURE
| WARNING | ALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT allow fuel to contact engine or electrical components. See FUEL PRESSURE RELEASE under FUEL SYSTEM. |
Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.
Scheme 2
- Release fuel pressure. Install fuel pressure gauge. Using a jumper lead, ground the fuel pump lead at the SELF-TEST connector. (Scheme 2) Turn ignition on, but DO NOT start engine. This activates the fuel pump. CAUTION: DO NOT activate fuel pump for long periods or engine may hydrostatically (liquid) lock.
- Measure and record KOEO fuel pressure. Start engine. Measure and record KOER fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123318) article. Turn ignition off and monitor fuel pressure for one minute. Fuel pressure should not drop more than 5 psi (kg/cm 2 ).
- If fuel pressure is within specification, test is complete. If fuel pressure is not within specification, check fuel filter and lines for restriction(s). Repair or replace as necessary. If fuel pressure is still not within specification, install fuel pressure gauge (if removed). CAUTION: Inspect fuel system for leaks or damage before testing fuel pump.
- Start engine and observe fuel pressure gauge. Gently squeeze fuel return hose. If fuel pressure increases while squeezing fuel return hose, replace fuel pressure regulator. If fuel pressure does not change while squeezing fuel return hose, check for plugged fuel inlet strainer or defective fuel pump. Repair as necessary.
Note. For fuel circuit test information, see appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section.
Fuel Injector Check
- Connect tachometer to engine. Run engine at idle. Disconnect and reconnect injectors individually. When disconnected, each injector should cause a momentary drop in engine speed of at least 100 RPM. Engine RPM drop should only be momentary as ECA will attempt to reestablish correct idle RPM.
- Replace any injectors that do not cause sufficient drop in engine speed. When test is complete, check idle speed. Refer to emission control specifications on decal in engine compartment or IDLE SPEED & IGNITION TIMING.
Fuel Injector Circuit
Disconnect injector harness connectors. Using digital ohmmeter, check connector terminal resistance of each injector. See INDIVIDUAL INJECTOR RESISTANCE . On non-sequential PFI engines, disconnect injector bank harness connector. Check resistance of injector bank. See INJECTOR BANK RESISTANCE . Repair wiring or any injector not within specification.
| Engine | Ohms |
|---|---|
| All Models | 13-16 |
| (1) Resistance values are for a single injector. | |
| (1) | Resistance values are for a single injector. |
INDIVIDUAL INJECTOR RESISTANCE (1)
| Engine | Ohms |
|---|---|
| 2.3L | 6.0-8.5 |
| 3.0L | 4.0-5.5 |
| 5.0L | 0.5-3.0 |
| (1) Resistance values are for non-sequential PFI engines only. | |
| (1) | Resistance values are for non-sequential PFI engines only. |
INJECTOR BANK RESISTANCE (1)
Note. For additional testing and information, see FUEL SYSTEM in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
INERTIA SWITCH
- If inertia switch is tripped, engine cannot be restarted until switch is manually reset. To reset inertia switch, depress switch button. Inertia switches may be found in the following locations: On Sable and Taurus, in left side of trunk (except station wagon). On Sable and Taurus station wagon models, behind access door in right rear cargo area. On all other vehicles, in trunk on left hinge support or behind trim panel. CAUTION: DO NOT reset inertia switch until fuel system has been inspected for leaks.
- To test inertia switch, turn ignition off. Remove inertia switch. Shake inertia switch to force switch into tripped position (switch open).Measure resistance of switch. See «INERTIA SWITCH RESISTANCE»(ref-22730-S34067851822001010300000) . Replace switch if resistance is incorrect, or if switch cannot be tripped.
| Switch Position | Ohms |
|---|---|
| Open (1) | 10,000+ |
| Closed (2) | 0-5 |
| (1) Indicates switch is in the tripped position. (2) Indicates switch is in the set position. | |
| (1) | Indicates switch is in the tripped position. |
| (2) | Indicates switch is in the set position. |
INERTIA SWITCH RESISTANCE
IGNITION COIL RESISTANCE
| Application | Primary | Secondary | |
|---|---|---|---|
| 1.8L | .08-1.6 | 6000-30,000 | |
| 2.2L | |||
| Non-Turbo | 1.04-1.27 | 7100-9700 | |
| Turbo | .72-.88 | 10,300-13,900 | |
| DIS | (1) | (1) | |
| EDIS | (1) | (1) | |
| TFI-IV | 0.8-1.6 | 8000-11,500 | |
| (1) Resistance values are not provided by mfg. For testing procedure, see IGNITION SYSTEMS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. | |||
| (1) | Resistance values are not provided by mfg. For testing procedure, see IGNITION SYSTEMS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. |
IGNITION COIL RESISTANCE
Spark Output Check
- Check EEC-IV system for fault codes and repair if necessary. See QUICK TEST in G - EEC IV TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no fault codes are retrieved, check ignition system wiring harness connectors for corrosion and tight fit. (Scheme 3)or (Scheme 4).
- If wiring and connectors are okay, use Neon Bulb Spark Tester (D89P-6666-A) to check for spark at each spark plug wire while cranking engine. If spark is consistent and equal at each spark plug (one spark per crankshaft revolution), ignition system is okay. If spark is not present, go to IGNITION SYSTEMS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
Scheme 3
Scheme 4
- Check EEC-IV system for fault codes and repair if necessary. See QUICK TEST in G - EEC IV TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no fault codes are retrieved, check ignition system wiring harness connectors for corrosion and tight fit. Repair or replace as necessary.
- If wiring and connectors are okay, use Neon Bulb Spark Tester (D89P-6666-A) to check for spark at each spark plug wire while cranking engine. If spark is consistent and equal at each spark plug (one spark per crankshaft revolution), ignition system is okay. If spark is not present, go to IGNITION SYSTEMS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
- Check EEC-IV system for fault codes and repair if necessary. See QUICK TEST in G - EEC IV TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no fault codes are retrieved, check ignition system wiring harness connectors for damage, corrosion and tight fit. (Scheme 5), (Scheme 6) or (Scheme 7).
- If no fault codes are retrieved and vehicle will start, go to TESTS W/O CODES article in the ENGINE PERFORMANCE Section. If no fault codes are retrieved and vehicle is a no-start, connect a high-output spark tester between ignition coil wire and engine ground. Check for spark at coil wire while cranking engine. A consistent Blue spark should be present.
- If spark is present, go to step 4). If no spark is present, remove distributor cap and crank engine to ensure distributor rotates. If okay, check resistance of coil secondary wire. Resistance should be less than 7000 ohms per foot. Service coil wire if necessary and retest. If spark is not present, go to IGNITION SYSTEMS in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
- If a consistent Blue spark is present at coil wire during cranking, inspect distributor cap and rotor for cracks or carbon tracking. Service as necessary and test spark output at spark plugs. If spark is present at spark plugs and engine will not start, go to TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
Scheme 5
Scheme 6
Scheme 7
IDLE SPEED & IGNITION TIMING
Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see IDLE SPEED in ADJUSTMENTS article in the ENGINE PERFORMANCE Section.
4-CYLINDER IGNITION TIMING
Note. Ignition timing is not adjustable on models with DIS or EDIS.
| Application | Degrees BTDC @ RPM | |
|---|---|---|
| 1.8L | (1) 10 @ 700-800 | |
| 1.9L | (1) 10 @ 700-800 | |
| 2.2L | ||
| Non-Turbo | 6 @ 725-775 | |
| Turbo | (1) 9 @ 725-775 | |
| 2.3L | ||
| Auto. Trans. | (2) 10 @ 500-800 | |
| Man. Trans. | (2) 10 @ 450-750 | |
| (1) With STI terminal grounded. (2) With SPOUT in-line connector disconnected. | ||
| (1) | With STI terminal grounded. |
| (2) | With SPOUT in-line connector disconnected. |
4-CYLINDER BASE IGNITION TIMING
4-CYLINDER IDLE SPEED
Engine idle RPM is fixed and cannot be changed by standard adjustments. A scan tool must be used because the control strategy and idle speed is controlled by the ECA. See IDLE SPEED in ADJUSTMENTS article in the ENGINE PERFORMANCE Section.
V6 IGNITION TIMING
Note. Ignition timing is not adjustable on models with DIS.
| Application | (1) Degrees BTDC @ RPM |
|---|---|
| 3.0L | 10 @ 770-830 |
| 3.0L SHO | 10 @ 550-725 |
| 3.8L | (2) |
| (1) With SPOUT in-line connector disconnected. (2) Refer to underhood decal for specification. | |
| (1) | With SPOUT in-line connector disconnected. |
| (2) | Refer to underhood decal for specification. |
V6 BASE IGNITION TIMING
V6 IDLE SPEED
Engine idle RPM is fixed and cannot be changed by standard adjustments. A scan tool must be used because the control strategy and idle speed is controlled by the ECA. See IDLE SPEED in ADJUSTMENTS article in the ENGINE PERFORMANCE Section.
V8 IGNITION TIMING
Note. Ignition timing is not adjustable on models with EDIS.
| Application | Degrees BTDC @ RPM |
|---|---|
| 4.6L & 5.0L (1) | 10 @ 575-725 |
| (1) On 4.6L, ignition timing is not adjustable. | |
| (1) | On 4.6L, ignition timing is not adjustable. |
V8 BASE IGNITION TIMING
V8 IDLE SPEED
Engine idle RPM is fixed and cannot be changed by standard adjustments. A scan tool must be used because the control strategy and idle speed is controlled by the ECA. See IDLE SPEED in ADJUSTMENTS article in the ENGINE PERFORMANCE Section.
EXCEPT 1.8L & 2.2L
- Connect Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Connect digital voltmeter positive lead to pin No. 47 and negative voltmeter lead to pin No. 46. Turn ignition on. Slowly depress accelerator pedal. Check voltmeter reading. See «TPS VOLTAGE SPECIFICATIONS (EXCEPT 1.8L & 2.2L)»(ref-22730-S07482883072001010300000) .
- If voltage is not as specified, ensure throttle stop screw and linkage are adjusted correctly. Remove sensor and check for damaged, corroded or misadjusted pins. If okay, install sensor. Ensure sensor is seated correctly. Repeat step 1). If voltage is not as specified, replace sensor and perform KOEO test. See G - EEC IV TESTS W/CODES article in the ENGINE PERFORMANCE Section.
| Throttle Angle | (1) Voltage |
|---|---|
| 0° | .50 |
| 10° | .97 |
| 20° | 1.44 |
| 30° | 1.90 |
| 40° | 2.37 |
| 50° | 2.84 |
| 60° | 3.31 |
| 70° | 3.78 |
| 80° | 4.24 |
| (1) Voltage values may vary up to 15 percent. | |
| (1) | Voltage values may vary up to 15 percent. |
TPS VOLTAGE SPECIFICATIONS
SUMMARY
If no faults were found while performing BASIC TESTING , proceed to TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no hard codes are found in self-diagnostics, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.