INTRODUCTION
Note. Information for Escort applies to Escort ZX2, unless otherwise indicated.
The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.
The first step in diagnosing any driveability problem is verifying the symptom(s) with a test drive under the conditions the problem reportedly occurred.
Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from poor electrical connections, damaged/misrouted vacuum hoses or mechanical breakdowns. Before condemning the computerized system, perform each test listed in this article.
VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. Inspect air induction system for possible vacuum leaks.
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 specification if the lowest reading cylinder is within 75 percent of the highest reading cylinder.
| WARNING | DO NOT use ignition switch to crank engine 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. |
Exhaust System Backpressure
The exhaust system can be checked with a vacuum or pressure gauge. If using a pressure gauge, remove oxygen 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
Ensure following systems and components are in good condition and operating properly before diagnosing problems in fuel injection system
- Check battery and charging system condition.
- Check all wiring and vacuum connections.
- Check air cleaner and ducting.
- Check secondary ignition components.
- Check fuel delivery system.
- 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 cooling system.
- Check inertia fuel shutoff switch.
- Check for blown head gasket (liquid in cylinder).
- Check for improperly installed electronic equipment such as anti-theft system, CB radio, cellular telephone or stereo.
FUEL PRESSURE RELEASE
- Remove fuel cap to release fuel tank pressure. Remove relief valve service port cap. Relief valve service port is located on fuel supply manifold. Using Fuel Pressure Gauge (T80L-9974-B), release fuel pressure from relief valve (Schrader valve).
- If fuel pressure gauge is not available, disconnect electrical connector to IFS switch. For IFS switch location, see «INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION»(/mercury/grand-marquis/iii-1997-2002/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures) table under INERTIA FUEL SHUTOFF (IFS) SWITCH. 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 . |
- Visually inspect fuel system, including fuel lines, connections, injectors and electrical connections. Ensure Inertia Fuel Shutoff (IFS) switch is not tripped. Check condition of battery and fuses. Ensure fuel level in tank is sufficient.
- Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and increase engine speed to 2500 RPM. If engine will not start, cycle ignition switch several times. Measure and record fuel pressure. See «FUEL PRESSURE SPECIFICATIONS»(/mercury/grand-marquis/iii-1997-2002/remont/specifications/#fuel-system-pressure-specifications) article. table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to TEST HB in SELF-DIAGNOSTICS - EEC-V article (4.6L Natural Gas) or TEST HC in SELF-DIAGNOSTICS - EEC-V (all others) article for fuel system diagnosis.
- With fuel pressure gauge still installed, cycle ignition switch on and off several times. Record fuel pressure. If fuel pressure is at least 25 psi (172 kPa) after one minute with ignition off, system is capable of maintaining fuel pressure. If fuel pressure is not at least 25 psi after one minute with ignition off, check for leaking fuel injectors or fuel pressure regulator.
Fuel Injector Resistance
Disconnect injector harness connectors. Using digital ohmmeter, measure resistance between injector terminals. See INDIVIDUAL INJECTOR RESISTANCE table. Replace any injector not within specification.
Fuel Injector Check
Ensure engine mechanical condition is okay. Ensure no vacuum leaks exist and ignition system is operating properly. Start engine and allow to idle. If engine will not start, crank engine for 10 seconds. Using a stethoscope, listen for clicking sound at each injector. If clicking sound is heard, fuel injector is operating. If clicking sound is not heard, go to TEST HD in SELF-DIAGNOSTICS - EEC-V article.
| Engine | Ohms |
|---|---|
| Natural Gas Models | 4-6 |
| All Other Models | 11-18 |
| (1) Resistance values are for a single injector. | |
| (1) | Resistance values are for a single injector. |
INDIVIDUAL INJECTOR RESISTANCE (1)
INERTIA FUEL SHUTOFF (IFS) SWITCH
| WARNING | DO NOT reset IFS switch until fuel system has been inspected for leaks and repaired if necessary. |
- If IFS switch is tripped, engine cannot be restarted until switch is manually reset. To reset IFS switch, depress switch button. For IFS switch location, see «INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION»(/mercury/grand-marquis/iii-1997-2002/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures) table.
- To test IFS switch, turn ignition off. Remove IFS switch. Shake IFS switch to force it into tripped position (switch open). Check continuity between appropriate IFS switch terminals. See WIRING DIAGRAMS article. Continuity should not exist. Reset switch and ensure continuity exists between appropriate terminals.
| Application | Location | |
|---|---|---|
| Continental | Left Fender Apron Near Suspension Switch | |
| Contour, Cougar & Mystique | Behind Left Kick Panel | |
| Escort & Tracer | ||
| Coupe & Sedan | Right Side Of Trunk | |
| Wagon | Right Side Of Cargo Area | |
| Mustang | Lower Left Rear Of Trunk | |
| Sable & Taurus | Right Side Of Trunk Behind Wheel Well | |
| Town Car | Above Left Rear Wheel Well | |
| All Others | In Trunk On Left Hinge Support Or Behind Trim Panel | |
INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION
IGNITION CHECKS
Note. If vehicle does not start, go to TEST A in SELF-DIAGNOSTICS - EEC-V article.
Note. For circuit identification, see appropriate wiring diagram in WIRING DIAGRAMS article.
EDIS (DISTRIBUTORLESS)
Note. Continental, Crown Victoria (3.0L, 3.9L and 4.6L), Grand Marquis (3.0L, 3.9L and 4.6L), Mustang (4.6L), Taurus SHO (3.4L), and Town Car use Coil On Plug (COP). COP faults should set a DTC. For additional testing, see TEST JF in SELF-DIAGNOSTICS - EEC-V article.
- Spark Check Perform self diagnostic QUICK TEST to check for ignition-related fault codes, and repair as necessary. See QUICK TEST in SELF-DIAGNOSTICS - EEC-V article. If no fault codes are retrieved, check ignition system wiring harness for damage or loose connectors. See WIRING DIAGRAMS article. Clean or repair connectors as necessary.
- If wiring and connectors are okay, use Neon Bulb Spark Tester (D8IP-6666-A) to check for spark at each spark plug while cranking engine. If spark is strong and consistent at each spark plug (one spark per crankshaft revolution), ignition system is okay. If spark is not present, go to TEST A in SELF-DIAGNOSTICS - EEC-V article.
IGNITION COIL RESISTANCE
| Application | Primary (Ohms) | Secondary (Ohms) |
|---|---|---|
| Coil On Plug | (1) | (1) |
| All Others | (2) Less Than 5 | (2) 12,000-14,500 |
| (1) Resistance values are not provided by manufacturer. For testing, refer to TEST JF in SELF-DIAGNOSTICS - EEC-V article. (2) Resistance values are not provided by manufacturer. For testing, refer to TEST JE in SELF-DIANGOSTICS - EEC-V article. | ||
| (1) | Resistance values are not provided by manufacturer. For testing, refer to TEST JF in SELF-DIAGNOSTICS - EEC-V article. |
| (2) | Resistance values are not provided by manufacturer. For testing, refer to TEST JE in SELF-DIANGOSTICS - EEC-V article. |
IGNITION COIL RESISTANCE
IDLE SPEED & IGNITION TIMING
Idle speed and ignition timing are not adjustable. If idle speed and ignition timing are incorrect, see TEST HU and TEST KE in SELF-DIAGNOSTICS - EEC-V article.
IDLE MIXTURE ADJUSTMENT
Idle mixture is not adjustable. If idle mixture is incorrect, see TEST H in SELF-DIAGNOSTICS - EEC-V article.
IGNITION TIMING
Note. On all models with distributorless electronic ignition, manufacturer does not recommend checking ignition timing, as faulty readings are common and timing is not adjustable.
| Application | Degrees BTDC |
|---|---|
| All Models | (1) 8-12 |
| (1) Timing is not adjustable. | |
| (1) | Timing is not adjustable. |
BASE IGNITION TIMING
THROTTLE POSITION (TP) SENSOR ADJUSTMENT
Note. For TP sensor specifications and adjustment procedures, see appropriate ON-VEHICLE ADJUSTMENTS article in the appropriate manual.
SUMMARY
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to SELF-DIAGNOSTICS - EEC-V article. If no fault codes are found in self-diagnostics, proceed to TROUBLE SHOOTING - NO CODES EEC-V article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.