Compression
| 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. |
Note. Before performing compression test, remove fuel pump relay on Continental, Contour, Cougar, Escort, Focus, Mystique and Town Car models. Start engine and run it until it stalls. This will reduce risk of fuel entering combustion chamber during engine cranking. When fuel pump relay is removed and engine is stalled, a Diagnostic Trouble Code (DTC) may set. Clear DTC(s) after performing compression test, if necessary.
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.
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 harness 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»(ref-2840-S38508909592000041300000) table under INERTIA FUEL SHUTOFF (IFS) SWITCH. Crank engine with IFS disconnected 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 switch to OFF position. 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»(ref-123327) table. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, see «TEST HB: NATURAL GAS FUEL DELIVERY SYSTEM»(ref-2842-S27467617572000041300000) for 4.6L Natural Gas or «TEST HC: GASOLINE FUEL DELIVERY SYSTEM»(ref-2842-S12551659512000041300000) for all others in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article for fuel delivery system diagnosis.
- With fuel pressure gauge still installed, cycle ignition switch on and off several times. Record fuel pressure. After one minute with ignition off, fuel pressure should remain within 5 psi (34 kPa) of maximum fuel pressure on gasoline engines and within 10 psi (69 kPa) of maximum fuel pressure on Crown Victoria (NGV). If fuel pressure remains within specification, system is capable of maintaining fuel pressure. If fuel pressure does not remain within specification, 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.
| Application | Ohms |
|---|---|
| Except NGV | 11-18 |
| Natural Gas Vehicle (NGV) | 3-6 |
| (1) Resistance values are for a single injector. | |
| (1) | Resistance values are for a single injector. |
INDIVIDUAL INJECTOR RESISTANCE (1)
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, see TEST HD: MISFIRE DETECTION MONITOR in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
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»(ref-2840-S38508909592000041300000) 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»(ref-2874) article. Continuity should not exist. Reset switch and ensure continuity exists between appropriate terminals.
| Application | Location | |
|---|---|---|
| Continental | Left Fender Apron Near Air Suspension Switch | |
| Contour, Cougar, Escort, Focus, LS & Mystique | Bottom Of Left "A" Pillar | |
| Crown Victoria, Grand Marquis & Town Car | In Trunk Behind Left Luggage Compartment Lining | |
| Mustang | Lower Left Rear Of Trunk | |
| Sable & Taurus | Behind Right Rear Luggage Compartment Lining | |
INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION
IGNITION CHECKS
Note. If vehicle does not start, see TEST A: NO-START/VEHICLE WILL NOT START in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
Note. For circuit identification, see appropriate wiring diagram in WIRING DIAGRAMS article.
EDIS (DISTRIBUTORLESS)
Note. Continental, Crown Victoria/Grand Marquis, Mustang and Town Car (4.6L), Taurus/Sable (3.0L 4V) and LS (3.0L and 3.9L) use Coil On Plug (COP). COP faults should set a DTC. For additional testing, see TEST JF: INTEGRATED IGNITION COIL ON PLUG FAILURE in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
- Spark Check Perform self diagnostic QUICK TEST to check for ignition-related fault codes, and repair as necessary. See «QUICK TEST»(ref-2842-S38840172182000041300000) in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article. If no fault codes are retrieved, check ignition system wiring harness for damage or loose connectors. See «WIRING DIAGRAMS»(ref-2874) 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, see «TEST A: NO-START/VEHICLE WILL NOT START»(ref-2842-S31252697232000041300000) in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
IGNITION COIL RESISTANCE
Note. For integrated ignition coil testing, see TEST JE: INTEGRATED IGNITION COIL FAILURE in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article. For integrated ignition Coil On Plug (COP) testing, see TEST JF: INTEGRATED IGNITION COIL ON PLUG FAILURE in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
| Application | Primary (Ohms) | Secondary (Ohms) |
|---|---|---|
| Coil On Plug | (1) | (1) |
| All Others | Less Than 5 | 12,000-14,500 |
| (1) Resistance values are not provided by manufacturer. | ||
| (1) | Resistance values are not provided by manufacturer. |
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: AIR INTAKE SYSTEM and TEST KE: IDLE AIR CONTROL (IAC) VALVE in SELF-DIAGNOSTICS - EEC-V (GASOLINE) 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
SUMMARY
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to SELF-DIAGNOSTICS - EEC-V (GASOLINE) article. If no fault codes are found in self-diagnostics, proceed to TROUBLE SHOOTING - NO CODES - EEC-V (GASOLINE) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.