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Engine Controls - Basic Testing - 1.8L: Other Mercury Tracer I

Testing & Diagnostics 1 illustration ~987 words

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.

WARNINGDO 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

  1. Check battery and charging system condition.
  2. Check all wiring and vacuum connections.
  3. Check air cleaner and ducting.
  4. Check state of tune.
  5. Check fuel delivery system.
  6. Check cooling system.
  7. Check inertia fuel shutoff switch.
  8. Check for hydrostatic lock (liquid in cylinder).
  9. Check fuel tank contents and fuel gauge accuracy.
  10. Check for dirt, water or other contamination in fuel.
  11. Check fuel lines and fittings for leaks.
  12. Check fuel delivery system for proper pressure and volume.
  13. Check for inoperative fuel injectors.
  14. Check for improperly installed electronic equipment such as CB radio, cellular telephone or stereo.

FUEL PRESSURE RELEASE

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.

FUEL PRESSURE

WARNINGALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT allow fuel to contact engine or electrical components. See FUEL PRESSURE RELEASE.

Note. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article.

Scheme 116

Scheme 116
Scheme 116
  1. Release fuel pressure. See FUEL PRESSURE RELEASE. Install fuel pressure gauge. Connect a jumper wire between fuel pump test terminal at the Data Link Connector (DLC) and ground. (Scheme 116) Turn ignition on, but DO NOT start engine. This activates the fuel pump.
  2. Measure and record Key On, Engine Off (KOEO) fuel pressure. Start engine. Measure and record Key On, Engine Running (KOER) fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123321) article. Turn ignition off and monitor fuel pressure for one minute. Fuel pressure should not drop more than 5 psi (34 kPa).
  3. 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.
  4. 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 additional fuel system testing information, see the SYSTEM/COMPONENT TESTS - EEC (1.8L) article.

Fuel Injector Check

  1. 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 Powertrain Control Unit (PCM) will attempt to re-establish correct idle RPM.
  2. 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. See IDLE SPEED & IGNITION TIMING.

Fuel Injector Resistance

Disconnect injector harness connectors. Using digital ohmmeter, measure resistance between injector terminals. If resistance is not 11-19 ohms, replace injector.

Note. For additional testing and information, see FUEL SYSTEM in the SYSTEM/COMPONENT TESTS - EEC (1.8L) article.

INERTIA FUEL SHUTOFF (IFS) SWITCH

  1. 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 table. INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION Application Location Sedan Right Side Of Trunk Wagon Behind Access Door In Right Rear Cargo Area
  2. 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 the «WIRING DIAGRAMS - 1.8L»(ref-23203) article in the ENGINE PERFORMANCE section. Continuity should not exists. Reset switch and ensure continuity exists between appropriate terminals.

IGNITION CHECKS

Note. For circuit identification, see wiring diagram in the WIRING DIAGRAMS - 1.8L article in the ENGINE PERFORMANCE section.

Note. If an ignition failure occurs, ignition system may operate with limited ability using Failure Mode Effects Management (FMEM). When this occurs, trouble codes should be present, engine may be hard to start and dwell, and timing will not change.

Note. This test does not cover Camshaft Position (CMP) sensor or Crankshaft Position (CKP) sensor testing. CMP and CKP sensors should set a Diagnostic Trouble Code (DTC) if defective. To access trouble codes, see QUICK TEST in the TESTS W/CODES - EEC (1.8L) article in the ENGINE PERFORMANCE section.

IGNITION COIL RESISTANCE

ApplicationPrimary (Ohms)Secondary (Ohms)
1.8L0.8-1.66000-30,000
(1) Resistance value is not provided by manufacturer. For testing, see IGNITION SYSTEMS in the SYSTEM/COMPONENT TESTS - EEC (1.8L) article in the ENGINE PERFORMANCE section.
(1)Resistance value is not provided by manufacturer. For testing, see IGNITION SYSTEMS in the SYSTEM/COMPONENT TESTS - EEC (1.8L) article in the ENGINE PERFORMANCE section.

4-CYLINDER IGNITION COIL RESISTANCE (1)

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see the ADJUSTMENTS - 1.8L article in the ENGINE PERFORMANCE section.

IGNITION TIMING

ApplicationDegrees BTDC @ Idle
1.8L(1) 9-11
(1) With STI terminal of DLC grounded.
(1)With STI terminal of DLC grounded.

4-CYLINDER BASE IGNITION TIMING

IDLE SPEED

Idle speed is adjustable. For further information, see the ADJUSTMENTS - 1.8L article in the ENGINE PERFORMANCE section.

ModelRPM
1.8L(1) 700-800
(1) With STI terminal of DLC grounded.
(1)With STI terminal of DLC grounded.

IDLE SPEED SPECIFICATIONS

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to the TESTS W/CODES - EEC (1.8L) article. If no hard codes are found in self-diagnostics, proceed to the TESTS W/O CODES - EEC (1.8L) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

More articles — Engine Controls - Basic Testing - 1.8L