Engine Controls - Basic Diagnostic Procedures Lincoln Continental VIII

INTRODUCTION

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 customer's complaint 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 mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed.

Note. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

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. See VACUUM DIAGRAMS article to verify routing and connections (if necessary). 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 specifications if the lowest reading cylinder is within 75 percent of the highest reading cylinder.

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. 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 a vacuum gauge is used, 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, exhaust system should be checked for a restriction.

PRELIMINARY CHECKS

Check that the following systems and components are in good condition and operating properly before diagnosing problems in fuel injection system

1. Battery condition
2. State of tune
3. Fuel delivery system
4. All wiring and vacuum connections
5. Air cleaner and ducting
6. Cooling system

Engine Does Not Crank

Check for hydrostatic lock (liquid in cylinder). Repair as needed. Check for starting and charging system problems.

Engine Cranks But Will Not Start

1. Check fuel tank contents and fuel gauge accuracy. Check for dirt, water or other contamination in fuel.
2. Check ignition system for strong secondary current at spark plugs. If no spark exists or if spark is weak, repair ignition system problem first.
3. Check fuel lines and fittings for leaks. If no leaks are found, check fuel delivery system for proper pressure and volumes. Reset inertia switch (if necessary).
4. Check for a defective fuel injector or coolant temperature sensor. Ensure that TPS is not sticking. ALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT allow fuel to contact engine or electrical components.

1.8L

Depress retaining clips and remove rear seat cushion. Disconnect fuel pump connections. Start engine and operate until it stalls. Turn off ignition and reconnect fuel pump. Install rear seat cushion.

2.2L

Remove fuel pump relay, or move reset switch on inertia switch. Start engine and operate until it stalls. Turn ignition off. Reconnect fuel pump relay, or reset inertia switch.

All Others

Remove fuel cap to release fuel tank pressure. Using EFI Pressure Gauge (T80L-9974-B), release fuel pressure from relief valve. Relief valve is located on fuel supply manifold.

FUEL PRESSURE

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

Release fuel pressure. Install fuel pressure gauge. Fuel pump may be activated by grounding the fuel pump lead at the SELF-TEST connector. Using a jumper lead, ground the "FP" terminal with the ignition on. This activates the fuel pump. (Scheme 1) For additional circuit test information, see appropriate TESTS W/CODES article in this section.

Scheme 1

Fuel Injector Check

1. Connect tachometer to engine. Run engine at idle. Disconnect and reconnect injectors individually. If each injector causes a momentary drop in engine speed of at least 100 RPM, injectors are giving proper fuel delivery. RPM drop should only be momentary as ISC 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, turn engine off. To check curb idle, refer to emission control specifications on decal in engine compartment or IDLE SPEED & IGNITION TIMING.

Fuel Injector Circuit

Disconnect all injector harness connectors. Using digital ohmmeter, check resistance across terminals of each injector. See INDIVIDUAL INJECTOR RESISTANCE . Disconnect injector bank harness connector and check resistance of injector bank. See INJECTOR BANK RESISTANCE . Repair wiring or any injector not within specification.

INDIVIDUAL INJECTOR RESISTANCE (1)

INJECTOR BANK RESISTANCE

Note. For further component testing and information, see appropriate TESTS W/CODES article in this section.

INERTIA SWITCH

1. In event of a collision, electrical contacts in inertia switch open and fuel pump automatically shuts off. Fuel pump will shut off even if engine does not stop running. Engine will stop due to lack of fuel.
2. Engine cannot be restarted until inertia switch is manually reset. To reset inertia switch, depress button on switch. Inertia switches may be found in the following locations: On Crown Victoria and Grand Marquis station wagon models, in the left rear side storage compartment. On RWD vehicles (except wagons), in trunk, on the left hinge support or behind trim panel. On Sable and Taurus, on left side of trunk (except station wagon). On Taurus and Sable 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.

Spark Check

Check EEC-IV system for fault codes and repair if necessary. See Quick Test procedure in the appropriate TESTS W/CODES article in this section. If no fault codes are retrieved and vehicle is a no-start, using a Neon Bulb Spark Tester (D89P-6666-A), check for spark at each spark plug wire while cranking. If spark is consistent and equal at each spark plug (one spark per crankshaft revolution), go to appropriate ignition system in the appropriate SYSTEM/COMPONENT TESTS article in this section.

Scheme 2

Scheme 3

1. Using a high output spark tester, check for spark at coil wire. (Scheme 3) If spark is present, go to step 2). If spark is not present, remove distributor cap and crank engine to check for distributor rotation. If okay, check coil secondary wire resistance. Resistance should be no greater than 7000 ohms per foot.
2. With spark tester attached, cycle on and off 2-3 times. Spark should occur each time ignition is cycled. If spark is not present, go to step 3). If spark is present, inspect ignition components for wear or damage and service as necessary. Ensure distributor armature to sleeve roll pin is secure. Verify that Orange and Purple wires between distributor and ignition module ARE NOT CROSSED.
3. Turn ignition off. With ignition module connector attached, insert straight pin in Red wire. Ensure pin DOES NOT contact ground. Turn ignition on. Measure battery voltage. Measure voltage at straight pin. Straight pin voltage should be at least 90 percent of battery voltage. If not, check ignition switch and circuitry for wear or damage. Repair as necessary.
4. If battery voltage at straight pin is 12 volts, remove ignition coil and module connector. Inspect connector terminals and wiring. With an ohmmeter, measure resistance between ignition coil BAT terminal and ignition module harness connector Red wire. Resistance should be 0.8-1.6 ohms. If resistance is okay, replace ignition module. If not, replace ballast resistor.

Check EEC-IV system for fault codes and repair if necessary. See Quick Test procedure in the TESTS W/CODES article. If no fault codes are retrieved and vehicle is a no-start, use Neon Bulb Spark Tester (D89P-6666-A), check for spark at each spark plug wire while cranking. If spark is consistent and equal at each spark plug (one spark per crankshaft revolution), go to appropriate ignition system in the SYSTEM/COMPONENT TESTS article in this section.

Spark Output Check

1. 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 and should make a snapping noise as it jumps spark tester. If spark is present, go to step 3). If no spark is present, go to next step.
2. 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 as necessary and retest. If spark is not present, go to step 4).
3. 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 plug wire. If spark is now present at spark plugs and engine will not start, go to DIAGNOSTIC ROUTINE 201 (CRANKS NORMALLY BUT WON'T START) in the TESTS W/O CODES article in this section.
4. With ignition off, disconnect SPOUT connector at distributor. Connect a 12-volt test light to TFI module side of SPOUT connector. (Scheme 4)- (Scheme 6). Crank engine. If light blinks, the PIP sensor and TFI module are okay, use the appropriate coil testing procedure in the SYSTEM/COMPONENT TESTS article, or if the test light does not blink, see IGNITION SYSTEMS in the same SYSTEM/COMPONENT TESTS article in this section.

Scheme 4

Scheme 5

Scheme 6

IGNITION COIL RESISTANCE

IGNITION COIL RESISTANCE

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see the ADJUSTMENTS article in this section. Ensure all accessories are off and transmission is in Park or Neutral. Set parking brake. Disconnect automatic parking brake release (if equipped). Vehicle front wheels are in straight-ahead position and curb idle speed set to specification.

4-CYLINDER IGNITION TIMING

Note. Ignition timing is not adjustable on models with DIS or EDIS.

4-CYLINDER BASE IGNITION TIMING

4-CYLINDER IDLE SPEED

Idle speed is controlled by ECA and idle speed control air by-pass valve on all engines. If control system is operating properly, engine idle RPM is fixed and cannot be changed by standard adjustments. Many engines do not provide an RPM specification. A Scan tool must be used on these systems because the control strategy and idle speed specification is controlled by the ECA. See the appropriate ADJUSTMENTS article in this section.

Before performing idle speed adjustment procedure, complete a thorough basic inspection and self-test (KOEO, KOER, Continuous Memory self-tests) to confirm operation of sub-systems contributing to idle speed control problems. See the appropriate TESTS W/CODES article in this section.

V6 IGNITION TIMING

Note. Ignition timing is not adjustable on models with DIS or EDIS.

V6 BASE IGNITION TIMING

V6 IDLE SPEED

Idle speed is controlled by ECA and idle speed control air by-pass valve on all engines. If control system is operating properly, engine idle RPM is fixed and cannot be changed by standard adjustments. Many engines do not provide an RPM specification. A Scan tool must be used on these systems because the control strategy and idle speed specification is controlled by the ECA. See the appropriate ADJUSTMENTS article in this section.

Before performing idle speed adjustment procedure, complete a thorough basic inspection and self-test (KOEO, KOER, Continuous Memory self-tests) to confirm operation of sub-systems contributing to idle speed control problems. See the appropriate TESTS W/CODES article in this section.

V8 IGNITION TIMING

Note. Ignition timing is not adjustable on models with DIS or EDIS.

V8 BASE IGNITION TIMING

V8 IDLE SPEED

Idle speed is controlled by ECA and idle speed control air by-pass valve on all engines except 5.8L Crown Victoria and 5.8L Grand Marquis. If control system is operating properly, engine idle RPM is fixed and cannot be changed by standard adjustments. Many engines do not provide an RPM specification. A Scan tool must be used on these systems because the control strategy and idle speed specification is controlled by the ECA. See appropriate ADJUSTMENTS article.

Before performing idle speed adjustment procedure, complete a thorough basic inspection and self-test (KOEO, KOER, Continuous Memory self-tests) to confirm operation of sub-systems contributing to idle speed control problems. See appropriate TESTS W/CODES article in this section.

V8 BASIC IDLE RPM SPECIFICATIONS

IDLE MIXTURE ADJUSTMENT

Note. No idle mixture adjustments are possible on any models. See appropriate TESTS W/CODES article for diagnosis of incorrect idle mixture.

THROTTLE POSITION SENSOR (TPS) ADJUSTMENT

Note. Throttle Position Sensor (TPS) is not adjustable. Replace TPS if sensor is not within specification.

1.8L WITH MANUAL TRANSMISSION

1. Connect Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. Connect digital volt-ohmmeter positive lead to test pin No. 18. Connect negative lead to test pin No. 46. Continuity should be present with throttle at idle position.
2. Connect digital volt-ohmmeter positive lead to test pin No. 27. Connect negative lead to test pin No. 46. Continuity should be present with throttle at wide open position. If continuity is not as specified, perform KOEO self-test. See the appropriate TESTS W/CODES article in this section.

EXCEPT 1.8L WITH MANUAL TRANSMISSION

1. 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. Check voltmeter reading. See TPS VOLTAGE SPECIFICATIONS table.
2. 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, perform KOEO test. See the appropriate TESTS W/CODES article in this section.

TPS VOLTAGE SPECIFICATIONS (1)

SUMMARY

If no faults were found while performing the BASIC TESTING procedures in this article, proceed to the appropriate TESTS W/CODES article in this section. If no hard codes are found in, or if vehicle does not have a self-diagnostic system, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

See also:
• FUEL PRESSURE SPECIFICATIONS
• INDIVIDUAL INJECTOR RESISTANCE