Engine Controls - Basic Testing Dodge Dynasty I

INTRODUCTION

The following diagnostic steps can help you prevent overlooking a simple problem. This is also the place to start diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is to verify that the problem exists. This may be accomplished by test driving the vehicle under the conditions during which the problem reportedly occurs.

Prior to entering self-diagnostics, a careful and complete inspection of several systems is required. Most driveability or no-start problems are not related to computerized engine control systems, but are in fact simple mechanical, electrical, fuel or vacuum related faults. Most engine control problems are the result of mechanical breakdowns, poor electrical connections or damaged or misrouted vacuum hoses.

Before considering the computer system as a possible cause of problems, ignition high tension wires, fuel supply, electrical connections and vacuum hoses should be checked. Failure to do so may result in improper diagnosis or lost diagnostic time.

Note. All voltage tests should be performed with a Digital Volt- Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in testing procedures.

VISUAL INSPECTION

Perform a visual inspection of all electrical wiring. Look for chafed, stretched, cut or pinched wiring. Inspect electrical connectors and connections for tight fit and corrosion. Repair as necessary. Inspect all vacuum hoses for proper routing, cuts or pinches. If necessary, see VACUUM DIAGRAMS article to verify routing and connections. Repair as necessary. Inspect air induction system for possible vacuum leaks.

COMPRESSION

Engine mechanical condition can be checked using a compression gauge, vacuum gauge, or an engine analyzer capable of performing a relative compression test. See engine analyzer instruction manual for availability and description of relative compression feature.

EXHAUST SYSTEM BACKPRESSURE

The exhaust system can be checked with a vacuum gauge or a pressure gauge. Remove O2 sensor or air injection check valve (if equipped). Connect a 1-10 psi 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 it to intake manifold vacuum 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.

FUEL PRESSURE

Basic diagnosis of fuel system should begin with determining fuel system pressure.

FUEL PRESSURE RELEASE

1. Fuel pressure must be fully released before opening fuel system or removing any fuel carrying components. To release pressure in tank, open fuel tank cap slowly.
2. To release remaining pressure in system, disconnect injector wiring harness. Using jumper wire, connect injector harness ground terminal No. 1 to ground. Connect injector harness positive terminal No. 2 to positive battery terminal with second jumper wire. (Scheme 1)or (Scheme 2).
3. DO NOT keep injector connector to positive battery terminal for longer than 5 seconds. Remove jumper wires. Fuel injection system can now be opened and fuel carrying components removed as pressure is fully released.

Scheme 1

Scheme 2

Note. Perform fuel pump test with fuel tank at least half full. Before disconnecting a fuel line during testing, repeat fuel pressure release procedure.

TBI FUEL PUMP TEST

1. Release fuel pressure. See «FUEL PRESSURE RELEASE»(/dodge/dynasty/i-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing__fuel-pressure-release) in this article. Disconnect 5/16" fuel supply hose. Connect fuel system pressure Gauge (C-4799-A) between fuel supply hose and engine fuel line.
2. Turn ignition on. Using DRB-II (C-4805), activate fuel pump. See «FUEL PUMP PRESSURE SPECIFICATIONS»(/dodge/dynasty/i-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing) table in this article. If fuel pump pressure is at specification, fuel system is functioning properly.
3. If fuel pressure is not to specification, record pressure. Install fuel pressure gauge in fuel supply line at rear of vehicle between fuel tank and fuel filter.
4. Using DRB-II, activate fuel pump. See FUEL PUMP PRESSURE SPECIFICATIONS table in this article. Record pressure reading. If fuel pressure is 5 psi (.4 kg/cm 2 ) higher than first pressure reading, replace fuel filter.
5. If no change in pressure reading is observed, gently squeeze fuel return hose. If fuel pressure increases, replace fuel pressure regulator. If no change in fuel pressure is observed, problem is plugged fuel pump filter sock or defective fuel pump.
6. If fuel pressure is more than specification, remove fuel return hose at rear of vehicle. Connect an extension hose to return hose. Place hose in an approved container with at least a 2 gallon capacity.
7. Using DRB-II, activate fuel pump. If fuel pressure is now within specification, check in-tank return fuel hose for kinking. Replace fuel tank assembly if in-tank reservoir check valve or aspirator jet is plugged.
8. If fuel pressure is still more than specification, remove fuel return hose from throttle body. Connect a substitute hose to throttle body return nipple. Place other end of hose in an approved container.
9. Using DRB-II, activate fuel pump. If fuel pressure is at specification, check for a restricted fuel return line between throttle body and fuel tank. If no change was observed, replace fuel pressure regulator.

Note. Perform fuel pump test with fuel tank at least half full. Before disconnecting a fuel line during testing, repeat fuel pressure release procedure.

4-CYLINDER PFI FUEL PUMP TEST

1. Release fuel pressure. See FUEL PRESSURE RELEASE in this article. Remove cap from service valve on fuel rail. Connect fuel system pressure Gauge (C-4799-A) to service valve.
2. Turn ignition on. Using DRB-II, activate fuel pump. See «FUEL PUMP PRESSURE SPECIFICATIONS»(/dodge/dynasty/i-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing) table in this article. If fuel pump pressure is at specification, fuel system is functioning properly.
3. If fuel pressure is not to specification, record pressure and remove gauge. Using DRB-II, activate fuel pump. Ensure no fuel leaks from service valve. Install cap on service valve.
4. If fuel pressure is not to specification, install pressure gauge in fuel supply line between fuel tank and fuel filter at rear of vehicle. Using DRB-II, activate fuel pump.
5. Record pressure reading. If fuel pressure is 5 psi (.4 kg/cm 2 ) higher than first pressure reading, replace fuel filter. If no change in pressure reading is observed, gently squeeze fuel return hose.
6. If fuel pressure increases, replace fuel pressure regulator. If no change in fuel pressure is observed, problem is plugged fuel pump filter sock or defective fuel pump.
7. If fuel pressure is more than specification, remove fuel return hose at rear of vehicle. Connect an extension hose to return hose. Place hose in an approved container with at least a 2 gallon capacity.
8. Using DRB-II, activate fuel pump. If fuel pressure is now within specification, check in-tank return fuel hose for kinking. Replace fuel tank assembly if in-tank reservoir check valve or aspirator jet is plugged.
9. If fuel pressure is still more than specification, remove fuel return hose from pressure regulator. Connect a substitute hose to fuel pressure regulator. Place other end of hose in an approved container.
10. Using DRB-II, activate fuel pump. If fuel pressure is at specification, check for a restricted fuel return line. If no change was observed, replace fuel pressure regulator.

Note. Perform fuel pump test with fuel tank at least half full. Before disconnecting a fuel line during testing, repeat fuel pressure release procedure.

3.0L FUEL PUMP TEST

1. Release fuel pressure. See «FUEL PRESSURE RELEASE»(/dodge/dynasty/i-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing__fuel-pressure-release) in this article. Remove cap from service valve on fuel rail. Connect fuel system pressure Gauge (C-4799-A) to service valve.
2. Turn ignition on. Using DRB-II (C-4805), activate fuel pump. See «FUEL PUMP PRESSURE SPECIFICATIONS»(/dodge/dynasty/i-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing) in this article. If fuel pump pressure is at specification, fuel system is functioning properly.
3. If fuel pressure is not to specification, record pressure and remove gauge. Using DRB-II, activate fuel pump. Ensure no fuel leaks from service valve. Install cap on service valve.
4. If fuel pressure is not to specification, install pressure gauge in fuel supply line between fuel tank and fuel filter at rear of vehicle. Using DRB-II, activate fuel pump.
5. Record pressure reading. If fuel pressure is 5 psi (.4 kg/cm 2 ) higher than first pressure reading, replace fuel filter. If no change in pressure reading is observed, gently squeeze fuel return hose.
6. If fuel pressure increases, replace fuel pressure regulator. If no change in fuel pressure is observed, problem is plugged fuel pump filter sock or defective fuel pump.
7. If fuel pressure is more than specification, remove fuel return hose at rear of vehicle. Connect an extension hose to return hose. Place hose in an approved container with at least a 2 gallon capacity.
8. Using DRB-II, activate fuel pump. If fuel pressure is now within specification, check in-tank return fuel hose for kinking. Replace fuel tank assembly if in-tank reservoir check valve or aspirator jet is plugged.
9. If fuel pressure is still more than specification, remove fuel return hose from pressure regulator. Connect a substitute hose to fuel pressure regulator. Place other end of hose in an approved container.
10. Using DRB-II, activate fuel pump. If fuel pressure is at specification, check for a restricted fuel return line. If no change was observed, replace fuel pressure regulator.

3.3L FUEL PUMP TEST

1. Release fuel pressure. See «FUEL PRESSURE RELEASE»(/dodge/dynasty/i-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing__fuel-pressure-release) in this article. Remove cap from service valve on fuel rail. Connect fuel system pressure Gauge (C-4799-A) to service valve.
2. Turn ignition on. Using DRB-II (C-4805), activate fuel pump. See «FUEL PUMP PRESSURE SPECIFICATIONS»(/dodge/dynasty/i-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing) in this article. If fuel pump pressure is at specification, fuel system is functioning properly.
3. If fuel pressure is not to specification, record pressure and remove gauge. Using DRB-II, activate fuel pump. Ensure no fuel leaks from service valve. Install cap on service valve.
4. If fuel pressure is not to specification, install pressure gauge in fuel supply line between fuel tank and fuel filter at rear of vehicle. Using DRB-II, activate fuel pump.
5. Record pressure reading. If fuel pressure is 5 psi (.4 kg/cm 2 ) higher than first pressure reading, replace fuel filter. If no change in pressure reading is observed, gently squeeze fuel return hose.
6. If fuel pressure increases, replace fuel pressure regulator. If no change in fuel pressure is observed, problem is plugged fuel pump filter sock or defective fuel pump.
7. If fuel pressure is more than specification, remove fuel return hose at rear of vehicle. Connect an extension hose to return hose. Place hose in an approved container with at least a 2 gallon capacity.
8. Using DRB-II, activate fuel pump. If fuel pressure is now within specification, check in-tank return fuel hose for kinking. Replace fuel tank assembly if in-tank reservoir check valve or aspirator jet is plugged.
9. If fuel pressure is still more than specification, remove fuel return hose from pressure regulator. Connect a substitute hose to fuel pressure regulator. Place other end of hose in an approved container.
10. Using DRB-II, activate fuel pump. If fuel pressure is at specification, check for a restricted fuel return line. If no change was observed, replace fuel pressure regulator.

FUEL PUMP PRESSURE SPECIFICATIONS

FUEL PUMP PRESSURE SPECIFICATIONS

* PLEASE READ THIS FIRST *

Note. If ASD relay is suspected of causing a fuel or ignition system malfunction, it will be necessary to use Diagnostic Readout Box (DRB-II) to diagnose ASD relay. See appropriate TESTS W/CODES article.

ALL EXCEPT 3.3L

When distributor signal is not present with ignition switch in RUN position, ASD relay turns off power to electric fuel pump, fuel injectors, ignition coil and O2 sensor heating element.

3.3L

When there is no cam or crankshaft sensor signal with ignition switch in RUN position, ASD relay turns power off to electric fuel pump, fuel injectors, ignition coil and O2 sensor heating element.

TESTING SPARK AT COIL 2.2L, 2.5L & 3.0L

1. Remove coil wire from distributor cap. Hold end of cable approximately 1/4" from ground. Crank engine and check for spark from coil wire. If spark is present at coil wire, spark must be constant.
2. If spark is present and constant, continue cranking engine. Slowly move coil wire away from ground. As coil wire is moved away from ground, check for arching at coil tower. If arching at coil tower is present, replace coil.
3. If spark is good and no arching is present, secondary ignition system is producing necessary voltage. Ensure spark is getting to spark plugs by checking condition of rotor, cap, spark plug wires and spark plugs. Repair or replace as necessary. If ignition system components are in good condition, ignition system is okay.

TESTING SPARK AT COIL 3.3L

1. This system has 3 independent coils. These coils must be tested separately. Remove spark plug wire from No. 2 spark plug. Insert a clean screwdriver into spark plug boot.
2. Hold screwdriver approximately 1/4" from ground. Crank engine and watch for spark between screwdriver and ground. Repeat this test for No. 4 and 6 spark plug wires.
3. If no spark was present on any cylinder tested, go to FAILURE TO START TEST. If one or more cylinders has weak or no spark, go to next step.
4. Remove spark plug wires one at a time. Using an ohmmeter, measure resistance of each spark plug wire. Resistance should be 3000-12,000 ohms per foot. Replace spark plug wire(s) not within specification.
5. Measure resistance on primary side of each coil. Resistance should be.5-.7 ohm. Measure resistance between B+ terminal of ignition coil connector and corresponding cylinders. (Scheme 3) Replace coil if resistance is not within specification.
6. Remove spark plug wires from coil one at a time. Measure secondary resistance of ignition coil between grouped cylinders and coil towers. Resistance should be 7000-14,000 ohms. Replace coil if resistance is not within specification.

Scheme 3

FAILURE TO START TEST 2.2L, 2.5L & 3.0L

Note. Perform TESTING SPARK AT COIL before proceeding with test.

1. Ensure sufficient battery voltage is available to operate cranking and ignition systems. Crank engine for 5 seconds while monitoring voltage at coil positive terminal.
2. If voltage remains near zero during entire period of cranking, see appropriate SELF-DIAGNOSTICS article to check SBEC and ASD relay. If voltage is near battery voltage and drops to zero after 1-2 seconds of cranking, see appropriate SELF-DIAGNOSTICS article to check distributor pick-up circuit to SBEC.
3. If voltage remains near battery voltage during entire 5 seconds, turn ignition off. Disconnect SBEC 60-pin connector. Check 60-pin connector for loose terminals (push-outs).
4. Remove positive lead from coil. Connect a jumper wire between battery positive terminal and coil positive terminal. Using a specially constructed jumper wire, momentarily ground SBEC harness connector terminal No. 19. (Scheme 4) Spark should be generated when ground connection is disconnected. (Scheme 5)
5. If spark is generated, replace SBEC. If no spark was generated, use special jumper wire directly on coil negative terminal. If spark is produced, repair wiring harness for an open circuit. If no spark is produced, replace ignition coil.

Scheme 4

Scheme 5

FAILURE TO START TEST 3.3L

1. Ensure sufficient battery voltage is available to operate cranking and ignition systems. Connect voltmeter between B+ wiring harness coil connector and ground.
2. Crank engine for 5 seconds while monitoring voltage at B+ terminal. If voltage remains near zero during entire period of cranking, see appropriate SELF-DIAGNOSTICS article to check SBEC and ASD relay.
3. If voltage is near battery voltage and drops to zero after 1-2 seconds of cranking, see appropriate SELF-DIAGNOSTICS article to check cam and crank sensor circuits to SBEC.
4. If voltage remains near battery voltage during entire 5 seconds, turn ignition off. Disconnect SBEC 60-pin connector. Check 60-pin connector for loose terminals (push-outs).

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ON-VEHICLE ADJUSTMENTS article.

Note. Curb idle speed is controlled by SBEC and not adjustable.

IGNITION TIMING (Degrees BTDC @ RPM)

SUMMARY

If no faults were found while performing BASIC TESTING proceed to appropriate G - TESTING W/CODES article. If no hard codes are found in self-diagnostics, proceed to H - TESTING W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.), or intermittent diagnostic procedures.

See also:
• FUEL PRESSURE RELEASE
• FUEL PUMP PRESSURE SPECIFICATIONS