Engine Controls - Basic Testing: Other Volvo 960 I рестайлинг

Compression

Check engine mechanical condition using a compression gauge, vacuum gauge or engine analyzer. See engine analyzer manual for specific instructions.

COMPRESSION SPECIFICATIONS

Exhaust System Backpressure

1. Exhaust system can be checked using a vacuum or pressure gauge. Remove oxygen sensor or air injection check valve (if equipped).
2. Connect a 1-10 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.
3. If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steadily. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction.

FUEL SYSTEM

Fuel Pressure

1. Before disconnecting, cover fuel line connector using shop towel to absorb any fuel spray. Connect Fuel Pressure Gauge (5011 ) between fuel line and fuel rail. Seal free end of hose using Plug (5266 ) or use Fuel Drainage Unit (981 2270, 2273 and 2282 ).
2. Remove fuel injection fuses No. 30 and 31. (Scheme 1) Connect jumper wire between fuse terminals No. 30 and 31.
3. Turn ignition on. Fuel pump should start. Fuel filler cover can be removed to determine whether main pump is operating. Fuel pressure should be about 43.5 psi (3.06 kg/cm 2 ). If pressure is too low, pinch return hose by hand and check whether pressure rises. DO NOT allow pressure to exceed 86 psi (6 kg/cm 2 ).
4. If pressure rises rapidly, pump and lines are okay. Replace pressure regulator and recheck line pressure. If pressure rises slowly, fuel filter, fuel pump strainer or fuel lines are blocked. If pressure does not rise, fuel pump is probably faulty.
5. If pressure is too high, remove jumper wire between relay or fuse terminals. Remove return hose from pressure regulator. Blow in pipe. Remove vacuum hose from pressure regulator. Blow in pipe. If both hoses are open, pressure regulator is defective. Replace regulator and recheck pressure.

Scheme 1

Note. ECU terminal identifications are marked on unit or connector.

Fuel Pump Circuit

If fuel pumps do not operate with ignition on, connect Breakout Box (999-3070 ) to ECU. (Scheme 2) Connect voltmeter between terminals No. 3 and 19. Voltmeter should indicate battery voltage. If battery voltage is not present, check wiring and voltage supply to pump relay. If voltage is present, check wiring and voltage supply to fuel pump.

Scheme 2

Determining Whether Fault Is Fuel Or Ignition

Using a volt-meter, check voltage at injectors when engine is hot. If voltage is about 250-400 millivolts, fault is in ignition system and/or an injector is blocked.

Checking Ground Connections

1. Turn ignition off. Remove fuse No. 24. Connect Breakout Box (999-3070) to ECU. (Scheme 2) Connect ohmmeter between ground and terminals No. 19, 24, 26, 30 and 48. Resistance should be about zero ohms on all measurements.
2. Check power unit ground connections under each power unit. Connect an ohmmeter between ground and terminal No. 4 on front power unit connector and then on rear power unit connector.
3. Ohmmeter should indicate about zero ohms in both cases. If ohmmeter does not indicate about zero ohms in both cases, check connectors and wiring.

Voltage Supply To Ignition Coils

Turn ignition on. Connect volt-meter between ground and test terminal at rear of engine. (Scheme 3) Voltmeter should show battery voltage. If battery voltage is not present, check relay, wiring and connectors.

Scheme 3

Cylinder Miss

Idle engine. Disconnect and reconnect one injector connector at a time. If engine speed drops when connector is disconnected, cylinder is okay.

Checking Firing Pulse At Ignition Coil

1. Make an adapter to fit between ignition coil connector and test diode (999-5280 ). Connect test diode. (Scheme 4)
2. Start engine. Diode should flash if signal is present. If signal is present, go to step 5). If no signal is present, connect voltmeter between ground and control unit terminals connected to each ignition coil.
3. If voltage is about 3.5 volts, an open circuit is present between control unit and ignition coil. If voltmeter indicates 60-100 millivolts, connect diode tester with positive side connected to control unit terminal for cylinder to be checked and to terminal No. 1 on corresponding ignition coil connector. Check components with leads reversed.
4. Connect diode tester with positive side connected to ground and to terminal No. 1 on ignition coil connector. Check components with leads reversed. If fault is present, check wiring.
5. Remove coil and plug. Install another plug in cylinder. Install original plug in ignition coil. Start engine and check for spark. If no spark is present, check whether coil or plug is faulty. Install plug in another coil. If spark is present, replace original coil. If no spark is present, replace spark plug.

Scheme 4

IDLE SPEED & IGNITION TIMING

Note. Idle speed and ignition timing are not adjustable. See the IDLE SPEED & CO LEVEL and IGNITION TIMING tables for specifications.

IDLE SPEED & CO LEVEL (1)

IGNITION TIMING (Degrees BTDC @ RPM)

SUMMARY

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