Engine Control - Basic Diagnostic Procedures - Except S40 & V40: Other Volvo S80 I

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 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.

S70 & V70 - Non-Turbo

1. Connect fuel pressure gauge to Adapter (998-9725) to Attachment (999-5479), or equivalent. Connect adapter to fuel rail valve and ensure valve on adapter is closed. (Scheme 1)
2. Remove the cover from the integrated relay/fusebox in the engine compartment at the firewall. Remove fuel pump relay from central electrical unit located behind hood cowl. Fuel pump relay is No. 103. (Scheme 2) Put a jumper across relay base terminals 1 (blue/red wire, relay terminal 15) and 3 (pink wire, relay terminal 87).
3. Turn the ignition key to position II. Read off the line pressure from the pressure gauge.
4. Fuel pressure should be 43.5 psi (300 kPa).
5. Switch off the ignition Disconnect the cable between the terminals on the relay base. Reinstall the fuel pump relay.
6. The residual fuel line pressure must not fall below 29 psi (200 kPa) within 20 minutes of the fuel pump being shut-off.

C70, S70 & V70 - Turbo

Scheme 1

Scheme 2

Scheme 3

1. Connect fuel pressure gauge to Adapter (998-9725) to Attachment (999-5479), or equivalent. Connect adapter to fuel rail valve and ensure valve on adapter is closed. (Scheme 1)
2. Remove fuel pump relay from central electrical unit located behind hood cowl. Fuel pump relay is No. 103. (Scheme 2) Put a jumper across relay base terminals 1 and 3. (Scheme 3)
3. Switch ignition ON. Fuel pump should activate. Watch pressure gauge. Fuel pressure should be 54.4-57.3 psi (375-395 kPa). If pressure is OK, go to next step. If pressure is not as specified, repair as necessary.
4. Check residual fuel pressure. Turn ignition OFF. Install fuel pump relay. Keep fuel pressure gauge connected to fuel rail. Fuel pressure must not drop below 29 psi (200 kPa) within 20 minutes of pump shut-off. If pressure drops too quickly, locate and repair pressure leak.

S80

1. Attach fuel pressure gauge to fuel rail. (Scheme 1)
2. Start engine. Fuel pressure should be 54.4-57.3 psi (375-395 kPa). If pressure is OK, go to next step. If pressure is not as specified, repair as necessary.
3. Check residual fuel pressure. Turn ignition OFF. Install fuel pump relay. Keep fuel pressure gauge connected to fuel rail. Fuel pressure must not drop below 29 psi (200 kPa) within 20 minutes of pump shut-off. If pressure drops too quickly, locate and repair pressure leak.

Scheme 4

Scheme 5

CHECKING FUEL PRESSURE WHILE DRIVING VEHICLE

Note. Use foam padding or clean shop towels to protect vehicle interior and body.

Scheme 6

1. Connect Fuel Gauge (999-5011), or equivalent, to Adapter Hose (951-2614), or equivalent. (Scheme 6) CAUTION: Ensure that hose follows rubber intake plenum trim and exits engine bay at rear corner of hood. Fuel Gauge T-valve MUST be outside closed hood. Incorrect arrangement will cause vehicle damage.
2. Remove cap from fuel line fitting and attach Adapter Hose loosely. Place foam pad or shop towel between T-valve and mirror. Attach T-valve to left mirror using strap-ties.
3. Connect fuel drainage hose to T-valve to prevent fuel from spilling past T-valve directly onto vehicle.
4. Tighten Adapter hose fitting onto fuel rail. Turn ignition ON and wait for fuel gauge to indicate starting fuel pressure.
5. Start engine. Ensure that no more fuel will spill past T-valve and remove fuel drain hose.
6. Drive vehicle and read fuel pressure. Pressure should be 54.4-57.3 psi (375-395 kPa). Pressure should be stable at constant load and should fluctuate during acceleration or engine braking. If not as specified, locate and repair fuel pressure leak. If pressure is OK, go to next step.
7. Ignition OFF. Attach drain hose to T-valve. Remove strap-ties from fuel gauge and open vehicle hood. Place Gauge inside engine compartment to prevent spilling fuel on vehicle body during removal.
8. Place a container below fuel rail. Remove adapter hose fitting from fuel rail and wait for hose to finish draining before moving. When pressure checking equipment is removed, install cap onto fuel rail fitting.

IDLE SPEED & IGNITION TIMING

See IDLE SPEED & CO LEVEL and IGNITION TIMING tables. Idle speed is not adjustable.

IDLE SPEED & CO LEVEL (1)

IGNITION TIMING (DEGREES BTDC @ RPM)

SUMMARY

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