Engine Controls - Basic Testing - 2.5L V6: Other Saab 900 II

Compression

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

Measure engine compression at normal operating temperature with all spark plugs removed. To prevent damage to catalytic converter, test quickly and only if necessary.

Note. Compression pressures are not specified by manufacturer.

COMPRESSION RATIO

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 1 3/4 - 2 psi, exhaust system or catalytic converter is plugged.

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 steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction.

FUEL SYSTEM

FUEL PRESSURE

Begin basic diagnosis of fuel system by measuring system pressure.

1. Turn ignition off. Disconnect banjo coupling at inlet to fuel injection manifold. Connect a fuel pressure gauge, using existing seals. Hang pressure gauge vertically.
2. Remove fuse No. 32 (15-amp). Connect a fused jumper lead between battery voltage and load side slot of fuse No. 32. This will provide current to fuel pump. Turn ignition on.
3. Fuel pressure should increase to about 43 psi (3.0 kg/cm 2 ). If fuel pressure is too high, go to next step. If fuel pressure is too low, go to step 5).
4. Turn ignition off. Disconnect fuel return line from pressure regulator. Blow through line. If line is open, pressure regulator is defective and should be replaced. If line is blocked, remove blockage or replace with a new return line. Inspect one-way valve at tank, and retest system.
5. Check fuel level; DO NOT rely on fuel gauge. Inspect for fuel system leaks. Test fuel pressure regulator. See «FUEL PRESSURE REGULATOR»(ref-15452-S42140121362000122900000) .

Fuel Pressure Regulator

1. If fuel pressure gauge is already attached, go to next step. If gauge is not attached, disconnect banjo coupling at inlet to fuel injection manifold. Connect fuel pressure gauge at this point, using existing seals. Hang pressure gauge vertically.
2. Connect Pressure Gauge (83-93-514 ) and "Y" connection to vacuum port of fuel pressure regulator. Hang gauge vertically. Connect pressure/vacuum tester to "Y" connection.
3. Remove fuse No. 32 (15-amp). Connect a fused jumper lead between battery voltage and load side slot of fuse No. 32. This will provide current to fuel pump. Turn ignition on.
4. Fuel pressure should increase to about 43 psi (3.0 kg/cm 2 ). Install vacuum pump to "Y" connection. Fuel pressure should be about 43 psi (3.0 kg/cm 2 ). Use vacuum pump to reduce system pressures as specified in «REGULATED FUEL PRESSURE (VACUUM APPLIED)»(ref-15452-S33160041782000122900000) table. Compare fuel pressure to specification. Disconnect vacuum pump. REGULATED FUEL PRESSURE (VACUUM APPLIED) Applied Vacuum In. Hg Fuel Pressure psi (kg/cm 2 ) 0 43 (3.0) 5 40.5 (2.9) 10 38 (2.7) 15 35.5 (2.5)
5. Turn ignition on to operate fuel pump. Verify fuel pressure is 43 psi (3.0 (3.0 kg/cm 2 ). Turn ignition off. Pressure should drop 1.4-2.8 psi (0.1-0.2 kg/cm 2 ) and then hold steady for at least 10 minutes.
6. If pressure drop is more than specified, inspect for leakage in pressure regulator and fuel pump non-return valve.

Fuel Pump Delivery Pressure

1. Turn ignition off. Disconnect banjo coupling at inlet to fuel injection manifold. Connect fuel pressure gauge, using existing seals. Hang pressure gauge vertically. Turn ignition on. Pinch off fuel return line. Measure fuel pressure. When line is plugged, fuel pressure should increase immediately. CAUTION: DO NOT allow pressure to exceed 82 psi (5.8 kg/cm 2 ).
2. If fuel pressure does not increase, inspect for following faults: Less than 11.5 volts across fuel pump terminals. Obstructed fuel lines. Clogged fuel filter. Fuel filter installed backward. Defective relief valve in fuel pump. NOTE: If fuel filter has been installed backward, it must be replaced.
3. After measuring fuel pump pressure, turn ignition off. Leave pressure gauge connected. Go to «FUEL PUMP FLOW»(ref-15452-S00602625892000122900000) .

Fuel Pump Flow

1. Turn ignition off. Disconnect fuel return line at pressure regulator. Connect a section of test hose to return line at pressure regulator. Place other end of test hose in 2-quart (approximate) graduated container.
2. Activate fuel pump by turning ignition on. Run fuel pump for 30 seconds. Measure volume of fuel flow and fuel pressure drop. Minimum acceptable volume is 1.9 pts. (0.9L); maximum allowed fuel pressure drop is 2.8 psi (0.2 kg/cm 2 ). If fuel volume or pressure drop does not meet specification, replace fuel pressure regulator.

MOTRONIC IGNITION SYSTEM

Information not available at time of publication.

PROGRAMMING ECM

Note. If power supply to Electronic Control Module (ECM) has been interrupted, system must be reprogrammed.

Drive vehicle for 10 minutes with engine at normal operating temperature.

IDLE SPEED & IGNITION TIMING

For idle speed adjustment, see ADJUSTMENTS - 2.5L V6 article. Vehicle is equipped with a Distributorless Ignition System (DIS). Ignition timing is controlled by the Electronic Control Module (ECM) and is not adjustable.

SUMMARY

If no faults were found while performing steps in BASIC TESTING , proceed to TESTS W/ CODES 2.5L V6 article. If no hard codes are found in self-diagnostics, (if vehicle has self-diagnostic system) proceed to TESTS W/O CODES - 2.5L V6 article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

Wiring Diagram (1 Of 3). Scheme 36

Wiring Diagram (2 Of 3). Scheme 37

Wiring Diagram (3 Of 3). Scheme 38