Starting, Cold Engine
SYSTEM FAILURE SYMPTOMS: Extreme difficulty in starting a cold engine.
TEST
A. COLD START INJECTOR CIRCUIT
1. Unplug the fuel pump relay (position G, main fuse panel) and hot start pulse relay (position F, emissions relay panel).
2. Check the cold start injector ground circuit by connecting a test light between 12v and the GREEN AND WHITE wires on the back of the cold start injector plug. If the ground circuit is complete, the test light will be brightly lit.
NOTE: Coolant temperature must drop below 65~F/18~C in order for the thermal switch on the front of the thermostat housing to close, the switch will then reopen when the temperature increases above 77~F/25~C. During warm weather or on cars tested in a heated shop, the cold start injector ground circuit will not be operable. If no fault can be found in the rest of the system, verify thermal switch operation by removing it from the thermostat housing, cooling it below 65~F and using an ohm meter to confirm that the contacts are closed.
3. Verify proper operation of the thermo-time switch by connecting a test light between 12v and the GREEN wire on the thermo-time switch plug. If the coolant temperature is below 113~F/45~C, the test light should be brightly lit. Engage the starter for a short period, the light should go out after a few seconds of cranking, indicating the small heating element in the thermo-time switch has opened the ground circuit. Low wattage test lights will glow dimly after the ground circuit contacts have opened. Don't confuse this with a full intensity closed circuit reading.
4. Connect the test light from ground to the BROWN wire on the cold start injector. You should have power whenever the starter motor is engaged.
5. If there is no electrical fault, but a cold start problem persists, you can verify cold start injector function by removing the injector and checking the spray pattern. Observe the following steps:
a. If practical, move the car outside, away from sparks and flame and have a fire extinguisher handy. YOU ARE DEALING WITH AN EXTREMELY EXPLOSIVE MIXTURE!
b. Simulate a cold engine by placing a jumper wire from the WHITE thermal switch wire to ground.
c. Disable the ignition system by disconnecting the primary harness plug from the base of the distributor.
d. Jump the fuel pump relay socket pins 30 and 87 to energize the pump.
e. Remove the cold start injector from the intake manifold, aim it into a container and crank the engine over for a few seconds. The injector should spray a finely atomized mist of fuel and close without leakage as soon as you stop cranking.
B. LAMBDA TRANSIENT ENRICHMENT CIRCUIT
1. Reinstall all relays and reconnect the distributor primary lead.
2. Connect the Lambda pulse ratio meter, leave on throughout the test.
NOTE: The small Saab pulse ratio meters that connect directly to the two wire test plug on the car draw their power from a circuit which is dead during cranking. The easiest way to provide power to the meter for this test is to place a jumper between the two large pins (3 & 4) of the ignition lock relay socket, (position E of the main fuse panel).
3. Engage the starter and watch the Lambda meter. The pulse ratio should lock on 92% +/- 10% during cranking and for three seconds after the engine starts.
4. If inoperative, check at the transient enrichment relay socket.
a. Test light connected to 12 volts
Pin 31 Ground at all times TRK Ground with closed throttle (manual transmission only)
b. Test light connected to ground
Pin 50 12v during cranking
TIP 12v pulse on acceleration
87 12v when the engine is running
11 Pulse ratio of 92% +/- 10% when the pin is grounded
c. Ohm meter or other continuity tester
Pin X2 Continuity with X2 of the decel relay TKK Continuity with the WHITE wire on the thermal switch, also check continuity from the thermal switch GREEN wire to the thermo time switch GREEN wire