Spark Control Computer Spark Test
NOTE:
Ensure basic timing is properly set before performing test.
- Warm engine to normal operating temperature. Connect adjustable timing light or magnetic timing probe to engine. Unground carburetor switch by placing a thin piece of cardboard between curb idle adjusting screw and switch or make sure curb idle adjusting screw does not contact switch. Be sure coolant temperature sensor/switch is connected and working properly.
- Remove and plug vacuum hose at vacuum transducer. Connect an auxiliary vacuum supply to vacuum transducer and apply 10 in. Hg (16 in. Hg on 5.2L engine). Increase engine speed to 2000 RPM and wait 1 minute before checking specifications. Advance specifications are in addition to basic advance. See Spark Advance Test Specifications table.
- If computer fails to obtain settings, replace computer.
NOTE:
The 3.7L engine is equipped with an accumulator (timer). The carburetor switch MUST be ungrounded until accumulator times out before checking specified spark advance schedule.
SPARK ADVANCE TEST SPECIFICATIONS (PICKUP)
| Application |
Computer No. |
Spark Advance |
| 3.7L M/T |
| Federal W/Overdrive |
4289304 |
39° |
| California |
4289324 |
20° |
| 3.7L A/T |
| Federal |
4289308 |
43° |
| California |
4289326 |
21° |
| 5.2L M/T |
| California |
4289075 |
44° |
| High Altitude |
4289310 |
42° |
| 5.2L A/T |
| California |
4289077 |
42° |
| High Altitude |
4289310 |
42° |
SPARK ADVANCE TEST SPECIFICATIONS (VAN)
| Application |
Computer No. |
Spark Advance |
| 3.7L M/T |
| Federal W/Overdrive |
4289351 |
39° |
| California |
4289356 |
20° |
| 3.7L A/T |
| Federal |
4289352 |
43° |
| California |
4289357 |
21° |
| 5.2L M/T |
| California |
4289086 |
44° |
| High Altitude |
4289364 |
42° |
| 5.2L A/T |
| California |
4289094 |
42° |
| High Altitude |
4289364 |
42° |