LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Plymouth >> 1981 >> Trailduster PD150, 5.2L Eng VIN R >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Electronic Fuel Control >> Testing >> Electronic Spark Control System Tests >> Spark Control Computer Spark Test
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Spark Control Computer Spark Test

  1. Warm engine to normal operating temperature. Disconnect carburetor switch or unground it by placing a piece of paper between curb idle adjusting screw and switch. Be sure coolant temperature sensor is connected and working properly.
  2. Remove and plug vacuum hose at vacuum transducer. Connect an auxiliary vacuum supply to vacuum transducer and apply 16 in. Hg. 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. 
    NOTE: The 3.7L engine is equipped with an accumulator. The carburetor switch MUST be ungrounded for 30 seconds before checking specified spark advance schedule.
    Spark Advance Test Specifications(1)

    Computer Part No. (2)Spark Advance
    4145431 20°
    4145457 34°
    4145466 34°
    4145788 34°
    4145817 20°
    4145850 34°
    (1) Engine speed 2000 RPM and 16 in. Hg vacuum applied.
    (2) All readings ±4°. If amount of advance differs here from emission control label, use label as accurate listing.
  3. If computer fails to obtain settings, replace computer.
scientia non olet · About LEMON Manuals