Dr-20A: Inspection Of Mechanical System & Components

The systems controlled by the Electronic Control Unit (ECU) are functioning as intended. This indicates that a mechanical system malfunction is the cause of the driveability problem. Check if any TECHNICAL SERVICE BULLETINS (TSBs) relate to this driveability problem. The following areas should also be examined:

• Check ignition timing.
• Check engine vacuum.
• Check engine compression.
• Check valve timing.
• Check for exhaust system restriction.
• Check torque converter stall speed.
• Check for fuel contamination.
• Check secondary ignition circuit for abnormal scope pattern.