Initial Inspection and Diagnostic Overview

SYMPTOM DIAGNOSIS
The Powertrain Control Module (PCM) uses information from the Manifold Absolute Pressure (MAP) sensor and Engine Coolant Temperature (ECT) sensors in addition to RPM to calculate spark advance as follows:
- Low MAP output voltage = More spark advance.
- Cold engine = More spark advance.
- High MAP output voltage = Less spark advance.
- Hot engine = Less spark advance.
Therefore, detonation could be caused by low MAP output or high resistance in the coolant sensor circuit.
Poor performance could be caused by high MAP output or low resistance in the coolant sensor circuit.
Whenever the engine cranks but will not run or immediately stalls, Table A-3 must be used to determine if the fault is in the Electronic Ignition (EI) system or the fuel system.