Diagnostic Aids

Check TP sensor for inaccuracy, binding or sticking in wide open position, or internal opens or shorts. Check for low fuel level or fuel contamination. Check for engine mechanical problems i.e., low compression (timing chain failure). Check for skewed MAP sensor. The MAP sensor value should change when cranking engine. Compare any questionable barometer readings with that of a known-good vehicle.

Check PCM ground circuits. The PCM ground circuits will only cause a problem if all grounds are not making a good connection. If a PCM ground problem is suspected, the most probable place to inspect is where grounds meet at engine block.

A cold engine that has not been started should display ECT and IAT temperatures that are relatively close to each other.

Intermittent concerns may be caused by several conditions i.e., poor connections, rubbed through wire insulation and broken wires inside their insulation. Check for poor connections or damaged harnesses. Check PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connections and damaged harnesses.