Honda Pilot: PGM-FI System Description - On-Board Snapshot

Overview

For an easy analysis of problems caused by engine stalls and starting problems, the powertrain control module (PCM) uses an on- board snapshot to record the operational conditions at the time of engine stalls and engine starting problems.

There are three types of on-board snapshots: the on-board snapshot when DTC is stored, the on-board snapshot when engine stalls, and the on-board snapshot when engine does not start.

The data of the on-board snapshots memorized by the PCM can be checked with the HDS.

Make sure to clear each type of on-board snapshots after checking it. PCM only memorizes their on-board snapshots when they are initially triggered.

Control

On-board snapshot when engine stalls:

The preconditions for recording an on-board snapshot when the engine stalls are shown below. When an engine stall occurs under these preconditions, the parameters related to the engine stall are stored in the PCM - for a time span extending for 9 seconds before the engine stall and 1 second after the engine stall - covering a total of 10 seconds.

The precondition is:

• After 5 seconds have elapsed after engine start (engine speed 500 rpm or higher) ( When an engine stalls within 5 seconds after the engine starts, the on-board snapshot is not saved in the memory area that records engine stalls. It is saved in the "Engine Does Not Start" memory area because the engine did not run for 5 seconds before stalling.)
• Engine speed at the time of an engine stall below 3,000 rpm
• After 1 drive cycle, after PCM reset, or battery terminal disconnection.
• Not during SCS short

*: In case of an engine stall for a vehicle with manual transmission at a vehicle speed of 3.1 mph (5 km/h) or lower, the on-board snapshot is not memorized.

On-board snapshot when engine does not start:

The three types of "engine is hard to start", "engine will not start", and "engine start but stalls immediately" are set for an on-board snapshot at the time of engine starting problems.

The preconditions for recording an on-board snapshot when engine does not start are as shown below, and when engine starting problems occur under these preconditions, the parameters related to the engine starting problems are memorized in the PCM.

The precondition is:

• After 1 drive cycle or after PCM reset or battery terminal disconnection.
• Not during SCS short

Timer for the evaluation of starting problems

The timer for evaluation of engine starting problems is variable and depends on the engine coolant temperature when the engine starts. The relation between the engine coolant temperature and the engine start time is shown below.

On-board snapshot of "engine is hard to start" and "engine will not start":

An on-board snapshot is taken when an engine does not start or when an engine is hard to start. The snapshot is taken when cranking (engine speed 500 rpm or lower) takes longer than the specified time (timer for the evaluation of starting problems: variable according to the conditions at the time of start). If it is determined that a starting problem exists, the parameters related to the starting problem (for 9 seconds before the evaluation of the starting problem and 1 second after the evaluation of a starting problem) are stored in the PCM, covering a total of 10 seconds.

On-board snapshot of "engine starts but stalls immediately":

An on-board snapshot is taken when an engine stall occurs within 5 seconds after the engine start, although the engine started (engine speed 500 rpm or higher) with cranking (engine speed 500 rpm or lower) within the specified time (timer for evaluation of starting problems: variable according to the conditions at the time of start). The parameters related to the stall after a complete combustion process for the 9 seconds before the engine stall and 1 second after the engine stall are stored in the PCM, covering a total of 10 seconds.

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