keithwalton
Well-Known Member
It would be interesting to see an OBD log during a cold start to see what changes when it transitions out of high idle.
Data of interest would be cam phaser positions, exhaust gas temperature, oxygen sensor temperature, ignition timing. cat temp etc.
For reference on a cold start engines will be in. 'open loop' mode using last known good settings until the oxygen sensors are hot enough to give an accurate reading.
In order to reduce emissions they will also be attempting to 'light off' the catalytic converter (get it into it's operating temperature range) as fast as possible.
Which is usually done by altering the exhaust cam timing and ignition to the point combustion is still occurring / only just ending as the exhaust valve opens.
Rapid heatup of the cereamic in cats can tick, (same on cool down) but would be interesting if the tick is synced to combustion events or just rapid ticking.
Data of interest would be cam phaser positions, exhaust gas temperature, oxygen sensor temperature, ignition timing. cat temp etc.
For reference on a cold start engines will be in. 'open loop' mode using last known good settings until the oxygen sensors are hot enough to give an accurate reading.
In order to reduce emissions they will also be attempting to 'light off' the catalytic converter (get it into it's operating temperature range) as fast as possible.
Which is usually done by altering the exhaust cam timing and ignition to the point combustion is still occurring / only just ending as the exhaust valve opens.
Rapid heatup of the cereamic in cats can tick, (same on cool down) but would be interesting if the tick is synced to combustion events or just rapid ticking.
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