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Halteh Elite Coolant Temp Bias

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In the Hlatech Elite series, under sensor properties, there's a table called Coolant Temp Bias. As I understand it, it allows the calculated air temperature to be influenced by the coolant temperature. The base table from Haltech shows most of the bias to be trimmed in at idle, to cruise rpm.

My question is why would you need this? If the engine is idling or cruising along, and the ATS is reporting the temperature where the MAP is being taken, and your air temp correction table is set up correctly (or even using the Auto V.E. Air Temp Compensation), why would you want the coolant temperature influencing the air temp calculation?

I'm sure that there's a legitimate reason it's there, I just don't know what it is... :-)

I can only assume this is to compensates for throttle bodies that have coolant pass through them to heat up the intake charge. So, even though the air temp sensor might be ready the charge just before the throttle body, there will be some heat being transfer to the air from the coolant system.

At idle and low engine speeds the intake charge has enough of an opportunity to dwell in the inlet tract that the coolant temperature can effect the temperature of the charge, this is more noticeable on engines that have long inlet runners, or deeply recessed inlet ports. At higher engine speeds this effect reduces as the mass flow is higher and the charge has less time to dwell and transfer heat from the walls of the inlet.

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