eco tuning - low rpm rich vs throttled high rpm lean

[ever_green]

I'm currently tuning cars for best driveability and mileage in drive mode and I need to figure out

Is it better to

A) accelerate at near full manifold pressure (99% load) at low engine RPMs (2000 rpm Shifts) and run rich (13.5:1 AFR)

Or

B) accelerate at moderate MAP (70% load) induced by low throttle opening but higher RPMs (3000 rpm shifts), yet running lean (14.5:1 AFR)

This tune is done by modifying drive by wire tables. AFR needs to be enriched to cool down engine when under full load.

[ever_green]

Originally Posted by Old Tele man

IF the engine electronics includes a *knock* sensor, keep it lean until the sensor *tells* you (via the ECU) it's time to go rich.

unfortunately that's not possible. however the knock sensors do control the timing. I can run retarded timing and do lean accelerations. however the exhaust gas temperatures become unhealthy and power suffers.

[jani]

Any member with 250+ posts can submit their own or any other member's project threads to the library by clicking the "Add this thread to EcoModder's Project Library" link that appears at the top of the first post, eg:

[serialk11r]

At 2000rpm I don't think running rich will be a productive use of fuel. Remember, running rich is to improve combustion speed, and at low rpm you don't need to worry about combustion speed as the engine is turning over slowly. At high rpm, going rich will help the engine develop a bit more power and the excess fuel will be doing some useful work.