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Map Resolution

Practical Dyno Tuning

Discussion and questions related to the course Practical Dyno Tuning


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Currently tuning my MK3 Supra at 'confirming on the road' stage.

within light load areas, 50-30 KPa i have come across a tricky spot, which is either rich before ecu decides to activate decel fuel cut.

however if i adjust fuelling to correct this, under acceleration (2 - 5%) throttle the engine will go lean.

if i were to increase the resolution of the VE Table at this point (say add in areas 20 , 30, 40, 50 Kpa) would this help to fine tune this area? as there will be less of a jump between VE values when the ecu is interpolating between cells.

Thanks

Sam

Post screenshot of the table.

Main areas within the map are 1600 - 4300 RPM cruising between 30 - 50 KPa on and off throttle

Attached Files

It can be useful to add a little additional resolution around the light load areas to help dial in the fuelling more accurately. You are also best to disable the fuel cut while you're trying to tune the light load areas. My guess is that the problem you're encountering is to do with interpolation to surrounding cells. The only other point I'll add is that you may see the AFR move rich during a sharp lift of the throttle. This is essentially the opposite of what happens when we accelerate sharply - Under accel the AFR moves lean and when we get out of the throttle the AFR will move rich. Some ECUs allow this to be dialled out but it's important to know that it may be affecting your tune.

Andre,

To your last point about the major swings in AFR when applying or removing the throttle, what allowance should you have with these transient in AFR?

I would think large changes in amplitude with longer periods would result in misfires. So using the M1 I would expect this to be all in fuel film tuning with the quick adjustment.

Any thoughts?

Is there a reason why the rpm and MAP breakpoints are in such uneven increments? 4293 rpm to 4820 and then 5266? I understand wanting more resolution in particular areas, but you will find that interpolation is easier when it is even increments that are closely related. So for example, 20 kPa and 10kPa increments, 500 or 250 rpm increments. Jumping around like that makes it difficult to adjust the tables and get the desired result.