Running lean on acceleration
Turbo Mini Forums

Hi guys,

I'm trying to get my head around EFI tuning. My car is running rich on acceleration and (anything between 10.8 and 11.5) and on cruise (around 11.8-12.3), i did a bit of live mapping today and took some fuel out of the table in the cells where it was on cruise, and a tiny bit out of acceleration. Now the car is around 14.2-14.8 on cruise and in the low 13's for acceleration however i've discoverd something since doing it - as i put my foot slowly down on the accelerator, it initially dips into the 15's and 16's for a second then goes rich again. Is there usually a table to cater for the inital acceleration? As the acceleration table changes don't appear to alter it.

SXTune, D400 ECU.

I'm not familiar with the SC setup and software but on most ECUs you should have a choice of TPS or MAP based AE and a choice of how much of each to use.

On the MS2 with the firmware I use, you get two separate tables for the AE adder, one for TPSdot (rate of change of TPS) and one for MAPdot (rate of change of MAP) and you select how much percentage of the overall control you want each of the tables to have.

But if you are experiencing the issue with very slow throttle opening it doesn't really sound like an AE issue (because TPSdot and MAPdot will be so low that little or no AE will be added), more like a basic fuel value in those cells issue, and being hidden by excess AE when you open the throttle fast.

Schrödinger's cat - so which one am I ???

My gauge shows lean momentarily when i change gear or plant the throttle. SC setup. It isnt hesitating. Im wondering if the wideband has a little bit of latency before it catches up?

Chris at EFI Parts sorted it for me in the end :) nice healthy (non detting) 150lbft @ 4500rpm

AE - Acceleration enrichment table.

Thanks Steve.

I will persist with the AE table but as you had originally stated changing this doesn't seem to change things a great deal.

Do you know how much he changed things (assuming you still have the setup in your car)?

Sadly not. My D400 went in the bin last month.

No problem. I have half a mind to do the same.