GenBoard/UnderDevelopment/AccelerationEnrichment

Acceleration Enrichment (Transient Fuel)

Our current accel enrichment is showing poor drivabiliy issues because the engine's acceleration requirements change with engine speed.

This is especially noticable on smaller (<2000cc) engines where users have complained about the fact they can get the enrichment correct at lower speeds, but then get issues with the engine bogging through being too rich at higher RPM.

Suggested Solution

Accel Enrichment Duration is calculated based on RPM, and scaled by dV/dT.

Accel Duration

Accel_RPM[0...3] defines the RPM break-points

Accel_Duration[0...3] defines the duration in mS corresponding to Accel_RPM.

TPS Scaling

DV/DT[0...3] defines throttle change speed break-points (in the same method that we currently use).

Scaling[0...3] biased at 100% so that enrichment values can be tuned with a fast TPS change speed, then scaled down for slower speeds. Or with slow speeds and scale them up to suit faster TPS change speeds.

Solution

Thanks to Sambas this is now in the 1.0.79 firmware (still in Alpha at the time of writing)

http://kotisivu.dnainternet.net/sakrkorh/vems/firmware_1.0.79alpha.zip


[dnb] removed redundant comments

I have issues with this on a 5000cc engine, although they aren't anything like as severe as other people's problems here. MembersPage/DavidBlades

Im seeing the same issues, even with a 2500cc engine, MembersPage/GunnarReynisson

I had horrendous trouble with this on the Mini 1400SPi MembersPage/Sprocket

I also have the same problems, on serveral car, Impreza/Legacy 2.0ltr,2.5ltr, and Vw VR6 Turbo 2.8ltr MembersPage/Skassa

Calibrating Accel enrich is a question i getfrom tuners using the software. MembersPage/Irishtwincam

I believe this to be something that should get priority to implement. MembersPage/JasonRussell

I'm also building a Mini injection setup and will come acorss the same problmes as listed by Sprocket. MembersPage/GavinWilkinson

I vote for simple in tuning algorithm. suggestion is simle. But it must be possible to tune for good results for all driving conditions. Current version is too simple for it. And I miss deceleration enleanment too! I see OE systems where AE is based on alpha-N table. With current analysis software it takes half of hour to make additional reasonable 8x8 alpha-n table. May be this is the way? Also: can someone explain what we see in 1.1.41 in experimental area regarding AE? MembersPage/GintsK

Experimental AE/DE/Film is a simple film model implemented from example Lada OE J7ECU for my tests (of course it is excluded from FW by default).It is not MAP or TPS based, but air_quantity based. It calcs pw_air_q_based = (req_fuel*MAP*VE*Gair). Film: PWfilm = F(air_q, CLT), compare PWfilm and PWfilm_last, and + or - difference to final PW. ACC/DECC: if (tps-tps_last>deadband) PWadd/sub=coeff*(air_q-air_q_last). For decay use simple acc_corr = coeff * acc_corr_in_last_cycle, it is non linear. Separate decay coeff used if acc/decc starts or continues in current cycle. All calcs is cycle based but not time based, and separate for each cyl. Not even one test performed, only bench and PC tests, i'll try some tests near months. - MembersPage/Andrey


For clarity the previous information has been moved to

GenBoard/UnderDevelopment/AccelerationEnrichmentOld