MicroSquirt.com read only forum (Jan.15,2018)

Jedrik -I was talking about constant TP in the first place - foot to the floor in gear from a rolling start. Once the turbo hits 15psi (easily by 3500rpm) the AFRs are still running lean.
My AFRs go from 14:1 to 12:1 over the space of a second or so in1st and maybe 2-3 seconds in 3rd or 4th despite all the cells used being tuned to 11:1 or 11.5:1. Thats a long time to be lean on a 300 crank-hp 2litre turbo.

The only way i can see around it is to run rich in the cells above and before the main diagonal to ensure im running rich enough on a worst case, but that means losing torque due to overfuelling at lower revs. Cant win.

J

I think I am fighting the same issues.

I have a 400hp 2.3 turbo with 25 psi boost. MSII V2.35.

The problem for me is this. I am at cruise and would like VE table to reflect my desired 16 to 1 AFR that is no problem I can pull out the fuel and it cruises fine in 5th gear.

Now cross that same load and RPM point in in 2nd gear at a gentle accel (no gas pedal motion, no accel enrichment can be added) and it is sooo lean it missfires and stumbles and kicks and goes way off the end of lean end of my AFR meter.

The only way I have been able to get a semi working tune is to set the VE table for the 2nd gear mild accel so it at least shows 15-16 to 1 (this is not into boost). This still has a little hesitation under some situations.
The same load point under cruise in 5th gear is now a nasty 12 to 1 AFR. I have my EGO correction setup fairly well so it can fight its way up to the 15.5-16 to 1 set in my desired AFR table.

But this is a patch at best, an accel event, even a dip in the road bumping the accel pedal knocks my EGO correction back to 100% and it has to fight its way back. I tried making my accel function less sensitive to avoid knocking the EGO out but then I make other problems. If I make the EGO more aggressive it starts making a real mess.

Maybe it is worse with a turbo, but I have a friend and he is noticing the same thing, a real gentle accel can bring you across a load and RPM point in 2nd gear that you cruise at in the 5th. The VE required is much different.

I did not have this problem with my V8 automatic. It seems the loose stall makes it more of a constant load situation.

I to am looking for ideas on this. I would really like to lean out my VE table so it cruising at the AFR I desire and not working on EGO correction alone.

It maybe that the turbo is making this worse because it does add air without a swing of the gas pedal, but if I add more MAP based enrichment then I have issues at full boost, the slight boost fluctuations are kicking the MAPaccel in and messing that up.

Seems like a common issue, ive had a few people say this now. And it does seem linked to turbocharged, lower displacement engines. We could do with an RPM tracking enrich function - AE that reacts to the rate of rise of RPM and is independant of normal map/tps AE.