Need advice dialing in cold start

[Townzenator]

I've had my 89 supercharged MR2 with the 4AGZE running on the DIYPNP (MS2 Microsquirt based) for just over a year now. It runs great most of the time, I just can't seem to get the cold starts perfect, especially since the weather has gotten very cold lately in CA. I'll be attaching my current tune and log from this morning, some of the issues lately are that the car will start but die immediately when cold on the initial start. The second start it will stay running but will run rough, either very rich or lean, for a few seconds. I'm not sure if it's misfiring from overly rich and showing lean from extra unburnt O2 on the WB or if it is lean. I'm guessing it really is lean since I've lowered the ASE quite low and my WUE isn't very high.

I also noticed the idle valve is staying open at the 70% cranking duty for quite a while, should I have it close a lot quicker and maybe that will help richen the mixture? I had increased the close time because I had another issue where the car would start, idle for a second, RPM would raise, then suddenly drop very low or stall. The other issue which you can see on the log is soon after a cold start if I give it throttle and let the clutch out to accelerate it goes very lean. Should I just add some more cold accel adder/multiplier in the accel enrichment? Let me know if anyone sees anything obvious I might be missing here.

Thanks,
Mike

I forgot to mention, the VE table might look a little odd above ~5psi because I have water/alcohol injection that activates at that point, also why timing is pretty aggressive above there too.

[72bluetr6]

I'm not a pro, but I have tuned my cold start satisfactorily- here in Sacramento. OK, you guys from Canada, I mean low 40's F..... not cold cold. But the cranking chart is a % of required fuel and the ASE is % added above required fuel in MS3. So I'd say you typically don't want below 100% values in the cranking table and you'd want more than zero enrichments ASE. I'm sure some pros will jump in to assist.

[Townzenator]

Oh, okay. I'll increase the cranking % some more, I did increase some this morning but it still died on the first start then stayed running on the second. I increased the WUE by 1% in the lower temps since while warming up it does seem to start hunting a bit. I did increase the ASE at low temps and it behaved much better when it started this morning, it was very cold today as well (right up the hill from you in Diamond Springs next to Placerville). Thanks.

-Mike

[72bluetr6]

Engines differ quite a bit, but for a starting point at 40F, try 300% cranking pulse, 70% ASE -and so you can evaluate what is going on, extend the taper to 700 cycles- and just linear down to 101% cranking pulse, 1% ASE and 200 cycles at 150F for each of the curves. Hopefully, this will get you up and running in the ballpark so you can adjust to suit.

[Townzenator]

Changed to values close to what you specified (except ASE starts at 31 @ 20 degrees F) and this morning it started great on the first attempt at about 30 degrees outside and warmed up fine. I also added a bit more WUE, thanks a lot.

-Mike

[72bluetr6]

Great, thanks.