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

Hi,

All the time I've been tuning so far, I tend to get extremely high VE values in the low RPM/medium to high kPa when using MSTweak. I've once seen a topic about it where people talked about air leaks in the buterfly axle that would allow for a sudden increase in pressure as soon as the throttle was depressed. The proposed solution was to use high VE bins in that zone to cure it. I did it without much success and I still stumbling when the engine idles and I give a kick on the throttle. AE does not much to change the situation.
Also, when the the engine is in the 1500 and 2200 Rpm bins under full throttle (about 90 kpa), it stumbles until it gets into the 3000 rpm/90kPa bin. Then it starts pushing like hell. I've tried enriching and enleaning the incriminated zone and nothing does the trick.

Are these issues known ones, are they separate or not??

Attached is my latest VE map and 2 HDMAP files (from two separate bunch of logs) zipped for you to see and hopefully comment.

Thanks in advance, Séb

Doesn´t the VEbins at 80/90/100 kpa look a bit low in those areas compared to the rest ?

I´ve just got my own car and how i´ve adjusted that one as reference though....

I run Autotune now instead of mst3k and it´s doned wonders for the drivability compared to mst3k. Altough the first reason was that i wasn´t able to get the logs into mst3k

I´m not very experienced when it comes to mapping though ,have a lot of experience in tuning carbs so i try to incoroprate that into it.

You need a Wide Band O2 to really tell what's going on .

Also , what is your ignition advance under the stumbling conditions ?

Extremely retarded ignition timing can produce the same symptoms
or could be aggravating the situation .

Keep advancing the timing until you get the engine to "Knock"
(detonate) between idle and 2000 RPM and then back it off
about 5 degrees , you may find that your timing is not
what you think it is .

Also , check to make sure that you don't have any vacuum hoses
off or leaking , I spent about 15 hours tuning with a vacuum connection
loose and actually got the engine running pretty good .
Then I had to start all over again when I found the open vacuum tee
that was in the same hose going to my MAP Sensor .