Looking for info to complete my diy safc.

[nikwal]

So it's winter here and sometimes too freezing cold to be in the garage(or I'm a bit weak heh) so I decided to do a little coding with a circuit named AtMega8, first I just measured rpm and the karman-vortex frequency from the lmm. Then it kind of evolved into a afc. Anyway, it's winter here and I've got no snowtyres and hell, the turbo is'nt even fitted on the car at the moment so taking the monster for a drive to find out the maximum frequency the air mass meter is putting out is'nt really an option now. I saw a number on a random page online from another car that said 500cfm for 2khz but I've not seen any numbers on 7mgte or lexus. If someone have any info that would be great.
Also, I'm not sure what functions to implement. So far i've got two maps, one for high tps and one for low with 9 different rpm points(non user configurable,but easy to change in the program). low/high Tps points are configurable in %. Tps also has learn mode for setup so you calibrate first where 100 and 0% are almost like in megasquirt exept everything is done on a lcd display and four buttons. rpm and tps are interpolating (of course).
I have made the maps so there is a "base value" that goes +-25% in 0.5% steps. This value is always ON.
The separate values at each rpm can be changed +-25% also for a total of +-50%.
low cutoff frequency is now 17Hz and high is set to about 3khz.
The program has functions for total reset and save for one car and settings for nr's of cylinders.
I know this text is a bit messy, but any input in how the program shoud work is appreciated.
This project is intended as a relativley easy and cheap diy project with one reservation, that I won't give out the source code to just anyone(sorry). At least not until I see that it's working a 100%..

 

[nikwal]

http://dsl.mine.nu/nafc.htm Contains pretty much all info needed to build it, if you think a bit for yourself and look in the datasheets.. I'm in the process of making a circuitboard layout in eagle..

Just realized I made a video a while ago..
http://www.youtube.com/watch?v=aA23vuj1s2k
(sorry about the cursing, I did'nt really think I would use this video)


Unless I missed something really major, this changing pulse length or frequency is'nt really hard to program. When I get some time over, i'll look into changing the injector length instead, the program will never do both though, there is only like 22% left of flash to put some goodies in..




[EDIT]
I've been updating the program A LOT. http://dsl.mine.nu/nafc.zip now acutally contains a lot of stuff, schematic and board layout, history, manual...
15% program memory left for goodies

 

[nikwal]

Finished... does it look aaight?

installed it in the car today, sort of permanently, still a thick layer of snow outside though and got no winter tyres... buääh

2% memory left for goodies ;-)
...

[Edit] Making experimental MAP*RPM = flow conversion from mapsensor to lmm ecu frequency, If flow = map*rpm * scaling + offset is true, it should be fine...karman is linear, is there any reason that should'nt work?.. anyway, two hex files ,one with adjustments for idle frequency (offset) and wot frequency(gain)... using mpx2450ap sensor.. the routine simply shuts down the interrupt int0 that reads karman freqency and a copy of the int0 service routine is placed in the main loop instead.. (yeaaah i've got too much spare time,)
(I'm doing this project to learn more, not to get rich)
0.9% mem left for things.. damn soon i'll need a mega16,
[edit] I'm not abandoning this project, just putting it on ice until it an be tested more thorougly.. Trying to learn more about ansi C in Codevision in the meantime, The last program was made in some weird kind of basic(works actuall pretty good) and is almost at 450lines of code now..