Many Q's, injector sizing, chip burner, boost fuel

[nickmpower]

I've been looking at the files for my 1991 318is 175 ECU. I am installing a Downing atlanta supercharger and plan on doing my own tuning. I have a wideband and my friend is letting me barrow his data logger.

The first question is injector sizing. I have seen the map scale factors but have no idea how I would adjust these for bigger injectors. I'm thinking that most likely I will multiply by the stock injector size and divide by my new injector size?

For creating the base map, I want to adjust for boost. Knowing the boost level at certain RPMs, I was thinking I should multiply the fuel values by atmospheric pressure plus boost and divide by atmostpheric pressure. This seems like it should be pretty accurate for accounting for the extra fuel.

Also, what devices are you guys using to burn your chips? obviouly I am going to most likely be making many versions of this tune before i get it perfect.

this unit looks pretty good
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0124490071

[ecuconnection]

I suggest using ostrich2 with tuner pro. tracing is lots of fun

[revlimit]

to tune for bigger injectors, you only need to tune AFM constant map, lower all 8 values down to reac proper air fuel ratio.

[revlimit]

I suggest using ostrich2 with tuner pro. tracing is lots of fun

Here is the video on how the trace looks:

http://www.youtube.com/watch?v=8F2VjIFNID0

[nickmpower]

ok, how would I go about adding rows to the WOT fuel and ignition maps? I am raising my rev limit to 7200 and the stock map stops at like 6320. I would like to add some more rows for my higher rpms. and maybe add in more values in the current RPM range for better definition

by right clicking and going to edit XDF info then to rows I can change the number of rows but i am unsure if this will be seen by the ecu?


also there are so many different low throttle and high throttle maps, when are they used? I realize the tracing will tell me this but i would like to create a good base map.

my car is a 1991 m42 318

here is the XDF
http://tunerpro.net/download/bindefs/BM ... oft378.xdf

here is the bin
http://tunerpro.net/download/bins/BMW/3 ... 356378.bin

[revlimit]

I made that XDF for 175 ecu, I included all known maps, because I don't know which maps ECU actualy uses, I would need comercialy tuned bin to see what is changed then I can make the XDF more simple. Maps can be expanded and RPM and Load values can be expanded too, but this is not included in the tunerpro for motronic, because motronic is wierd, it calculated backwards.

I expanded the maps in the 173 hakentt file, you can see it and you can see how I did. You got to be advanced hex code editor to be able to do this.

[Justin517]

what if you dont want to "expand" the maps by adding rows or colums, but you want to change the values of the scales, keeping the same number of points?

if there are 14 points for RPM and they go up to 5600 (with 400 rpm between points) could you simply extend it to say 7000 rpm with 500 rpm between points?

or does that require being an advanced hex code editor too?

[hussain]

Ostrich is lots of fun just try it logs nicely

[DmcL]

to tune for bigger injectors, you only need to tune AFM constant map, lower all 8 values down to reac proper air fuel ratio.

doesnt quite do the job.. it will lean out fuelling but it makes the overall airflow curve become choppy. try lowering just the 8 values u mentioned in that spreadsheet of the AFM maps and see for urself.

the way i tune for injectors now is to just re-scale the fuel maps to suit the injectors. i ran 30lb injectors this way with no problems at all (stock injectors are like 14.7lb so a little over double the size).

an easy way to roughly scale the fuel maps for any size of injector is to do it this way:

stock injector size (14.7lb for example)
new injector size (30lb for example)

14.7 / 30 = 0.49

now select all cells in fuel map and multiply by 0.49, repeat for each fuel map as necessary and then verify/check AFR with wideband and fine tune as necessary.

u can also do it another way:

30 / 14.7 = 2.04

select all cells in fuel map and divide by 2.04, repeat for other fuel maps and verify with wideband/fine tune as above.

in my own experience tuning for injectors this way the calculated value is damn near right on the money every time and only requires minimal fine tuning after re-scaling the fuel map.

the only think to watch out for is if ur using significantly larger injectors such as when i was running the 30lb injectors in my M20.. u will also need to scale the cranking fuel maps otherwise u will have starting problems as the engine will be getting drowned with fuel when cranking.

@ justin, u can resize, rescale, change a single point or all of them, etc, etc. but u would really need to be able to edit the values in the raw code to do this kind of stuff unless u ask someone nicely to make a file with whatever RPM points u want and also modify an XDF to correspond with the modified RPM points in whatever maps have been modified.