COS3 or COS5?

[00RAPTOR]

Hey guys...newbie here...with a "newbie question. I have a 2000 t/a a4 and i'm changing the OS to an '02 stock version i got from holdencrazy.com., and after i got that done, i realized that guys are then changing to COS 3 or COS 5....what does that mean? can i do it? and is there a sticky or anything on how to go about doing this? appreciate the help guys!!!

Justin

[00RAPTOR]

I think i found my answer....is this what they mean? first i need to do a full reflash of the cos that corresponds to my op system for the '02, since i am upgrading to the '02. then i need to do a calibration only reflash of my '02 tune?

[ringram]

Yes Sir basically. Go with COS5 its the same as COS3 but with more extra features to play with. In fact no point using anything other than 5 if its available as the higer numbers are generally supersets of the earlier custom os's

[00RAPTOR]

i can only find up to cos3....atleast in the tutorial....is it somewhere else of have i been staring at efi for too long? also, thanks ringram...it's starting to make some sense

[dfe1]

The only potential "problem" with COS 5 is limited availability. I haven't checked the latest cals, but at one time it was only available for OS12212156. That's not an issue with the 1999-2002 PCMs which contain .5 meg operating systems, but the 2003 and later PCMs have 1 meg operating systems. These comments may now be irrelevant, but I figure they're worth noting because not everyone is using the latest software.

[joecar]

00Raptor,

Welcome to the forum...

If you have a 2000 PCM, then do this:

0. read your PCM and save to file; copy to multiple offline locations (e.g. to CD and to USB memory FOB; store in safe places) for backup;

1. copy all your tables to OS 12212156: open 2 tunetool instances [one on your existing tune file, the other on a 12212156 file having the same transmission as your car], copy each table ane-at-a-time (takes about 1 to 2 hours of concentration), save the 12212156 file with a new filename; be very thorough and accurate in copying the tables (it will save you time later);

2. do a full flash write of the new file into your PCM;

3. make sure your car runs; if not, go back to step 1. and check all your tables;

4. follow the COS3 tutorial (comes with EFILive software) to flash COS3 or COS5 (see next step for obtaining COS5);

5. if flashing COS5, see post #228 in this thread (and follow the extra notes): showthread.php?t=2599&page=23

Various people have successfully done this jump to COS5 from their 1999-2002 Y/F-body PCM's.

Cheers
Joe

[00RAPTOR]

Appreciate it guys. Real quick, is upgrading to a cos make it easier in the long run to tune ur car?

[Beer99C5]

Appreciate it guys. Real quick, is upgrading to a cos make it easier in the long run to tune ur car?

COS 5 adds features for Forced Induction and Nitrous Applications. If your not using either, no need to use COS 5.

I have a thread that goes details any problems I had and their fixes. The forum was a great help (PM's and phone calls).

[5.7ute]

Cos5 also has the alpha n fuelling option(TPS/RPM) which helps in taming big cams.

[joecar]

COS3/COS5 also change the OLFA table from ECT vs MAP to RPM vs MAP allowing better control of commanded AFR.