COS3 or COS5?

[00RAPTOR]

:help2: 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... :cheers:

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 (http://forum.efilive.com/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
:cheers:

[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.

[00RAPTOR]

thanks for all the replies guys... i have the '00 to '02 upgrade done....now i just have to wait for my car to get back from the paintshop...i just bought a raptor hood for it :rockon: but i can't wait to see if i did this tune right....thanks again

Justin

[TAQuickness]

Welcome to the forum 00RAPTOR. COS5 is the way to go if you're needing a custom OS. My current setup is a heads cam 383 and COS5 was the solution to daily drivability. The beauty of COS5 is that when the new build (boooooooooooooooost) finds its way into the bird, COS5 is already in place and ready to be tuned.