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View Full Version : How To: Recode CH ECU to work with M 2001 B5 A4



nostradahmus
05-09-2012, 08:10 PM
Just putting this information all in one place, as I had difficulty finding it:

Steps to get a CH chipped ECU to work with an early 2001 A4 M Ecu Car

1. Find yourself a chipped ECU, mine happened to be a GIAC
2. You will need a VAG COM, but the full version is not necessary. Assuming you don't know some one who has one, vist eBay and choose one of the many offered there. Should be a blue cable with mini CD for around 20 bucks
3. Download ROSS Techs VCDS lite software here http://www.ross-tech.com/vcds-lite/download/index.html and install
4. DONT START CAR...Turn your ignition key to on position WITH YOUR STOCK ECU plugged in and hook up your pretty blue cable to USB and the OBD port under your dash
5. First test your connection as instructed, mine ended up being COM3 your results may vary
6. Once your connection is established, click Select Control Module, then Engine
7. It should pull up your ECU part number, mine ended in 018 M....under that should be a software code...this is the number that needs to be changed on your new chipped ECU replacement
8. Record the number and follow this process http://www.a4mods.com/index.php?page=webcontent/pages/ecu.html to remove your stock ECU
9. Install your chipped ECU and briefly run the car (for like five seconds, any longer it will stall) Redo step six for the new ecu, this time click Recode Module.
10. Record the original software code for the chipped ECU (in case there is a mistake) then remove and replace it with the code from your stock ECU
11. Take it for a test drive, before your put it back together, bring your stock ECU just in case
12. ENJOY MORE BOOST

EDIT: On the way to work today the engine stalled out, just as it did when I originally tried to run the CH box without recoding it. Had to pull it out on the side of the road and swap back in my stock M ecu, which I was smart enough to leave in the car. Have not had a chance to investigate it further. I have read some people report needing to change the code a second time as it does not save initially. Hoping this is the issue. Updates to come

UPDATE 5/14: I called GIAC today, told me the stalling issue was a common problem with the chips that are removable. For $100 you can ship your ecu to them and have it changed to the newer flash technology. I did so immeidately.

http://i1225.photobucket.com/albums/ee389/nostradahmus/RecodeInstructions.jpg

walky_talky20
05-09-2012, 08:36 PM
Nice writeup.

Did you find that the CH ECU causes a couple constant fault codes regarding the brake booster pressure sensor and/or brake vacuum pump?

Mine had those codes because obviously that equipment isn't present on an early/M-equipped 2001 car. I should clarify that those codes did not cause a CEL, they were just stored codes. Also, it only happened with the Tiptronic trans (and appropriate Tiptronic Trans coding). After my 5-speed swap (and recode to 5-speed), I no longer get those codes because the brake vacuum equipment was Tiptronic only.

nostradahmus
05-10-2012, 07:44 AM
Edited my original post. Everything ran great last night, but on startup and drive to work it stalled out like two minutes into my commute...hoping to get it fixed tonight

walky_talky20
05-10-2012, 08:33 AM
I'm not sure the coding is related to the stalling. That may be an issue with your specific ECU (ie: a faulty ECU). After it stalled, would it not start back up?

Generally speaking the car should run fine even with incorrect coding. It appears the only coding value you are changing is from 5-speed to Automatic. People have swapped their cars to 5-speed and driven them with Tiptronic coding without issue. I did it myself. I've not done it the other way, but I can't imagine that it would create random stalling problems. Perhaps a wonky idle or something.

biketsai
05-10-2012, 08:53 AM
I'm not sure the coding is related to the stalling. That may be an issue with your specific ECU (ie: a faulty ECU). After it stalled, would it not start back up?

Generally speaking the car should run fine even with incorrect coding. It appears the only coding value you are changing is from 5-speed to Automatic. People have swapped their cars to 5-speed and driven them with Tiptronic coding without issue. I did it myself. I've not done it the other way, but I can't imagine that it would create random stalling problems. Perhaps a wonky idle or something.

I've driven my car with my ECU (back when I was tip) configured to 5 spd. It seemed to stay in like 3rd gear the entire time while driving and it was pretty difficult.

walky_talky20
05-10-2012, 09:27 AM
^Yeah, the TCU would probably freak out and go to limp mode. But the engine should still run fine.

freekonwheelz1
03-14-2016, 12:47 PM
does this work in reverse? i have an M ecu that somehow changed itself after i flashed eurodyne nto it into a CH ecu. i need it to think its an M ecu again so i can use my eurodyne software on it again...