ECU Swapping

[monty2982]

So I see people selling ECU's with stage XXX software already installed. Do you just pull yours out, install the loaded ecu and voila you have stage xxx installed? I called a local dealer and they said its not even possible to do so. They said you need to have a authorized dealer install the software and that only the B5 S4 platform is capable of ECU swapping. If I can buy a ECU with the software installed already for cheaper but cant even use it then how are people selling them and the buyers able to use them? I have an ECU with APR stage 2 lined up to purchase used for my 05 1.8t a4 from a member, can this just be plugged in and used or is the APR dealer just teling me it cannot so that I buy new from them?

[CyberPMG]

There's a few things to watch out when dealing with swapping out ECUs. First, the ECU needs to match the year of your car. You would need the ECU to come from a 2005 A4 1.8T (preferably the same transmission too). Even if you have the same year, the ECU won't drop in due to the immobilizer coding in the ECU. The immobilizer is unique to each car for security reasons. Your keys are coded to match the immobilizer code that exists in the ECU. Without that match, the car won't run. The immobilizer cannot be recoded through any VAG-COM tool. A special tool is needed that is only available at the dealer (which then goes back to a database at the factory). To make matters worse, APR's software is also registered based off the immobilizer code. There are programs that can defeat or bypass the immobilizer, but then you will loose that safety feature.

Your best solution is to go to the APR dealer and let them flash load the Stage 2 software directly onto your existing ECU through the OBD2 port. It's very easy and simple to do without the need to physically touch the ECU.

[monty2982]

Yeah APR was/is the plan. However, if I could have purchased a preloaded ECU with the exact same settings that I will be purchasing for $500 new and save $150-200 by purchasing used and being able to plug right in then that would of been my option. With the time and money invested into the the immobilizer...you get the point...budget builds.

[CANTA4DIT]

Would be nice if there were less variables but by the time you found an ecu with the same year/engine code and invested in vag-tacho got the skc to program the immo for your key, and used vcds to re-code the ecu to the right transmission/drive train setup, you could have invested in APR software and have the support to go along with it. Just my $.02