Hi guys,

I have a 2009 Evo X MR that has been manually swapped. After driving it for a while, I started noticing understeer, especially in wet and snowy conditions.

After doing some research, I found that I may need to replace or reprogram the ACD/AYC controller so that the transfer case and AYC pump behave like the GSR model. The goal is to prevent the transfer case from locking too early, which should help reduce understeer.

My questions are:

1. Where is the ACD/AYC controller located?
   Is it in the passenger side of the trunk, or under the driver-side dashboard?
   
2. Option 1:
   Can someone guide me on how to program the ACD/AYC controller, including which firmware/file is required?
   
3. Option 2:
   If I decide to purchase a GSR ACD/AYC controller, could you please:
   • Confirm the correct part number
     
   • Explain how to distinguish an MR controller from a GSR one
     

Any guidance would be greatly appreciated. Thanks in advance.

 

The AYC/ACD is the same as far as I know, along with the programming and controller (there is only one part number). The ACD controller I believe is in the passenger footwell, I've only heard of one company reprogramming the stock unit, but you will have to search, can't remember their name. The t-cases and rear diffs are also the same.

If you are having AYC/ACD issues, it's likely with the pump (which is also the same across models), maybe air in the lines.

 

Read through this thread: https://www.evolutionm.net/forums/ev...-complete.html

This is the dude from Kozmic Motorsports one of the leading MR SST shops in the US. If they don't mention anything about AYC/ACD, you are chasing the wrong problem.