Hi all, my name is Jason and I’m new to the WRX scene and looking for a few pointers. I am not new to cars having previously owned classic American muscle cars over the years but definitely new to modifying cars with ECU’s. I considered all options Regarding the engine but as it has done under 200 000ks and still very strong I have opted to go for very minor mods and I will look to keep the engine close to stock for reliability purposes. What I am interested to know though is at what point do these mods impact the tuning side. I am looking to do the following,



1. TBE
2. TMIC upgrade
3. Fuel pump upgrade
4. BOV upgrade

Would these changes combined cause a tuning issue or the need for new tuning equipment? I plan on changing out old sensors at the same time and maybe fitting front and rear sway bars. Still getting my head around some of the language relating to modding “modern” cars. Thanks for reading and look forward to any feedback you can pass on.

Cheers

Welcome, Jason!

The 1993 to 2000 WRX and STI's are quite forgiving when it comes to modifications and the factory ECU tune - you can run a TBE, upgraded TMIC, and an upgraded fuel pump with the standard ECU tune without causing problems. The car would make more power and the power delivery would be smoother if it was retuned, though.

As far as the blow off valve goes - you can run a fully recirculating valve without running into tuning issues.

There will be issues with the way the car runs with an atmospheric or semi-atmospheric blow off valve. The ECU can't compensate for air leaving the intake system any other way other than through the engine, but once you run an atmospheric BOV, you're introducing another exit point. Usually results in poor idle and the car running excessively rich.