I am currently having a problem with my boost of my FD series. it was working fine until I took it to a mechanic that said he knew what he was doing. I upgraded my intake, piping and IC (so theres no leaks there), took off my cats with 3" straight pipe back, added a boost controller and fuel programmer. it started backfiring due to low backpressure and when we went to dyno tune it the boost dropped to around 5psi. I got a wastegate actuator and map sensor, put them in and still nothing. he managed to take out the backfiring but still no boost. I left disapointed looking for a new tuner. later, my battery died and I had to jump start it; when it then started backfiring again. I read forums without much help and im thinking it may be an electical problem rather than a common vaccum one, thoughts....

 

It sounds like your tuner changed a whole bunch of stuff at once and didn't know what he was really doing.

First, going straight-thru 3" on an FD is a bad idea unless you've removed the turbos to port the wastegate. Catless exhaust with intercooler and intake is usually enough flow to cause the airflow to choke at the wastegate, especially in cool weather. No ECU or boost controller can solve that problem.

The low boost might be your saving grace because all of those flow mods would have risked blowing the engine on overboost.

When you say it's backfiring, you mean big bangs, right?

The electrical problem sounds like a seperate issue.

I'd take it to a rotary mechanic.

Dave

 

I have gone through similar problems a while back. Tried just about everything. Ended up being the wiring harness. If yours has never been replaced try checking it around any areas close to any of the exhaust, turbo, manifold ect ect... Just something you can do yourself.

 

Well it ended up that my boost controller shorted out bc of bad wiring (connecting multiple wires to the same ground). Sorry for such a long delay, been busy getting everything fixed. I eventually got a Power FC and also got a new wire harness because mine looked on its way out and why risk it. Anyways thanks for all the help though....its running great now