I just installed a 3" TBE. I was planning on doing the mechanical o2 sensor fix tomorrow, but took the car out for a drive tonghit. Also, instead of putting the o2 sensor back in I just left it out and used the screw that came with the exhaust to cover the bung. So anyway, I am driving the car and it feels good and then I get to 4th gear and just hit the gas at around 65mph. It pulls ok and then bogs really bad, I think there was a fuel cut or something, and then my service engine soon light came on. I am going to put the o2 in tomorrow, but is this really the problem? Also, how do you check the code when the SES comes on?

 

Take you car to Autozone and they'll check the code for free. Maybe you overboosted?

 

I didn't notice if I overboosted, but I don't even have a boost controller so how could I have done that? If I did, what code will that throw and what damage have I done?

 

usually changing to a turbo back with no cat causes the peak boost to rise 2-3 psi over stock and you could hit fuel cut, you need some form of boost control.

 

You are a disaster waiting to happen. With an exhaust, the boost shoots higher, because there is less backpressure. what made you decide to leave the o2 sensor hanging instead of plugging it in? Also, an MBC should have been put on a long time ago. Why do you have an Ebay intake and $200+ BOV, but no MBC or tune? That's ***-backwards, and now this exhaust craziness is just another blunder. Striaghten up, KY!

 

I just found another post with someone with the same mods and problems. He also was driving on a cold night which he said made his boost hit higher than normal. I am gonna get the code check and also finish mechanical o2 fix and buy boost controller.

But the bog I felt was just a fuel cut from too much boost? At what PSI does the fuel cut?

 

Your hitting fuel cut/boost cut. Basically by having a new free flowing exhaust with no boost control or tuning your most likely getting boost spikes from the increased flow. This happen's on just about all of the Evo's. Once you get a boost controller and tuning this will be fixed. I wouldnt worry about damage this loss in power that your getting is the Ecu's way of protecting your engine.I would say you CEL is most likely a Cat insuffeciency code #2 you cant leave the rear O2 sensor out of the flow. It doesnt effect performance but does work in conjunction with your emission system. All it needs to work is to have a different signal than the #1 cat if it does your CEL will no longer come on. Best of luck!

 

it hits according to more factors than just psi, if it was cold with a TBE and no boost control i can see it hitting fuel cut.

 

By the way, fuel cut could not be mistaken "bogging" in my opinion. Fuel cut feels like hitting a brick wall...

 

defitnetly get a mbc and plug that o2 back..that's what's probably giving you the CEL

 

I am going to order a Forge UNOS and see if I can get in line with Al this weekend at TopSpeed. If I get the flash first and I have this overboost again, the ECU will no longer cut fuel, correct? So I need the MBC to make sure I don't overboost?

 

No. You didn't actually overboost. You just surpassed the the amount of airflow the ECU allows before cutting fuel, and this airflow was caused by a certain level of boost higher than you're used to seeing. Fuel cut will be removed by the flash, but the fuel cut you are hitting is not actually needed - you aren't really overboosting. When you get the flash, if you don't have an MBC yet, then the flash will be controlling the boost and keeping it at 20-21psi anyway, so it's not an issue. The MBC will just give you direct control over the boost, bit it's not an anti-overboost device or whatever.

 

GET RID OF THAT EBAY INTAKE. i had that and my car ran like ****, really cutting up at the high rpms. got the buschur intake, and holly did it make a difference. try putting back your stock intake to see if the same problem persists.
the rear O2 sensor has NOTHING to do with the performance of the car.

 

Fuel cut is more like a momentary loss of power isn't it? You hit it and you loss it for a second then everything is fine. I would not describe it as boggin down. I had some tuning before I put on my TBE. Didn't have the mbc yet, but never hit fuel cut without it.

 

Well I am putting the o2 sensor back on with the mechanical fix. I just sent Al payment for a flash on Sunday. I will get the UNOS, but this week. Hopefully all my problems will be gone this weekend.