E93 330i Decat Issues

[ssamsook]

Hello All, I own a 2008 E93 330i with 45000 km's. I recently decided to mess with the exhaust system and against my better judgement had the cats removed. On idle the car sounded good but it really sounded terrible whilst driving (like an old Toyota / Golf with a freeflow). I then fitted a brand new Schnitzer rear silencer I had kicking around for years with no improvement. I then went to another expert who added two silencers in the middle section and did a software upgrade. The car now sounds much better but my fuel consumption average is around 18 to 19 liters per 100 and around 16 per 100 on the open since. There is also a smell of fuel as if it is burning rich. Can anyone suggest a solution? Should I fit a new branch with cats? Are the silencers the problem? Is the software a problem?

 

[BeemerFanatic]

I think the software is an issue as the exhaust can't change fuel consumption, unless you drive like crazy right foot to hear the exhaust.

Let's see what the forum mechanics say,

 

[zakes27]

HI, i have a 325i.. basically the same setup, if not the same, i only did decat and SW, in low rpms it sound similar to the e46 m3, SW should fix the fuel consumption however i never got that high readings before SW, i suggest start by looking at your manifold and make sure it is not blowing.

 

[Preshen14]

The software is an issue.

Fiddling with the exhaust and cats cannot change the fuel so drastically.

I removed the cats on my E46 330i and used two performance boxes. One in the middle and one is the rear. Sounds perfect.

Did the fuel consumption change when you intially removed your cats or after the recent software upgrade?

 

[AshG108]

the question is now, who did your software? Hopefully it was someone who tuned it for you to sort it out and not try to overfuel the car to push power like on a turbo vehicle.

 

[///Moose]

Could also be one of the sensors, experienced this before on another model

 

[Lizzard]

OP, did you put in cat foolers when you removed the cats? Also think some sensor is causing this over fueling unless the software is trying to manipulate the O2 sensors and cats. The exhaust boxes is just there for noise, well the rear one that is.

OP, does your car make burble sounds the moment you let go of the gas?

 

[sash]

Sounds like a sensor issue to me...