Unbolting the exhaust made a world of difference... Why?

[edricci]

My 03.5 MSP has intake, fmic, motor mounts, bov, etc. and stock exhaust... I ran a 15.2 in the 1/4 wtf?? I unbolted the exhaust after the J pipe and now the car is no joke twice as fast. Is this normal? It always felt "flooded" when I floored it but now with exhaust off it EATS!!! I am planning on getting Vibrant thursday so hopefully my problem is solved.

 

[yudkib]

the stock exhaust necks down to a 2" midpipe. mystery solved. you also might have been running a little lean (well lean-er) with no downstream O2 sensor

 

[repthemazdas]

so with no 02 ssensor ur car car will run better?

 

[HighSpeed]

the stock exhaust necks down to a 2" midpipe. mystery solved. you also might have been running a little lean (well lean-er) with no downstream O2 sensor

Leaner? I would think that the computer would read too much air, or not read the sensor at all(depending if it is still connected) and would go into a safe fuel map which would run richer?

 

[thecrash91]

downstream doesnt affect performance, i thought it was upstream

 

[disturbedfan121]

i had my primary o2 not reading right, i got only 25mpg to my now 30mpg with it fixed, but the car felt more responsive and no hesitation.

 

[slavrenz]

downstream doesnt affect performance, i thought it was upstream

Correct - the rear o2 sensor has no effect on your afr's. It only monitors the performance of your cats.

 

[thecrash91]

Correct - the rear o2 sensor has no effect on your afr's. It only monitors the performance of your cats.

twas what i thought.

 

[HondaEat-R]

Because catalytic converters and 2" piping is ghey.

 

[edricci]

my second o2 sensor is before the cat?? my car constantly throws codes for low catylyst pressure or something like that...

 

[HondaEat-R]

That 2nd sensor needs to be after the cat, AKA downstream.

 

[Bassmachine]

This thread makes me laugh. Of course it ran better, when you have a turbo its all about getting the exhaust gases out of the way as fast as possible. The stock exhaust is crap, like they said it necks down to 2in which should be illegal on a turbo car i dont care if thats what the factory put on it.

 

[NocturnalSpeed]

(sad2) Maybe thats why the car feels like hits a wall when I give it gas. I have 3 of those converters under my speed and just found out it's a 2" pipe.

I was stupid for messing with a STI (unamused).... hey he was deep 4 people.

Pope's downpipe can't come any sooner.

 

[yudkib]

you musta gotten spanked up down and two ways from sunday.

 

[NocturnalSpeed]

you musta gotten spanked up down and two ways from sunday.

haha, we didn't even hit at the same time. We both shifted into 2nd slowly and the rpm's were getting higher and I jumped it. Hit 3rd and the car just choked after that, so I let off because I know I had no chance anyways.

I'll have my fun soon. Just need to stay patient and continue counting the days...

 

[edricci]

I have a 3" Vibrant system on the way hopefully it flows as good as open exhaust or at least good enough to not feel like I am pulling a trailer!!! I'll post how things work out. Thanks for all the info...