New Exhaust - LOST POWER
05-16-2008, 09:29 PM
#1
New Exhaust - LOST POWER Ok...
I got a maganflow cat back system put on today and I gutted my cats. I put in O2 sims. My car runs 10x smoother. The miss I had is gone, but I have a very noticeable decrease in performance. Whats the deal?
Current mods
TB Bypass
Egr pipe cut
Ported TB
Lid
I got a maganflow cat back system put on today and I gutted my cats. I put in O2 sims. My car runs 10x smoother. The miss I had is gone, but I have a very noticeable decrease in performance. Whats the deal?
Current mods
TB Bypass
Egr pipe cut
Ported TB
Lid
05-16-2008, 09:34 PM
#2
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There's got to be something else going on here. What did you do to fix the miss? Gutting your cats and installing a cat back is not going to fix a miss. It's also not going to decrease you power. Something else happened. Do a once over under your hood and make sure everything is hooked up/not shorted out. Do you have any DTCs?
05-16-2008, 10:11 PM
#3
The hood was never raised at the muffler shop. I watched the whole time. Also one of the cats was in bad shape. It had a bug hole in the ceramic and the screen was gone. You could see through it. The other side looked like it was stopped up with black ****. Maybe one side of the exhaust flowing better than the other was causing the miss?
Another thing. My SES light has always been on. I had the codes read and it said I had bad rear O2's. I disconnected my battery when I got home and the SES light is staying off.
I had a miss in the car the whole time I have owned it up until the new exhaust was put on. Is my problem a PCM "closed loop" or "open loop" problem.
Another thing. My SES light has always been on. I had the codes read and it said I had bad rear O2's. I disconnected my battery when I got home and the SES light is staying off.
I had a miss in the car the whole time I have owned it up until the new exhaust was put on. Is my problem a PCM "closed loop" or "open loop" problem.
05-16-2008, 10:18 PM
#4
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Check your O2s for shorts, put new plugs, wires, and fuel filter on it and see if that doesn't clear it up. If you had a miss before, and that's now fixed, it should have freed up a lot of power, not to mention all that power that should have been freed up by your exhaust mods. Believe me, something's going wrong in there, your mods have zero chance of decreasing power.
05-16-2008, 10:20 PM
#5
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Also, if there's still a hole in your cat, that needs to be fixed one way or another. I really doubt that would cause a noticeable power decrease though.
05-16-2008, 10:29 PM
#6
T6 plugs just put in, along with the wire 1 month ago. I really should change the fuel filter though since I have never changed it. O2 sims are connected good and the leds on them light up. No SES lights.
The hole was in the ceramic inside the cat before they were completely gutted.
Thats what I thought.
Also, if there's still a hole in your cat, that needs to be fixed one way or another.
your mods have zero chance of decreasing power
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05-16-2008, 11:11 PM
#10
If your exhaust freed up a bit, down low you may have lost some torque. I always noticed that with my cutout on my old car open, off the line would feel sluggish, but the gain in the upper rpm was significant.
Could be the same thing, if you aren't bringing it to redline on your butt test and have no dyno/1/4 mile numbers it could just be in your head.
Could be the same thing, if you aren't bringing it to redline on your butt test and have no dyno/1/4 mile numbers it could just be in your head.
05-17-2008, 10:24 AM
#17
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I think the loss in back pressure killed your low end torque. A cam with a low LSA may help. If you do that, might as well change the gearing in your rear end and make more torque.
05-17-2008, 12:39 PM
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and you know after all the hype about stalls i hate to jump on the bandwagon but they are awesome. considering you are not really gaining any HP, (smaller and lighter stall then factory though) i see how anyone could say they are a great bang for the buck on auto cars. makes me not regret i didnt get the M6.
05-17-2008, 01:06 PM
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I think its all in your head. Your essentially stock. If the cars not fast enough throw a cam in there, but there is no way that you would notice a decrease in performance. Sorry, but its all in your head.
Any low end torque you might have lost, will be more than made up for in the top end. Gutting your cats and changing you cat-back will not decrease your backpressure enough to make that big of a difference. I have run open headers for a short time, and even that was extremelly hard to detect from a performance standpoint (easy to detect from a sound standpoint however).
Any low end torque you might have lost, will be more than made up for in the top end. Gutting your cats and changing you cat-back will not decrease your backpressure enough to make that big of a difference. I have run open headers for a short time, and even that was extremelly hard to detect from a performance standpoint (easy to detect from a sound standpoint however).