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Semper Fidelis
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4,541 Posts
Discussion Starter #1
Anyone here experienced enough to adjust the ECU to allow for a larger diameter exhaust, therefore decreasing the back pressure? I am trying to keep from ruining my fuel economy.
 

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hoo dat. wat.
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21,594 Posts
what vehicle?

getting rid of converters?

If you have 02 sensors, the ECU should adjust just fine.
 

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Semper Fidelis
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4,541 Posts
Discussion Starter #3
Planning on a total overhaul of the exhaust. Hedman Tuned Headers, no cats, flow pro mufflers all the way back, true duals, with exhaust dumps and eletric cutouts. Oh, and getting rid of the stock 2 1/4" and going 3 inch. Maybe. Still in planning stage.
 

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hoo dat. wat.
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21,594 Posts
Planning on a total overhaul of the exhaust. Hedman Tuned Headers, no cats, flow pro mufflers all the way back, true duals, with exhaust dumps and eletric cutouts. Oh, and getting rid of the stock 2 1/4" and going 3 inch. Maybe. Still in planning stage.
WHAT VEHICLE? :sonicjay:
 

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Semper Fidelis
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4,541 Posts
Discussion Starter #5
oh,the big hoe (tahoe).
 

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hoo dat. wat.
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Doh! What year? If you have rear 02 sensors, I would highly recommend high flow cats to keep your OBD system happy - also helps alot if you don't want to choke sitting at idle. :d:
 

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More boost than yours:)
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1,252 Posts
The issue is not the backpressure, as far as I know. It's just the rear o2 sensors. I believe you can buy O2 simulators to fool the ecu into thinking that the cats are doing their job. The front cats you want to keep as they actually provide fule mixture feedback into the ecu.

Of course, there are many that know better than I. I'll shut up now. :)

Good luck.

PM
 

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hoo dat. wat.
Joined
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21,594 Posts
The issue is not the backpressure, as far as I know. It's just the rear o2 sensors. I believe you can buy O2 simulators to fool the ecu into thinking that the cats are doing their job. The front cats you want to keep as they actually provide fule mixture feedback into the ecu.

Of course, there are many that know better than I. I'll shut up now. :)

Good luck.

PM
It's not the front cats that provide the feedback - it is the front 02 sensors, but I think you meant that. :)
 

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More boost than yours:)
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1,252 Posts
It's not the front cats that provide the feedback - it is the front 02 sensors, but I think you meant that. :)
Yep. I can't type as fast as I'm thinking . . .
 

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Resident HVAC/R Jambi
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10,938 Posts
I think it is funny how people think putting big exhaust in gives uber fuel milage :sonicjay:
 

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More boost than yours:)
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1,252 Posts
It'll help some, but generally more in the higher throttle % driving. Which is not exactly the way to get better MPG. Then engine will get better BSFC (generally speaking) because of fewer pumping losses, but at WOT you're not getting the best fuel mileage anyway.

You can free up some power though :thumb:
 

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Semper Fidelis
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Discussion Starter #12
Thanks- I am not doing this because I think my fel economy will improve, I like loudness. But I know you can ruin MPGs if you have decreased back pressure. I also have O2 Sims which I will put in, but the main question I am asking is about ECU reprogramming. I am interested in resetting my fuel trims if the back pressure is decreased.
 

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Premium Member
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4,562 Posts
Thanks- I am not doing this because I think my fel economy will improve, I like loudness. But I know you can ruin MPGs if you have decreased back pressure. I also have O2 Sims which I will put in, but the main question I am asking is about ECU reprogramming. I am interested in resetting my fuel trims if the back pressure is decreased.
what year hoe?
 

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Semper Fidelis
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Discussion Starter #14
:sonicjay:Did you call me a hoe?

1998
 
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