Ok I Have An X-OffRoad With The Usual Magnaflow Catback
My Question Is How Can People Talk About "Dumping" Or Completely Taking Off Their Catback System And Leavin It Like That So It Sounds Louder?!?!..
Because When I Got My X From Performance Mustang The First Thing I Did Was Install It!...BIG MISTAKE!...My Car Ran Like Shiii** My Check Engine Light Came On, Overall Big Performance Loss!!..
How Can People Run These Catless Systems Without Their Mustangs Messing Up?!.
You're losing power because of the CEL. The ECU is receiving the same signal from both upstream and downstream O2 sensors so it's interpreting a cat problem. When the ECU sees that problem, it cranks back some timing and fuel. You need a set of MIL eliminators. Once you have those installed, clear your CEL and all will be good.
__________________
Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
You're losing power because of the CEL. The ECU is receiving the same signal from both upstream and downstream O2 sensors so it's interpreting a cat problem. When the ECU sees that problem, it cranks back some timing and fuel. You need a set of MIL eliminators. Once you have those installed, clear your CEL and all will be good.
+1)
Here ya go bud, on sale this month!!! MIL eliminators!!!!!
All you need is two for the rear.
I can't confirm, but what I've read is that the rear O2 sensors aren't used in engine control at all. The front O2s are used to regulate everything, and the rears just monitor cat performance. I believe the CEL is just a light, and that you aren't actually seeing any performance decline because of a computer "compensation". I got the impression from the article that some other cars used the rear O2s for control, but that the modular mustangs don't. Can anyone confirm?
I have a old diablosport predator for My 01 4.6 and the older ones have the option to turn off upstream and downstream O2 sensors and an option to turn off the MIL. works great for Mine with a off-road H pipe and a Magnaflow cat-bat!
I can't confirm, but what I've read is that the rear O2 sensors aren't used in engine control at all. The front O2s are used to regulate everything, and the rears just monitor cat performance. I believe the CEL is just a light, and that you aren't actually seeing any performance decline because of a computer "compensation". I got the impression from the article that some other cars used the rear O2s for control, but that the modular mustangs don't. Can anyone confirm?
What you have heard is somewhat correct. The upstream O2 sensors do provide feedback to the ECU for things like fuel tables. However, if both upstream and downstream O2's are sending the same info, then the ECU determines that as a catalytic converter failure and that triggers a CEL and resulting 'safe mode' of vehicle operation. The ONLY function the downstream O2's provide is catalytic converter performance monitoring.
As for what other vehicles use which set for, I have no clue.
__________________
Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
Ohhh Guysss I Knowww I Have Thosee I Have The Catback And X Installed Since A Long Time!..
Im Just Wondering How Can People Run Offroad X Or H?!...
Without ANY Cats Whatsoever?!.
It's not hard. You just hold your breath when you're stopped with the windows rolled down and yell at the top of your lungs when you're trying to have a conversation.
__________________
Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
What you have heard is somewhat correct. The upstream O2 sensors do provide feedback to the ECU for things like fuel tables. However, if both upstream and downstream O2's are sending the same info, then the ECU determines that as a catalytic converter failure and that triggers a CEL and resulting 'safe mode' of vehicle operation. The ONLY function the downstream O2's provide is catalytic converter performance monitoring.
As for what other vehicles use which set for, I have no clue.
There's a lot opposition on this, apparently. Looks like Mana4Real agrees with you and Randy disagrees:
Quote:
Originally Posted by RandyStinchcomb
Quote:
Originally Posted by Mana4Real
They are all wrong. Yes it will effect the way your car runs. Your car will go into limp mode once the CEL turns on. Once it goes into limp mode your gas mileage will go down and you will be slightly down on power. Spend the 60 bucks on the MIL's... They just have a resistor in them to make the computer believe that there are still cats there. Hence no CEL... If anyone tells you that a CEL doesn't effect the way a car runs, then they need to not be giving advice. cough cough ^^
the above info IS incorrect
O2 monitors which are the ones after the cats ONLY monitor the cats efficieny and in NO WAY will effect the performane of the car and a MIL will NOT always set a car into a "limp mode" thats an old wives tail
"Dumping" Catback 
