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ya im running my stock cat on there so its street legal its only 1990 and i just passed emissionOriginally Posted by tandersen45
That definately sounds like a lack of backpressure. Are you running any sort of cat????
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Most people dont realize that when you add mods to a vehicle that drectly interfier with OEM specs, it will show poor results. Becuase your vehicle is comparing readings from previous start up to a new different spec. Resulting in poor performance..
so my point today is reset ur ecu and the come down to a final
conclusion..
Originally Posted by 98jeepsrt6
For those that are not impressed with there slightly larger exhaust setup, have you considered resetting the Ecu to relearn your new system.. The o2 sensor will provide the ECU correct A/f reading from the new system and reprogram itself to add more fuel = to the amount of air flowing through the system.. That would be the purpose of the all the sensors in the vehicle each playing its part to learn what the engine is doing and how to make it run/perform most efficiently. Most people dont realize that when you add mods to a vehicle that drectly interfier with OEM specs, it will show poor results. Becuase your vehicle is comparing readings from previous start up to a new different spec. Resulting in poor performance..
so my point today is reset ur ecu and the come down to a final
conclusion..
How do i reset my ECU
Member
Just sold 92xj with 215k had magnaflow hi flow cat. also intake and performance muffler all pipes were stock sizes never experienced problems like yours in fact pulled up hills like a dandy now with my 2000xj bought in July which has obd2 I dont see myself doing all that because I sort of like guiet better besides the po had muffler and tailpipe replaced I dont know brand of muffler but its sounds diff. than other xjs I hear I am content for now. PS I did not reset ecu on the 92 your 90 is probably not a HO motor and might not do well with the upgrades you did sorry dont how to reset ecu maybe you might have other gremlins testing your sanity
Senior Member
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https://www.cherokeeforum.com/f2/jee...ocedure-46047/Originally Posted by oneal916
How do i reset my ECU
Senior Member
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o2 sensor, seems like your running rich..Originally Posted by oneal916
also i noticed it was back firing too today
question you think if i went back to the stock pipeline that would mainly sovle my back fireing problem . cause what happen with my stock exshuast is back in highschool me and my metal shop teacher welded the pipeing to the muffler so it wouldnt move and when we took it off his welds looked like some bird crap on it . and the was a small hole pushing alot of air out the back . most likley it was my fault for wheelin
CF Veteran
Proper grammar helps 
But yes if you go back to stock exhaust pipe size, you wont get the backfiring. Its due to the lack of back pressure, which is good for torque motors like ours
But yes if you go back to stock exhaust pipe size, you wont get the backfiring. Its due to the lack of back pressure, which is good for torque motors like ours
Senior Member
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Originally Posted by oneal916
question you think if i went back to the stock pipeline that would mainly sovle my back fireing problem . cause what happen with my stock exshuast is back in highschool me and my metal shop teacher welded the pipeing to the muffler so it wouldnt move and when we took it off his welds looked like some bird crap on it . and the was a small hole pushing alot of air out the back . most likley it was my fault for wheelin
Have your tried to reset the computer yet??
Do you have CEL on for o2 sensors??
Yes going back to factory would solve you "backpressure" porblem... but then that takes away from having a nice exhuast..
I think the stock exhaust manifold creates enough backpressre because of the poor design but thats my opinion.. Try to fix the other small probs and see how it turns out before you go swapping everything out..
does your back fire sound like this??
Seasoned Member
what you lose is torque and torque is your take off power. Opening up the exhaust is for gaining upper rpm horsepower. How many of us want to sacrifice take off power and bottem end grunt for sound and high rpm hp? I know I don't often pass 3500 rpm with mine and I run hiway speeds every day.
CF Veteran
i think youve got other problems besides having to big of pipe, im running 2.5 inch all the way back from the down pipe, with no cat and a flowmaster 40 and mine runs sooo good, great power, great sound, never had any loss of power what so ever, i also have an air intake and i tuner though so that could be it, but it ran fine without the tuner, try resetting your ecm and if that dosent help check all the connections at the throttle body and see if anything is bad up there
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ya i agree but i loved both so im just going to go back to stock pipe . on the freeway it gets up and takes off with the new exshaust but i don't like it lugging just to get up to 25 and 35 mph. i like that torque back so i could go up hills and not be pushing 3000 rpms to make itOriginally Posted by mcssls
what you lose is torque and torque is your take off power. Opening up the exhaust is for gaining upper rpm horsepower. How many of us want to sacrifice take off power and bottom end grunt for sound and high rpm hp? I know I don't often pass 3500 rpm with mine and I run highway speeds every day.