i think to big of exhaust
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Joined: Mar 2010
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From: steilacoom washington
Year: 1990
Model: Cherokee
Engine: striaght 6 4.0l
Thread Starter
Seasoned Member
Joined: Mar 2010
Posts: 290
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From: steilacoom washington
Year: 1990
Model: Cherokee
Engine: striaght 6 4.0l
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..
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
Joined: Jul 2010
Posts: 182
Likes: 1
From: nanticoke pa
Year: 2000
Model: Cherokee
Engine: 4.o
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
Last edited by kemjeep; Oct 31, 2010 at 09:33 AM.
Senior Member
Joined: Mar 2010
Posts: 718
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From: Miami,Fl
Year: 1998
Model: Cherokee
Engine: 4.0 L6 Srt
Thread Starter
Seasoned Member
Joined: Mar 2010
Posts: 290
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From: steilacoom washington
Year: 1990
Model: Cherokee
Engine: striaght 6 4.0l
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
Joined: Jun 2010
Posts: 2,501
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From: Flint/Asheville
Year: 1995
Model: Cherokee
Engine: 4.0 HO
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
Joined: Mar 2010
Posts: 718
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From: Miami,Fl
Year: 1998
Model: Cherokee
Engine: 4.0 L6 Srt
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??
Last edited by 98jeepsrt6; Nov 2, 2010 at 07:47 AM.
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Joined: Nov 2009
Posts: 421
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From: Rio Rancho NM
Year: 1996
Model: Cherokee
Engine: 4.0
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.
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Joined: Sep 2009
Posts: 1,092
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From: Chesapeake, Virginia
Year: 2002
Model: Grand Cherokee
Engine: 4.7
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
Thread Starter
Seasoned Member
Joined: Mar 2010
Posts: 290
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From: steilacoom washington
Year: 1990
Model: Cherokee
Engine: striaght 6 4.0l
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.