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Unread 11-05-2013, 04:21 PM   #1
Registered User
2003 TJ Wrangler 
Join Date: Oct 2013
Location: Colorado Springs
Posts: 27
4.0 is super sluggish

I recently bought a 2003 TJ. When I bought it I didn't know that it was severely underpowered until I drove my friends TJ. It has 33's with 4.56 gearing. It had been throwing a P0432 code so I dropped the cat's and there was one that was dislodged and had fallen down. (Pic below) I thought this would fix the problem of it being slow due to the clogged cat, however after replacing this it still has no power. What I mean by no power is that once I hit 2000 rpms there is no more acceleration no matter how hard I push the gas so I always have to shift at 2000 rpms. Does anyone know why this could be? I can't even keep up with guys who have 35's and 3.73s in the mountains.


I replaced all 3 cats and still doesn't feel any different. You'd think id e able to feel a difference since the car was so lodged in there.

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Unread 11-05-2013, 09:06 PM   #2
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1999 XJ Cherokee 
Join Date: Dec 2011
Location: Kingston, ON
Posts: 306
PCM uses the O2 sensors to determine if the cats are bad. When were they last replaced?

When was your last tuneup? Air filter, spark plugs, etc
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Unread 11-06-2013, 07:50 PM   #3
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1992 XJ Cherokee 
Join Date: Oct 2012
Location: umatilla, florida
Posts: 1,960
Does it struggle to get to 2000 rpms? Bucking? Noisy? Drinking gas?
How is it in neutral?
Check the throttle cable with engine off. Look for slack. With engine off use your hand to rotate the throttle on the throttle body. Make sure its opening.
uberxj92 is offline   Reply With Quote

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