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View Full Version : Help!! loosing power

dyna
November 13th, 2005, 08:51
Hey guys. My 95 sport 4.0 HO/auto has been suffering from a degrading power loss. Currently I now have to shift out of OD and nail it to climb the same freeway grade that I used to pull in OD at 80mph. I went back to 235`s just to get my mileage back and power and now its like the 31`s are on it again. It seems to be running the same etc. Can a bad O2 sensor or bad cat cause this?? Theres never been any codes thrown. Also the rigs is bone stock and has 190K on it.
Thanks bunches.
Dr. Dyno
November 13th, 2005, 08:57
Can a bad O2 sensor or bad cat cause this??

Yes they can cause a power loss so you might need to replace both. If your gas mileage has gone down the toilet and you can smell unburnt fuel from the exhaust, replace the O2 sensor first. If you only have the power loss and gas mileage is still reasonable, replace the cat first. You could even experiment by gutting the old cat first.
If replacing one item (or gutting the cat) cures the problem, you've saved some money by not needing to replace the other.
dyna
November 13th, 2005, 10:08
Im all for gutting the POS, but I thought I read of ill results doing so. and yes the mileage is down as well it seems. I also forgot to mention its starting to rattle. Muffler man says Cherokees 4.0s are hell on cats, @ $190 installed,Im a cheap Mofo so Id prefer to do it myself.
Wondered if any of you see any big differences in performance between fill ups at various stations. I can say that every time I get fuel at the Mobil it runs like sheeeeeet, pinging etc. I see the same with my diesel PU, but Im told its normal thru varing Cethane quality.
Thank You..
JAFO
November 13th, 2005, 10:22
See above post for your answer.

Jafo.
langer1
November 13th, 2005, 11:13
Im all for gutting the POS, but I thought I read of ill results doing so. and yes the mileage is down as well it seems. I also forgot to mention its starting to rattle. Muffler man says Cherokees 4.0s are hell on cats, @ $190 installed,Im a cheap Mofo so Id prefer to do it myself.
Wondered if any of you see any big differences in performance between fill ups at various stations. I can say that every time I get fuel at the Mobil it runs like sheeeeeet, pinging etc. I see the same with my diesel PU, but Im told its normal thru varing Cethane quality.
Thank You..
Try unhooking your battery for 1/2 hour or so, it may need to re-learn with the different tires on now.