Help please! no power , check engine light blinking under hard accel! - Page 3 - JeepForum.com
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Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > Help please! no power , check engine light blinking under hard accel!

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Unread 02-20-2013, 07:44 AM   #31
zjosh93
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1993 ZJ 
 
Join Date: Aug 2010
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Not sure on the 5.9 but on the 4.0 you can just loosen the nuts at the header flange and let the exhaust hang a bit. Take it for a short test drive and if your power comes back it's probably the cat. The three bad cats I've seen were all sudden failures. One melt down on a GM car and two Jeeps where the front honeycomb fell apart and lodged against the rear catalyst. Welded in universal cats; one has about three years on it and the other about two with no additional failures.

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Unread 02-20-2013, 04:33 PM   #32
ZeeJay1997
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You can also drill a few half inch relief holes in the fwd convertor flange to test. Of course, be prepared to weld them back up if it's not the problem
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Unread 02-20-2013, 05:21 PM   #33
zjosh93
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If you have a welder and the skill to use it it's easier to cut the pipe in front of the cat to inspect the catalyst and reweld it than to try and fill 1/2" holes with weld. If the cat is plugged you're going to have to cut it out anyway.
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Unread 02-20-2013, 09:52 PM   #34
Rodney88
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Once i get a chance to get to the muffler shop im going to throw a new exhaust on it, and replace the cat, the cat was rattling really bad, not any more however, witch makes me suspect the cat is damaged and/or clogged. I did not go through any water with the jeep so i guess that's out of the question. The same thing happened on another vehicle of mine, (same symptoms as my jeep, and it was a clogged cat.) Im also going to look into the misfire, as i need to give the 5.9 a tune up any ways, ill keep you guys posted when i have more info. Thanks for the help!
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Unread 02-21-2013, 06:10 AM   #35
ratmonkey
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A plugged cat will cause a misfire. Fix the exhaust first then see what else is going on.
Doesn't need to be water to damage the cat, I rarely see that happen, But often see damage from rocks and stumps
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Unread 02-21-2013, 10:04 AM   #36
Uniblurb
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If you're going to replace the whole exhaust think I'd be doing it myself instead of going to some rip-off muffler shop. It's easy enough to remove the whole exhaust with just 2-3 cuts of a sawz-all or a torch if you have one. Then you can buy the higher quality parts you want depending on the sound/flow you're looking for. Plenty of threads around here on exhausts. If you want it welded together then clamp it temporarily and take it to a shop or better yet find a friend with a welder. You'll still be saving $ and be much happier with a higher quality exhaust. Good luck.
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Unread 02-26-2013, 11:01 AM   #37
jnowak
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Any news or progress
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Unread 04-02-2013, 04:32 PM   #38
Rodney88
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Yes, took it to the exhaust shop today, picking it up in a couple hours. The guy at the exhaust shop within 2 mins said the cat was bad, so i put a aftermarket muffler and a new cat on. Ill be driving it shortly, so I am pretty sure the cat failed. Sorry for the late reply, the jeep is not my daily driver. If the cat is not the problem I will let you guys know!
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Unread 04-02-2013, 07:54 PM   #39
Rodney88
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1998 ZJ 
 
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ok, so the cat was indeed the problem, the thing runs great now. The exhaust is not bad either Thanks for the help again guys!
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