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Unread 11-12-2009, 07:46 AM   #16
RebuildRookie
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I think your right about on the side. If my memory serves me correctly. i will check at lunch to verify.

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Unread 11-12-2009, 07:47 AM   #17
Que89YJ
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Coolant temp sensor is on the intake on our 2.5L. Post catalyst burn is it running too rich and if it is seconds after you shut off. I know youve done a bunch of work on the heap after the hours we spent troubleshooting over the phine. There are maybe 3 things I can think of with everything youve done. 1) Cracked header or egr tube leak on the exhaust manifold. It will throw off the O2 sensor. 2) engine temp sensor. It will cause the PCM to think it is still in warm up and go rich on the Fuel/air 3) Bad O2 sensor. You could also be timed a little off too. Good to see your heep is mobile again.
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Unread 11-12-2009, 07:55 AM   #18
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Quote:
Originally Posted by Que89YJ View Post
Coolant temp sensor is on the intake on our 2.5L. Post catalyst burn is it running too rich and if it is seconds after you shut off. I know youve done a bunch of work on the heap after the hours we spent troubleshooting over the phine. There are maybe 3 things I can think of with everything youve done. 1) Cracked header or egr tube leak on the exhaust manifold. It will throw off the O2 sensor.

Hope its not cracked, cause I just put a new to me one on it. but I will check it again

2) engine temp sensor. It will cause the PCM to think it is still in warm up and go rich on the Fuel/air

Original is still installed. Guess replacing it wouldnt hurt.


3) Bad O2 sensor. You could also be timed a little off too. Good to see your heep is mobile again.

Using the O2 sensor off of the exhaust manifold I bought off of a part out. did look pretty good on inspection, but havnt tested it yet.

Actually its running really good. I have actually been passing people on I-55 The "poof" backfire only happens after running it for a while and the engine is at optimal running temp. If I shut it off as soon as I park it, I get a bigger "Poof". If I park and wait about a minute it is a smaller "poof".

Still greatful for your help and still working on sending you a case of "Souther Pecan"
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Unread 11-12-2009, 07:56 AM   #19
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Also, I did notice the air tube thing coming off of the exhaust manifold and goes back to the air filter box, looks kinda like a small dryer vent, is loose and full of taped up holes and tearing, could that be a cause also.
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Unread 11-12-2009, 08:35 AM   #20
5.7YJ
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That could be part of the problem, it's allowing fresh o2 into the exhaust. When you shut off your Jeep, it's blending with any unburnt fumes and allowing some combustion. It would be an easy repair to try.
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Unread 11-13-2009, 06:25 AM   #21
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Alright, the CTS has a male connector and the MAT has a female connector. The CTS is on the end of the intake manifold pointing towards the brake booster. I did not install a new one, but I had one lying around from a used exhaust/intake manifold I bought as a replacement. Pulled the currently installed one and it had build up on it pretty good. I put the extra under the bench grinder/wire wheel and wire wheel cleaned the end carefully. Shining like new. Drove to work this morning engine was up to running temp (210) parked it shut it down and still had a "poof" but alot softer than it has been. Temp outside this morning was 41 so I will check for the "poof" again when I get home after work.

If its still there I will try to change that hose under the air box when I get back from TN. this sunday.
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Unread 11-13-2009, 06:39 AM   #22
Que89YJ
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Do a reset on the battery too. The calibration memory reset will clear and you start from a clean slate. Tn. this weekend? going to east or west side?
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Unread 11-13-2009, 06:50 AM   #23
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Central- just past Jackson, TN towards Nashville, a place called Wildersville. Got a Cabin on one of the lakes there for the weekend. I am a lucky fella, my wife asked me last night while laying in bed "can we take her" I said who and she said "the jeep".

I wish it was ready for that long of a trip. Maybe this spring.

I will let it reset this weekend.
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Unread 11-13-2009, 06:56 AM   #24
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Thats great. I spemd time over in the Newport area. Its beautiful through there and definitely Jeep 4x4 country. Enjoy yourself. Its gun season opening this weekend and my heep isnt ready yet either. Next spring maybe we can meet in TN and tear it up a bit. My GF is liking the heep more and more. I think its because she gets my Charger RT when I drive the Jeep. LOL. Enjoy!
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Unread 11-17-2009, 01:02 PM   #25
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Took the CAT off last night and decided to look in it. There was nothing, it was hollow. Is that normal? I thought there was suppose to be some sort of honeycomb thing in it.
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Unread 11-17-2009, 02:44 PM   #26
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Here's a bad one


Here's a better one


Hope this helps!
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Unread 11-18-2009, 06:43 AM   #27
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Sounds like the PO gutted the cat.
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Unread 11-18-2009, 07:02 AM   #28
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I am the PO haha. I think that it gutted itself. It was running way rich and backfiring so bad that it blew several mufflers (over the last several years). So I think thats what happened.

Last night I cut the cat out (but left the mounting plate for future use). Installed new exhaust (Cherry Bomb Turbo) sounds good, but when I arrived at work this morning still got the "poof".

Gonna change out the exhaust manifold to air box hose this week when I find one at a parts store.
Anyone know where to find one?
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Unread 11-18-2009, 10:36 AM   #29
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The MAT (or Air Charge Sensor) is located on the top of the intake manifold. In approximately the same location (fore to aft) on the side of the manifold is the CTS. The 88 & 89 2.5 did not have an open port on the water neck for the CTS. When it's cooled down, reach under your intake and feel around. It's pretty easy to find if you're looking for it.
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Unread 11-18-2009, 11:10 AM   #30
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Thanks, I found the CTS the other day and replaced it, still no luck still getting the "poof"
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