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Unread 06-12-2013, 05:33 PM   #16
ZeeJay1997
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1997 ZJ 
 
Join Date: Dec 2008
Location: Sweet Home, Alabama
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now that i read the WHOLE post, the cat being welded up may mean it is gutted. the cracker headed will ruin a cat, add a bad O2 sensor to the equation and the cat is a goner.

i would replace the header, or at least do a temp repair to troubleshoot the O2 sensor. The extra air the crack in the header sucks in causes the O2 sensor to report a lean condition to the PCM. The PCM enriches the fuel mixture, causing it to run rich, killing the cat. Of couse, This is all dependent on the health of the O2 sensor, which is an unknown in your case.

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Unread 06-12-2013, 05:46 PM   #17
Badmunky
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1998 ZJ 
 
Join Date: Apr 2011
Location: t, michigan
Posts: 65
Quote:
Originally Posted by ZeeJay1997 View Post
now that i read the WHOLE post, the cat being welded up may mean it is gutted. the cracker headed will ruin a cat, add a bad O2 sensor to the equation and the cat is a goner.

i would replace the header, or at least do a temp repair to troubleshoot the O2 sensor. The extra air the crack in the header sucks in causes the O2 sensor to report a lean condition to the PCM. The PCM enriches the fuel mixture, causing it to run rich, killing the cat. Of couse, This is all dependent on the health of the O2 sensor, which is an unknown in your case.

Right now the ZJ is totally stock. Tires, wheels, every thing. For now any way.

My plan at this point is this:
Replace cracked header with new one. (Not sure what to buy yet, little help here?)
Replace injectors with 703 Neon injectors. (Knew about this and was planing it already.)
Replace up stream O2 sensor. (Current one looks to be stock. Jeep has 152k on it)
Replace failing fan clutch and fan with electric fan from 99 GC, and a fan controller.
Replace drive belt.
Replace TPS.
Do a compression test.
Test fuel pressure.
Check for vacuum leaks.
Change oil and filter.
Service transmission.
Change oil in both diffs and replace leaking cover seals.
Change oil in T-case.
Replace leaking rear wheel seals and install new wheel bearings while I'm in there.
Replace leaking real main seal.
Replace leaking valve cover gasket.
Replace leaking oil pan gasket.
Replace leaking oil filter adapter seal.
Attempt to force the ECU to throw a CEL by unhooking engine temp sensor to be sure that the CEL circuit in the ECU is working. (Have been told Jeeps have a problem with this, and not throwing a CEL or code even when there is a problem.)

And I will look at relocating the AIT sensor as well. Why do people do this?
Where is it now? And will this work okay in extreme cold such as ND in January? Extreme hot such as NV desert in August? I ask because I may move at the end of the year, but I don't yet know where I will be going.


I understand that this thing is not going to do 0-60 in under 6 seconds. LOL
But stock it was rated to do 0-60 in just about 11 seconds. I would be happy with that. Right now I'm closer to 17 seconds, give or take a second.
And passing is just out of the question.

I will admit I am used to driving a much faster car then this is. But I have owned slower cars before. And its not a problem. As long as they run right.

My current DD is a highly moded WRX pushing about 460hp at the crank.
I don't expect the Jeep will ever keep up with it. LOL
But I do expect I can at least keep up with my sister driving a fully loaded Dodge Mini van pulling a trailer!

Yeah she smoked me, her and 4 kids, 2 big dogs, and bunch stuff for my brothers baby shower, PULLING A 1,400lb TRAILER!!!!!!!!!!!!!!!!!!!!!!

She drives like that mini van is a sports car. I was trying to follow her and had to call her and tell her to slow down or she was going to lose me. I could not keep with her in the city, or on the high way. (She was doing like 90mph on the high way with the trailer!!!! Yeah shes nuts!


If what I have planed dos not fix my problem where should go from there?

I have herd that there is a TSB for the ECU not throwing codes. Is this true?

And is there any thing I left off my list that I should just do?


Thanks for the help guys!
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Unread 06-12-2013, 06:44 PM   #18
ZeeJay1997
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Dorman header, NTK O2 sensor.
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Unread 06-12-2013, 07:28 PM   #19
Badmunky
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Quote:
Originally Posted by ZeeJay1997 View Post
Dorman header, NTK O2 sensor.
The Dorman header looks to just be a stock replacement. If I'm going to replace it I might as well go with one that will give me some more power right?
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Unread 06-12-2013, 07:54 PM   #20
ZeeJay1997
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Any power you get from a header will be negligible.

There are no "performance" mods you can do to a stock engine that will be worth the time money you spend on them. No one has proved that the 99 intake and 704 injectors help anything except gas mileage. Upgraded exhaust may help with mileage also.
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Unread 06-12-2013, 08:02 PM   #21
Badmunky
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Well if its going to improve the MPG then I'm good with that.

I would like to get more power out of it thou. Not looking to get 300+hp but 220ish would be nice.

I am used to driving a much faster car. So It would be nice to get a little more power out of this thing.

My cousin is trying to convince me to get a cam and roller rockers. But I don't know. I don't like the idea of putting a new cam in an old motor.
And I really don't have the time to rebuild a motor right now. Or I would have just fixed the XJ I have sitting here with a bad motor in it. LOL.
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Unread 06-12-2013, 08:09 PM   #22
mig1289
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1998 ZJ 
 
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No point in wasting your money caming the 4.0. It isn't meant to get high HP numbers, they get high mileage numbers. Maybe you can look at gearing since it doesn't pick up the way you want.
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Unread 06-12-2013, 08:18 PM   #23
ZeeJay1997
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if you change the cam, the PCM will need custom programming/

i'm with Mig... if it has 355 gears in it, there lies the source of the low torque on the low end.
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Unread 06-12-2013, 09:24 PM   #24
Badmunky
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Well I can look at adding power down the road I guess.
Right now I just need the thing to run right! LOL

It might get a swap next year or something.

I don't have the time right now, but next year I am going to move, change jobs, and that should give me more free time.

Might do an LS1 or something.

Right now I'm just going to focus on getting running right. It seemed to run good right after the tune up, then went back to no power the next day. It has to have a bad sensor.
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Unread 06-12-2013, 10:10 PM   #25
mig1289
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If def rock an ls engine in a Jeep. That would be sick with built 6speed
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Unread 06-14-2013, 02:39 PM   #26
Badmunky
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All my image links failed. They have all been fixed.
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Unread 06-14-2013, 07:29 PM   #27
Badmunky
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I'm going to order header for it next Thursday after I get paid.

Right now I have it down to these headers:
OBX. (I have run them in the past with no problems and they have a life time warranty)
APN. (Don't like the way they route the #6 primary as it will hit the intake manifold on the 99+ GC and I am changing to that IM when I do the header. So if I run this one I will need to cut the header up to fix the problem.)

Other. Recommend something.
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Unread 06-16-2013, 10:16 AM   #28
Badmunky
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Ok so last night we drove the Jeep 8 miles to the movies.
For no reason (I have not changed any thing yet.) its back to running great! Its got good power, and I was even able to pass a slower car with no problems.

It still tries to stall, stumbles, and backfires a minute or so after a cold start. And the problem seems to be getting worse. It now dose this even if the motor is still worm. And the stumble/ hesitation/ stall/ backfire is lasting longer before it sorts its self out.

Also last night after the movie on the way home I floored it from a stop to see how long it would take to get to 60. It did much better then the 17 or seconds from the last time. Took it about 12-13 seconds. (Still a little slower then it should be.) But the trans did something I was not expecting. At full throttle its shifting out of first gear at 4,000rpm. I thought it should hold to close to 5,000rpm?
Is this normal?
I checked the trans cable. It is adjusted correctly. The trans is due for a service. The fluid is a bit darker then it should be and smells a little burnt. I am going to have the service done on it the next time I get home around the 4th of July. Until then it will not be driven much.

I don't know much about autos. This is really the first one I have owned as an adult. (Had a few beaters when I was a kid that never lasted long.)
I have been driving manual trans cars for the last 15+ years. (Could not find a manual Cherokee that was not rusted out, so we settled for the ZJ.)

Thanks guys for the help!
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Unread 06-16-2013, 11:59 AM   #29
dnuccio
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Burnt smelling fluid is not good. Trans might be on its way out. All you can do is change the fluid and hope for the best
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Unread 06-16-2013, 01:51 PM   #30
Badmunky
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Originally Posted by dnuccio View Post
Burnt smelling fluid is not good. Trans might be on its way out. All you can do is change the fluid and hope for the best
Yes I know. I did not check it before I bout it

But my moms truck had near black fluid in it and was vary burnt smelling when we changed it 2 years and 40k ago and its still going strong. So you never know really. It depends on haw badly the PO beat on it.

Also it is now shifting at around 4,700rpm. I think the TPS is going out on it.

I changed to the Accel cap and rotor today. Made it run much better. The old one had been on there for about 250 miles and was already burnt a bit.
I think the rotor was bad from new.

It runs better now. Still not where it should be but getting there.
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