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post #1 of (permalink) Old 01-29-2003, 05:10 PM Thread Starter
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Jeep power loss am I missing something here??LONG

For those of you who don't know:

In eairly December I had a big top end power loss in my 97 TJ
I changed plugs, cap,rotor, cleaned the fuel system, and tightened the exaust. I gained some of the power back, but not all of it.
I was running 31 inch tires with no problems. Late December (Power problem already an issue) I added 32-11.50 tires and a 3" lift. no change in power, still lacking but it did not go south after the tires were instaled.

Now the power continued to lessen. The jeep will hardly run 60 mph and that is only if I run the tach to About 3400 before changing each gear. Verry little power in 5th gear. When in 4th and fifth gear I find that at about 60 mph I can put the pedle on the floor and nothing happens.

The exaust sound has changed to make it sound like it is pulling hard.

I know that my front berrings are bad (messed up by a mechanic installing r&p seal) I am preparing to replace them which leads me to a decision

I think the cat is clogged. Crysler says there is nothing wrong with it. Actualy they told me they hit it with a mallet and it sounded fine?? Great diagnosi eagh??

The other option is to go to lower gears when I replace the berrings.

I cannot find any cracks in the exaust manifold, and fuel rail pressure seems to be ok.

My question is what do you recomend, and does it sound like I am missing anything??
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post #2 of (permalink) Old 01-29-2003, 05:16 PM
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Re: Jeep power loss am I missing something here??LONG

1. Pull the O2 sensor and go for a ride.
2. If the cat's plugged...
3. This dumps the backpressure in the exhaust manilford and,
4. The power will be restored.
5. Banging on the Cat with a hammer just tells you if things are loose,
6. Which often are,
7. But not plugged...
8. You should be able to have a muffler shop measure the backpressure
9. At the tailpipe..
10. That's antother indicator.
12. My guess is that the exhaust manifold is glowing a dull red!
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post #3 of (permalink) Old 01-29-2003, 05:26 PM
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Re: Jeep power loss am I missing something here??LONG

Part of your tune-up should include a new O2 sensor as a bad one could result in a loss of fuel economy and
power. If you decide to replace the cat, use a Random Technology one, as they are very good pieces
and are usually cheaper than the ridiculously over priced factory units.

Chris
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post #4 of (permalink) Old 01-29-2003, 05:27 PM Thread Starter
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Re: Jeep power loss am I missing something here??LONG

I cannot catch the manifold glowing. I tried to remove the o2 sensor, and it is stuck tight, I am soaking it with some penatrating oil. Wont the sensor being out cause it to run rich??
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post #5 of (permalink) Old 01-29-2003, 05:42 PM
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Re: Jeep power loss am I missing something here??LONG

</font><blockquote><font class="small">In reply to:</font><hr />
I cannot catch the manifold glowing.

[/ QUOTE ]1. Lift the hood at night... in a dark area...
2. If there is back pressure the heat can't escape and heats up the exhaust manifold.
3. Believe me... if you've ever seen one do this... you'll never forget it.</font><blockquote><font class="small">In reply to:</font><hr />
I tried to remove the o2 sensor, and it is stuck tight, I am soaking it with some penatrating oil.

[/ QUOTE ]4. Good... if you buy a sensor removal socket...
5. Make sure it's a good one!
6. The bottom's tend to spread and it does no good.
7. I prefere a nice big box wrench and a Pipe (if there's room).</font><blockquote><font class="small">In reply to:</font><hr />
Wont the sensor being out cause it to run rich??
a. I like PBBlaster or
b. BreakFree,
c. Put some anti-seize compound on the threads at re-install.

[/ QUOTE ]8. Yes, it will, but...
9. You're not going to drive it all over town...up and down hills for a day or two...
10. You're just driving it to see if power's been restored.
11. Then replace it.
12. A couple of miles, or less, of driving and you should know.
14. It avoids what a lot of shops do...
15. Take a screwdriver and punch a hole in the Cat Converter...
16. Then plug it with a screw.
17. Later the screw drops out because the hole has opened due to rust.
18. Induced by the punch.
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post #6 of (permalink) Old 01-29-2003, 05:58 PM
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Re: Jeep power loss am I missing something here??LONG

Have you had your sensors checked out? I was reading about TPS sensors the other day, and someone mentioned that the sensors can lose their base line. Sensors don't necessarily die suddenly.
post #7 of (permalink) Old 01-29-2003, 06:32 PM Thread Starter
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Re: Jeep power loss am I missing something here??LONG

Got the o2 sensor out. It definately goes through the paces better reaches 55-60 quickly like it used to. While 60 is not the top end like it was with the sensor in, it is still sluggish around the 60mph mark, but maybe I have been fooling with this problem ling enough that I forgot what it was like before. Definate inprovement with the o2 sensor out.
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post #8 of (permalink) Old 01-29-2003, 06:32 PM
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Re: Jeep power loss am I missing something here??LONG

well i all i can say is that when i had my 95 Yj, 2.5L stick, with 32x11.5 BFG MT's, after the speedo change, have u done that? using 5th was pretty much out of the quesiton, 4th was usedd always, and i tried to lighten the load as much as possble, even taking off the spare tire if it was on a long trip, just make your minds not playing tricks on you, ,and make sure u get that speedo changed that will help u actually know how fast u are running compared to your rpms, i always ran mine up to about 2700 rpms before shifting, its a 4 cly, ,its not gonna move like a race car, your power loss could be because of a BAD 02 sensor, instead of pulling it out, just try unpluging it and see if it runs any worse, it should, and if it doesn't tahts your problem, i would serously regear, but then your gonna get stuck in my dilemma, but then i decided to sell the jeep, do i go with 4.88's or 4.56;s hum.. decisions decisions... and for some reason i noticed a big difference in losing some grunt power between going from 31's to 32's even tho there is't that much of a differnce....hope this helps!
post #9 of (permalink) Old 01-29-2003, 06:42 PM Thread Starter
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Re: Jeep power loss am I missing something here??LONG

wrangler88

The jeep ran fine without the sensor, then under load it spit and sputtered but then quickly recovered and ran better than it has in months. Does that meadn the o2 sensor is bad??

I have not replaced my spedo gear, how far off will it be?

also What decision did you make on the gears?? I think if I change I want to run 4.88, but Will that still give me 65-70 mph on the interstate?

Also wierd thing I am getting about 14 mpg. that does not seem that bad concidering the lift and the tires
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post #10 of (permalink) Old 01-29-2003, 06:52 PM
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Re: Jeep power loss am I missing something here??LONG

1. IMHO... the Cat's plugged, it's not the 02 sensor.
2. I'll let others comment on the running gear...
3. I'm still learning about that stuff...
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