Catalytic converter/engine compression - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 03-18-2012, 03:39 AM   #1
Jeeper
 
Join Date: Mar 2012
Posts: 18
Angry Catalytic converter/engine compression

i own a 92 jeep renigade with straght 6, with 231j gear, 35 inch mickey thompson tires and no lift and 138000 miles, brand new boshch platinum 2 spark pugs, new wires, new rotor and rotor cap,, just replaced engine oil with mobil, replaced both tranny and transfer case oil,,gives about 10-12 mpg the problem that i am having at this point it that jeep works fine until 3rd gear, when i go to 4th gear i feel loss of power just a little bit when i shift from fourth to 5th gear around 2.25 rpm and above 50 miles the speed starts decreasing to 45 and it just gets stuck there. i just doens't go above that and a 1.5 rpm even with full accelerator..im assuming it's caused by bad engine compression or bad cat converter.. i haven't gotten the compression checked yet but will get that asap.. and ideas why it's going on...

deepak is offline   Quote Quick Reply
Old 03-18-2012, 08:51 AM   #2
Jeeper
 
Beachcruiser's Avatar
 
Join Date: Feb 2012
Location: Raleigh, NC
Posts: 429
The cat is definately a suspect, compression is easy to check, but 35s w/ stock gearing is going to kill your top end too...

Beachcruiser is offline   Quote Quick Reply
Old 03-18-2012, 08:51 AM   #3
Jeeper
 
Gkrynick22's Avatar
 
Join Date: Feb 2012
Location: Marlborough, CT
Posts: 84
I don't think a bad cat would cause those symptoms. If your cat was bad the jeep wouldn't rev properly and would lose power no matter what gear you were in. Some times a clogged cat won't show its symptoms until it warms up. I would check the compression.
Gkrynick22 is offline   Quote Quick Reply
Old 03-18-2012, 10:04 AM   #4
Jeeper
 
Master4th's Avatar
 
Join Date: Mar 2012
Posts: 341
Hows your clutch, do you smell anything when this happens?
Master4th is offline   Quote Quick Reply
Old 03-18-2012, 12:21 PM   #5
kik
Jeeper
 
kik's Avatar
 
Join Date: Dec 2008
Posts: 4,796
Images: 1
Quote:
Originally Posted by Gkrynick22 View Post
I don't think a bad cat would cause those symptoms. If your cat was bad the jeep wouldn't rev properly and would lose power no matter what gear you were in. Some times a clogged cat won't show its symptoms until it warms up. I would check the compression.
I'm going to have to partially disagree on this. When the cat on my 89 4.2 5 spd. was clogged it ran fine with no problems until it got to about 40-50 mph when you would be in 4th or 5th gear. At that point it still ran fine except that it "dogged". No additional power even when you pushed it to the floor. And, it basically died in place going up hill. Changed the cat and everything was back to normal.
kik is online now   Quote Quick Reply
Old 03-18-2012, 01:59 PM   #6
Jeeper
 
Join Date: Mar 2012
Posts: 18
i put brand new clutch.. and by top end im sure you are referring to head, valves, and rings?
deepak is offline   Quote Quick Reply
Old 03-18-2012, 02:01 PM   #7
Jeeper
 
Join Date: Mar 2012
Posts: 18
and sugggestions about gas mileage?
deepak is offline   Quote Quick Reply
Old 03-18-2012, 02:48 PM   #8
Jeeper
 
Beachcruiser's Avatar
 
Join Date: Feb 2012
Location: Raleigh, NC
Posts: 429
I'm not sure how you are fitting 35s on a no lift YJ (unless the fenders are trimmed a LOT)...but if you have the stock gears your mileage is probably going to suffer a bit as more throttle will be needed to get you away from a dead stop. You could swap in 4.10 gears from a 4-cylinder Jeep for pretty cheap. It won't get you to 20MPG, but combined w/ easy driving, it would probably help.

Big tires & good gas mileage don't really go together.
Beachcruiser is offline   Quote Quick Reply
Old 03-18-2012, 05:30 PM   #9
Jeeper
 
Master4th's Avatar
 
Join Date: Mar 2012
Posts: 341
Quote:
Originally Posted by kik View Post
I'm going to have to partially disagree on this. When the cat on my 89 4.2 5 spd. was clogged it ran fine with no problems until it got to about 40-50 mph when you would be in 4th or 5th gear. At that point it still ran fine except that it "dogged". No additional power even when you pushed it to the floor. And, it basically died in place going up hill. Changed the cat and everything was back to normal.
Ditto on that, same thing happened to me accept eventually the chunk that was clogging totally clogged my exhuast and it was like the engine was working way to hard but I wasnt going anywhere.
Master4th is offline   Quote Quick Reply
Old 03-18-2012, 07:54 PM   #10
Jeeper
 
Gkrynick22's Avatar
 
Join Date: Feb 2012
Location: Marlborough, CT
Posts: 84
Quote:
Originally Posted by Master4th

Ditto on that, same thing happened to me accept eventually the chunk that was clogging totally clogged my exhuast and it was like the engine was working way to hard but I wasnt going anywhere.

I stand corrected, twice. I have never seen a clogged cat that didn't have an effect in every gear. It's good to know though. Did you get a chance to check the compression?
Gkrynick22 is offline   Quote Quick Reply
Old 03-19-2012, 01:46 AM   #11
Jeeper
 
Join Date: Mar 2012
Posts: 18
no i haven't gotten the comression checked yet.. illl post the results as soon as i get it and also im gonna try it withouut the cat.. as soon as i do it .. the results will be posted.
deepak is offline   Quote Quick Reply
Old 03-19-2012, 02:35 PM   #12
Jeeper
 
gmcnutt13's Avatar
 
Join Date: Feb 2012
Location: Fontana, CA
Posts: 43
Id almost bet you just need to re-gear it. I have a 4.2 5 speed on 32" tires. And i cant even use 5th gear unless i am going down hill. And 4th is at about 2,200 RPM's at 55 or 60 MPH. And going up a steep hill in 4th is almost worthless unless i get a good run at it. lol. Unless i have a clogged cat or something also.
gmcnutt13 is offline   Quote Quick Reply
Old 03-19-2012, 02:43 PM   #13
Jeeper
 
gmcnutt13's Avatar
 
Join Date: Feb 2012
Location: Fontana, CA
Posts: 43
Oh and i have the stock 3:07 Gear ratio
gmcnutt13 is offline   Quote Quick Reply
Old 03-20-2012, 01:09 PM   #14
Jeeper
 
Join Date: Mar 2012
Posts: 18
The compression test passed..so I need to re gear it and time for new cat
deepak is offline   Quote Quick Reply
Old 03-21-2012, 01:20 AM   #15
Jeeper
 
4bratsdad's Avatar
 
Join Date: Jan 2012
Location: Springfield,IL
Posts: 50
Images: 11
Angry

mine was doing the same thing i have a 2.5 w 32'' tires, i have got it up to 65-70 a couple times on not so windy days downhill but have never been able to use 5th gear,found out my cat had been gutted so i did new cat back yesterday, it ran better , more power, and then clutch went out today and it wasnt even slipping
4bratsdad is offline   Quote Quick Reply
Old 03-21-2012, 11:39 AM   #16
Jeeper
 
gmcnutt13's Avatar
 
Join Date: Feb 2012
Location: Fontana, CA
Posts: 43
Your cat being gutted actually caused a loss in power? I know engines need back pressure to run properly but i would figure that the muffler would be plenty. I need to check mine out.
gmcnutt13 is offline   Quote Quick Reply
Old 03-21-2012, 04:19 PM   #17
Jeeper
 
Join Date: Mar 2012
Posts: 18
im just gonna take out cat and check what happens..
deepak is offline   Quote Quick Reply
Old 03-22-2012, 12:49 AM   #18
Jeeper
 
Join Date: Feb 2012
Posts: 56
just start it and fill the exhaust coming out of the tail pipe if it fills like a soft breath it is clogged if you can fill it sputter it probably ok.
2fastc is offline   Quote Quick Reply
Old 03-22-2012, 12:24 PM   #19
J20
Jeeper
 
Join Date: Sep 2011
Location: Johnstown Ohio
Posts: 31
Has your 92 always done this or did it just gradually start losing power?
J20 is offline   Quote Quick Reply
Old 03-22-2012, 09:10 PM   #20
Jeeper
 
4bratsdad's Avatar
 
Join Date: Jan 2012
Location: Springfield,IL
Posts: 50
Images: 11
if im right the o2 sensor measures the exhaust flow and if the converter isnt there to slow it down a bit , it tells the computer to give your engine more fuel to compensate ,causing it to run richer -using more fuel, mine seemed like it had more pep after i installed the new cat muffler and tailpipe, i havnt really been able to check mileage yet cant replace my clutch till wed, my buddy had a f-150 v8 could spin rear tires on dry pavement took his out and couldnt spin them anymore and used extra 30 bucks a week in gas, put it back on thing went back to norm, i think removing the cat only helps on pre computer vehicles, my opinion

4bratsdad is offline   Quote Quick Reply
Reply

Tags
catalytic , engine , gas , wrangler

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
2012 JKU Rubi Check Engine Light - Misfire Cylinder 6 dbullion JK General Discussion Forum 153 10-22-2014 04:24 PM
Cold Start Engine Noise JeepOnTheRock JK General Discussion Forum 9 10-06-2012 08:45 AM
Replacement Engine - Informal Poll / Suggestions CrimsnTide TJ General Discussion Forum 5 03-19-2012 02:05 AM
1995 Wrangler YJ 4.0i - which engine oil? jonnyboyo YJ Tech Forum 5 03-17-2012 11:03 PM
engine ticking/knocking sound goodwrench67 TJ General Discussion Forum 18 03-17-2012 08:19 PM



Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 06:36 PM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC