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Unread 05-15-2013, 10:19 PM   #1
97cherokeeman
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1997 XJ Cherokee 
 
Join Date: May 2013
Location: East Wenatchee, Washington
Posts: 5
Bad idle, bad throttle response, and delayed deceleration.

Hey guys. I've been lurking this site for a while now and the amount of info you guys have is insane! It's helped me out a bunch with my 97 cherokee (4.0L 286,300 miles) up until now. I started having problems a couple months ago. Started losing a bit of power up hills, and it would stagger and occasionally back fire when first started. So I started trouble shooting.

I started with the basics, fresh plugs. Wires. Air filter. No fix.

Checked out the distributor rotor and cap and actually found a hole in the case of the distributor. So I replaced all of it. No fix.

So I tthought I would check the timing chain. Buddy of mine suggested it may have skipped a tooth. Got a fresh chain, timed just right. No fix.

So I turned to the throttle body. Cleaned it and the sensors out. IAC was filthy. Put it all back together. No fix.

During all of this I found a crack in the exhaust manifold. So I ordered an APN header to replace it. While I had everything apart I replaced the bad motor mount (probably the cause of the cracked exaust) and cleaned the injectors. Got it all back together and still. No fix.

So I took an OBD ll reader to it and it threw an a## load of codes at me. From the IAC to the TPS to the Map to the O2 to a couple others that I can't remember. Got about 12 pages printed out from Oriellys of what the codes were. So I tested and replaced the TPS and MAP and Cps sensors. Still, no fix!

I've checked for leaks in the vacuum system (although I'm sure my methods weren't the best) and can't seem to find anything. I'm just at a loss!

When I start it up it idles rough and seems to run rich. When I hit the gas it falls flat before slowly catching up to itself and levels out about 2000 rpm's. Then when I let off the gas it has a slow return back to idle.

So to whoever took the time to read all of this thank you! Any help is greatly appreciated!


Last edited by 97cherokeeman; 05-16-2013 at 10:55 AM..
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Unread 05-15-2013, 11:57 PM   #2
billb2011
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1999 XJ Cherokee 
 
Join Date: Jul 2011
Location: Minford, OH
Posts: 172
I had a similar problem a while back and found out I had a blown fuse that was related to the O2 sensors, It is called the "O2 sensor heater" fuse and is located in the power distribution block in the engine compartment it is a 15amp and is in the row closest to the firewall second row from the passenger side. Wont hurt to check it out since its an easy fix if that's the problem. Maybe the actual sensors are bad if the fuse isn't blown. Good luck with it.
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Unread 05-16-2013, 10:46 AM   #3
97cherokeeman
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1997 XJ Cherokee 
 
Join Date: May 2013
Location: East Wenatchee, Washington
Posts: 5
Thanks for the response. I just went through all the fuses and they are all fine. And I've got a brand new O2 sensor in it. So I'm still at a loss.

Last edited by 97cherokeeman; 05-16-2013 at 11:02 AM..
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Unread 05-16-2013, 10:46 AM   #4
carolinacheroke
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2001 XJ Cherokee 
 
Join Date: May 2013
Location: Roxboro, NC
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Have you checked the catalytic converter? Not on my jeep but on a chevrolet in the household, had very similar problems and I tried many frustrating things before the cc. A new converter fixed it all.
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Unread 05-16-2013, 12:55 PM   #5
97cherokeeman
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1997 XJ Cherokee 
 
Join Date: May 2013
Location: East Wenatchee, Washington
Posts: 5
Strait piped to a flowmaster. So no cat on mine :/
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Unread 05-16-2013, 05:00 PM   #6
97cherokeeman
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1997 XJ Cherokee 
 
Join Date: May 2013
Location: East Wenatchee, Washington
Posts: 5
Update: just scanned it again with an OBD ll reader and came up with four codes...

P0118 : Temp sensor (Temp gauge in dash works fine)
P0108 : Map sensor (which is new)
P1391 : Intermittent loss of CMP or CKP
P0500 : Vehicle speed sensor malfunction. (I don't know if related but my speedo works just fine)
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Unread 05-17-2013, 06:28 PM   #7
tjwalker
It's the crank sensor!
 
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1999 XJ Cherokee 
 
Join Date: Nov 2007
Location: Central Minnesota, MN
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Test and or replace the coolant temp sensor. It's located on the thermostat housing for your 97.

If that sensor is fubar, it will give incorrect data to the computer, which will then try to change the fuel/air ratio to compensate for it. You CAN have correct temp readings on the dash gauge and incorrect readings going to the computer.
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Unread 05-28-2013, 12:55 PM   #8
97cherokeeman
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1997 XJ Cherokee 
 
Join Date: May 2013
Location: East Wenatchee, Washington
Posts: 5
Went through the engine with my uncle the other day and he seems to think that the valves in cylinders 3 and 4 are shot. Would pull the plug wires off while jeep was running and those two were the only ones that wouldn't effect the idle. I know I have spark to both cylinders and the injectors are fine. So that's just the next option.
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Unread 06-01-2014, 11:23 PM   #9
Kanada06
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1998 TJ Wrangler 
 
Join Date: Jun 2014
Location: St. Cloud, Mn
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I am having a similar problem in my jeep, was it the valves in your jeep? Thanks
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Unread 06-02-2014, 06:41 PM   #10
BlueRidgeMark
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1994 XJ Cherokee 
 
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Location: SomewherealongtheBlueRidge, VA
Posts: 601
Quote:
Originally Posted by tjwalker View Post
Test and or replace the coolant temp sensor. It's located on the thermostat housing for your 97.

If that sensor is fubar, it will give incorrect data to the computer, which will then try to change the fuel/air ratio to compensate for it. You CAN have correct temp readings on the dash gauge and incorrect readings going to the computer.
TJ, I'll check that on mine, too. I'm having a similar gremlin.

Mine is throwing a 1694 code, and a TPS code. Bad news - the TPS is a brand new one from the dealer.

What's the test for the coolant temp sensor?
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Unread 06-02-2014, 09:26 PM   #11
Jeep93cherokee
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1993 XJ Cherokee 
 
Join Date: Jun 2014
Location: Sykesville, Maryland
Posts: 2
I'm having a similar problem starts up fine idles good but as soon as you push the gas it sounds like its misfiring like crazy an backfires so I replaced the cap rotor wires an still nothing took it to a buddy of mine an he looked at it for 3 days then called me an said he had the solution it was the crank shaft as soon as he unplugged it it ran perfect so he ordered one an we put it in made sure it went in an it was on time by marking the block plugged it in an ran fine for 5 min an bam! Problem came back he said it had to be the computer so I got it ( don't know if it needs to be flashed ) put it in an ran fine then started throwing a fit again I'm so confused on this thing I've replaced everything that would cause this that I've looked up on here an people having similar problems kinda but seems like no one has please help it's my only vehicle an idk what to do
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