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Feb 20, 2010 | 08:50 AM

#16

96Cherokee113

CF Veteran

Joined: Nov 2009

Posts: 1,261

Likes: 0

From: New Jersey

Year: 1996

Model: Cherokee

Engine: 4.0 HO

Quote:

Originally Posted by FrankZ

Wait, wait, wait!!!
Off by a little? Even off by 1 tooth is enough to cause major performance problems and most certainly throw a P1391 Error Code. Many people often misdiagnose this as a faulty Crank or Cam Position Sensor. So the question you need to ask is this, Since the distributor is not adjustable, how did they correct the problem?

The PCM in our OBD2 equipped XJ's controls the distributor timing. If the distributor is not properly installed (yes, even by 1 tooth) the PCM will report a problem via the CEL. The Crank and Cam position sensor signals will not be sync'd if the distributor is improperly installed.

So as a result of improper installation you can expect your cat to be washed with unburnt fuel, O2 sensors to report incorrect O2 content in the exhaust which leads to more problems as the PCM tries to compensate.

There really isn't any way to be "Off by just a little". It has to be exact.

I agree 100 percent. We have an explanation and Frankz provided all the evidence to go with it. I say pull that distributor, remember how it was placed in there, and keep rotating it one tooth at a time until it runs right...And don't bring it back to that shop.

Feb 20, 2010 | 10:01 AM

#17

captainwoot

CF Veteran

Joined: Aug 2009

Posts: 1,047

Likes: 3

From: Hanover,Ont, Canada

Year: 1991

Model: Cherokee

Engine: 4.o

x2... Frankz is right on the money....

Feb 20, 2010 | 10:25 AM

#18

Hommersimpson

CF Veteran

Joined: Jan 2010

Posts: 1,087

Likes: 1

From: St Augustine Florida

Year: 1992

Model: Cherokee

Engine: 4.0

Well normally at cat will cause problems only after a few minuts of running not when its first cranked up.. takes time to start building up back pressure..Now if it runs good for the first few minuts then starts to act up.. then look into the cat...if its rattlying then it def can be pluging up..
Hope you get it fixed...

Feb 20, 2010 | 01:02 PM

#19

jusper88

Thread Starter

Senior Member

Joined: Feb 2009

Posts: 850

Likes: 0

From: Roswell, NM

Year: 1997

Model: Cherokee

Engine: 4.0 L

Quote:

Originally Posted by Hommersimpson

It is rattling like a (BEEP)! And I can see the muffler where it is rusting through.

Mar 2, 2010 | 08:17 PM

#20

978Jeep

Junior Member

Joined: Jan 2010

Posts: 69

Likes: 0

From: Londonderry, NH

Year: 1997

Model: Cherokee

Engine: 4.0L HO

My cat rattles pretty bad... found a better than oem replacement for <$90 so make sure you shop around for the best price when you go replacing that...

I just replaced my spark plugs and my car was bucking... i checked the gaps and reinstalled and it went away.... noticed the bucking up to 2k rpms as you described but it was much more faint...

so this goes to say that spark plug gaps should always be checked.

Good luck with your 97 sport... i have the same model, 2dr, black 4.0... love this thing almost as much as my M3

Mar 3, 2010 | 07:57 AM

#21

jusper88

Thread Starter

Senior Member

Joined: Feb 2009

Posts: 850

Likes: 0

From: Roswell, NM

Year: 1997

Model: Cherokee

Engine: 4.0 L

Ok so they found out it was CPS and they idiots at first shop hadn't adjusted the dist. just right. (Thanks to FrankZ for the suggestion) Also my CAT was clogged, so I got a new Hi-Flow and Magnaflow Muffler. I'll add pics and maybe a vid to my build thread soon. ADMIN! Please close this thread!