Infamous stalling problem identified, temporary cure 1997 grand Cherokee - Page 51 - JeepForum.com

 1Likes
Reply
 
LinkBack Thread Tools
post #751 of 888 Old 05-04-2012, 10:46 AM
rhurd
Registered User
 
Join Date: Jan 2012
Location: Kansas City
Posts: 3
Sick Truck

Hello! I have a 97 jeep cherokee and I have replaced ignition coil, throttle sensor, crank sensor, fuel pump distributor cap, map sensor, had a tuneup and my car still backfires like I'm shooting at someone it just shuts down and sometimes its starts right back up sometimes it takes a while. This happens at anytime of the day and it dosen't matter weather it is cold or hot. Idles real bad and no codes comes on any more other than 11 which is new. The check engine light dose not come on just dies. I love my jeep and now everything under the hood is almost new including the starter, battery, belts and wires. HELP!

rhurd is offline  
Sponsored Links
Advertisement
 
post #752 of 888 Old 05-04-2012, 12:45 PM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,949
Quote:
Originally Posted by rhurd View Post
Hello! I have a 97 jeep cherokee and I have replaced ignition coil, throttle sensor, crank sensor, fuel pump distributor cap, map sensor, had a tuneup and my car still backfires like I'm shooting at someone it just shuts down and sometimes its starts right back up sometimes it takes a while. This happens at anytime of the day and it dosen't matter weather it is cold or hot. Idles real bad and no codes comes on any more other than 11 which is new. The check engine light dose not come on just dies. I love my jeep and now everything under the hood is almost new including the starter, battery, belts and wires. HELP!
I'm guessing it's a 4.0. Grand Cherokee?
If so, have you checked out PCM connections?


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ZeeJay1997 is offline  
post #753 of 888 Old 08-24-2012, 05:17 AM
Jeepman69
Registered User
 
Join Date: Apr 2008
Location: somewhere
Posts: 1
Hey guys, longtime lurker, but new poster.

I have a 96 ZJ with a 4.0 engine.

Won't go into massive detail here, but over the past 4 years I have (like everyone else) sunk a lot of time and money into this *&%%$*$^%(%$(%
thing. Love the vehicle, but Chrysler can kiss my ***.

Am now on PCM #3.

Went through all the rubbish replacing sensors, etc. due to random stalling, hard starting, etc.

Finally bought a reman PCM (dunno if it was just flashed or if it was actually rebuilt) from a company called (I think) All Computer Resources or something like that in Florida.

Thing ran like a champ for about a year. Then the symptoms began again.
PCM had a lifetime warranty, so I got a replacement last September.

Ran a little better, but still acting fritzy on occasion.

Then got worse and worse and worse.

Found out it was running really rich, and it had destroyed my Cat.

Did not think the PCM had gone bad, so I replaced my Cat.

Still random dying, so I took it to a different mechanic than the one I had for years. They did a resistance measurement on the PCM. I did not ask what exactly on....I was told if the resistance was less than 5 ohms, the PCM was bad. And they said it WAS bad.

So I bought a reman PCM from AutoZone after reading through many threads here. Ran like a champ!

Then I began to notice going up slight inclines, it would lose power.
Then it got to the point that I could not even go over 50 mph on flat level highway.
So I went back to the new mechanic, only to find that by replacing the cat before I replaced my PCM, the PCM was causing the engine to run rich (still) and it ruined the cat. And....it had clogged my muffler.

SO.....replaced the exhaust system (Cat + muffler + downstream 02 sensor), and now is running great.

Ran an OBD II scan on it yesterday for the hell of it. Came up with a P0351 code....the damnable ignition coil circuit.

Not asking for info on that code....I have been reading up on it, and even though I am getting the code, the engine is running great with no problems.

The only reason I popped in here to post, was just to say you guys have provided all of us Jeep owners with a massive amount of info, and I just want to say thanks.

My ZJ is my only vehicle at present, and being unemployed, I have no idea when I will be able to buy another vehicle, but as much as I hate to say it, first chance I get, I am going to sell the ZJ.

Really irritates me that Chrysler made such a poorly designed vehicle and foisted it off on so many unsuspecting people.

Sure, the entire vehicle is not poorly designed, but the PCM surely was, and even though my vehicle is running great at present, I can never rest easy, as I know just a sure as I am typing this that eventually the PCM or one of the sensors will go out again with in the next year or so......

These vehicles are supposed to be the most rugged and durable vehicles.....

But the mid-90s Cherokee series cannot be counted on due to the crummy design of the electronic ignition and engine system that runs off the PCM.

Hell, I learned to drive when I was 13-14.......on a 1942 Willy's MB and a 1943 Ford....both army jeeps!

Those were rugged, easy to fix, reliable, etc.

I went on to drive deuce and a halfs in the army out of Ft. Lewis, WA in the late 70s, and those also were dependable.....

Just bothers me that the Jeep name does not really mean nearly as much as it used to in terms of reliability.

Hell, if Jeeps were built in Japan, you could depend on them....

But oh well.

Anyway, as long as I have this ZJ, I am sure I will be coming here to find answers to my questions.

Thanks guys for all your help.

Jeepman69 is offline  
 
post #754 of 888 Old 08-24-2012, 01:52 PM
Oldfrog
Registered User
2007 WK 
 
Join Date: Feb 2008
Location: Louisiana/Texas
Posts: 5,092
The 96-98 PCMs are famous for going out. Especially the so-called "re-man" ones out of the 2 Florida companies. It's my opinion that they suck. Both of them.

There is a write up on this forum about fixing them yourself if you are handy with a soldering iron.

Other than that, so far, my 2nd PCM which was the Cardone brand is doing well. ( bought it from O'reilly's)
I now carry a spare.

When the PCM goes.....it throw all kinds of codes. None of which are reliable, due to the making and breaking of contact on some of the connector pins' soldered joints. Just make sure you dont have some shorted wiring leading from a sensor, which might cause a PCM to fry....such as the downstream O2 sensor at the cat. The wiring harness leading to it tends to get farckled up at times. But that one usually blows the ASD fuse when it shorts.

BTW, Thanks for your service.

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
Oldfrog is offline  
post #755 of 888 Old 09-17-2012, 09:44 PM
islander2u
Registered User
1997 ZJ 
 
Join Date: Jul 2012
Location: Douglasville
Posts: 3
Help, pleaase! 97 JGC, 4.0L auto 4x4 175k miles, well maintained. Prior stalling issue at any speed or idle. Now have 3 new problems after ECM repalcement tonight with reman programmed Cardone unit: check engine light on, continuous fluctuating oil pressure from 0-45 psi (at same speed or rpm), and starts off in 2nd gear, not 1st. Fluid levels are fine. Did not have these problems before changing ECM tonight. I have previously replaced everything imaginable: plugs, wires, cap, rotor, coil, cam position sensor, crankshaft position sensor, air idle control valve, fuel pump/regulator/sending unit/strainer/filter, relays, and have cleaned all relay contacts and added dielectric grease to them & 3-32 pin connecots at ECM, and added the big zip tie. Since none of these replacements changed the stalling problem I installed new ECM. Driving a few blocks it didn't stall but has the tranasmission and oil pressure issues, and check engine light on. Any thoughts?

2islands@bellsouth.net
islander2u is offline  
post #756 of 888 Old 09-17-2012, 10:25 PM
stojakovic
Registered User
1998 ZJ 
 
Join Date: Sep 2012
Location: Richardson
Posts: 24
Quote:
Originally Posted by islander2u View Post
Help, pleaase! 97 JGC, 4.0L auto 4x4 175k miles, well maintained. Prior stalling issue at any speed or idle. Now have 3 new problems after ECM repalcement tonight with reman programmed Cardone unit: check engine light on, continuous fluctuating oil pressure from 0-45 psi (at same speed or rpm), and starts off in 2nd gear, not 1st. Fluid levels are fine. Did not have these problems before changing ECM tonight. I have previously replaced everything imaginable: plugs, wires, cap, rotor, coil, cam position sensor, crankshaft position sensor, air idle control valve, fuel pump/regulator/sending unit/strainer/filter, relays, and have cleaned all relay contacts and added dielectric grease to them & 3-32 pin connecots at ECM, and added the big zip tie. Since none of these replacements changed the stalling problem I installed new ECM. Driving a few blocks it didn't stall but has the tranasmission and oil pressure issues, and check engine light on. Any thoughts?

2islands@bellsouth.net
Have you got it programmed with your VIN?
stojakovic is offline  
post #757 of 888 Old 09-18-2012, 10:48 AM
JS97ZJ
Registered User
2004 WJ 
 
Join Date: Dec 2009
Location: Dingmans Ferry
Posts: 2,286
It looks like the replacement is worse than what you had.
If you put back the original one back in, does the oil, trans problem go away?
Have you zip tied the original PCM very tightly?
JS97ZJ is offline  
post #758 of 888 Old 09-18-2012, 07:01 PM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,949
Quote:
Originally Posted by stojakovic View Post
Have you got it programmed with your VIN?
Does not require VIN programming until 99


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ZeeJay1997 is offline  
post #759 of 888 Old 10-20-2012, 09:37 PM
bigal1962
Registered User
1995 ZJ 
 
Join Date: Jul 2012
Location: Little Rock
Posts: 62
Problem with PCM

YHave a link to a video for you to see what this crazy thing is doing! http://db.tt/KA7YS5F1 it's a big file so may be a bit to load. This thing might run 2 weeks no problems or 2 minutes you never know please help! I've changed out the camshaft position sensor, crankshaft pos sensor, distributor, and fuel pump! Will have to click download to view it but it doesn't really download it just plays it thanks!
bigal1962 is offline  
post #760 of 888 Old 10-20-2012, 09:55 PM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,949
Quote:
Originally Posted by bigal1962 View Post
YHave a link to a video for you to see what this crazy thing is doing! http://db.tt/KA7YS5F1 it's a big file so may be a bit to load. This thing might run 2 weeks no problems or 2 minutes you never know please help! I've changed out the camshaft position sensor, crankshaft pos sensor, distributor, and fuel pump! Will have to click download to view it but it doesn't really download it just plays it thanks!
You said it's fixed in three other posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ZeeJay1997 is offline  
post #761 of 888 Old 10-21-2012, 06:56 AM
bigal1962
Registered User
1995 ZJ 
 
Join Date: Jul 2012
Location: Little Rock
Posts: 62
It is fixed and here was the solution,I posted late and went to bed!

OK 4 days and the car hasn't died, best its run in 7 months. Before that it sat in the best autoshop in the area for a month and they couldn't chase down the issue. After much help from my fellow jeep forum mates that gave me great ideas as to what it wasn't as well as possibly was this is what I did to hopefully fix it was......................
Bad female plug on PCM! Traced the signal to the coil put out from the PCM. This after months of tracing wiring from sensors and plug inputs and outputs and checking signals from crankshaft, camshaft sensors, full pump pressure readings and spark checking measures. I finally decided to just resolder all pin connections but did it one at a time (yes this took several months) and when I got to the one to the coil suddenly the car started and has run fine ever since. Now that I've said watch it die tomorrow! I don't think it will though cause of how well it's ran the last 4 days anyways thanks to everyone for your help! Pin 19 is the output to the coil I have posted a PDF of the layout for this connector in the zj forum

I was asked to post this on here as this thread pertains to this issue, thanks everyone!
bigal1962 is offline  
post #762 of 888 Old 10-21-2012, 07:10 AM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,949
Thanks for clearing that up. So basically the problem was a bad socket in the connector? And you soldered the connector to the ECM?


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ZeeJay1997 is offline  
post #763 of 888 Old 10-21-2012, 08:10 AM
bigal1962
Registered User
1995 ZJ 
 
Join Date: Jul 2012
Location: Little Rock
Posts: 62
Quote:
Originally Posted by ZeeJay1997
Thanks for clearing that up. So basically the problem was a bad socket in the connector? And you soldered the connector to the ECM?
I soldered the wire to the female connector. I can still unplug the ECM like you normally would. I also coated solder with a anti corrosion electrical grease
bigal1962 is offline  
post #764 of 888 Old 12-16-2012, 03:13 PM
henrygeorge
Registered User
1999 WJ 
 
Join Date: Nov 2011
Location: marietta
Posts: 79
After 2 PCM replacements and zip tie method, I finally went with the hose clamp solution. The zip tie method lasts at most 2 weeks when the dielectric grease starts to break down.

I cut a piece of hard foam to help curve and distribute the pressure across the clamps and reduce vibration under the hose clamp.

I also replaced the short ground cable of the battery, used a brass side post ground connector, and recut the other ground cable and cleaned the corrosion where I stripped the wire. I cleaned other ground connectors but still need to check the ground connector at the fuel pump above the fuel tank. I need to remove the fuel tank anyway to fix a seal where the gas leaks out if it is over-filled.

I added ferrite chokes to the three wire bundles going into the PCM and added a ferrite choke to wires going to distributor. I also made sure all my spark plug wires were crossing to reduce EMI under the hood. The three ferrite chokes recommended from Radio Shack are actually intended to wrap a wire around rather than run a bundle of wires through them. However, I assume something is better than nothing. The wire bundles are running in parallel with minimum twisting. I'm considering grabbing a braided ground cable off a newer grand cherokee in the junkyard to reduce EMI. The hose clamp might even be helping with EMI.

The PCM does seem to be grounded to the firewall with the three screws. The two screws on the front are also not causing any problems and backing them out are likely to increase problems.

I had resoldered the first connector with a junkyard connector. I tried to repin the second connector (white middle one) with a junkyard connector. After repinning, the second connector is more sensitive because a couple of the plastic tabs broke. I plan to resolder the wires of the middle connector with another white connector I obtained from the junkyard once I have more time and less stress. However, I'm going to see how the hose clamp and attempt to control EMI under the hood works out. The hose clamp with the hard foam does seem to be working for now and holding it much more stable than the zip ties. However, I'll need to wait for the dielectric grease to break down to be sure.

It would be nice if there was a kit available which sold a new plastic connector and the pins to repin the connector. I can't believe the computer connection is dependent upon the force of little plastic tabs inside the connector, plastic which breaks down and becomes more fragile with time. The whole design is not acceptable for the operating conditions.

Problems seem to largely be temporarily fixed when dielectric grease is applied. However, they will return if the grease breaks down, especially with temperature changes and vibration.
henrygeorge is offline  
post #765 of 888 Old 12-16-2012, 05:10 PM
ZeeJay1997
Registered User
1997 ZJ 
 
Join Date: Dec 2008
Posts: 8,949
Where did you get your PCMs?

What is the history behind the Jeep? Do you have reason to believe the pins are spread?

If any of the three screws holding the PCM to the bracket are touching the firewall, they are too long. Change them out with 3/16 X 16 X 2" screws. The case of the PCM should be isolated from the chassis with nylon inserts in the bracket.

The dielectric grease should not make any difference in the connectivity of the circuits. It just keeps stuff out.

The locking tabs do not affect the connectivity either. They simply hold the halves together. I've been running mine about a year without locking tabs on the middle connector and no zip ties. It holds itself in, but it is only ran on highway.

If changing the connectors out fixes your vehicle, it will be a rare occurrence.

Is the wiggle test failing? If so, the PCM is most likely bad.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ZeeJay1997 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com 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 e-mail address for yourself.



Email Address:
OR

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
2000 Grand Cherokee Stalling problem garyo WJ Grand Cherokee Forum 6 04-17-2016 02:40 PM
99 Grand Cherokee Stalling Problem pigoo ZJ Grand Cherokee Forum 16 07-09-2015 11:16 AM
95 Grand Cherokee Stalling Problem hondajeep ZJ Grand Cherokee Forum 10 04-16-2012 12:13 PM
1997 grand cherokee computer problem. SSLaser ZJ Grand Cherokee Forum 7 04-11-2010 07:36 PM
1997 Grand Cherokee air conditioning problem bootown ZJ Grand Cherokee Forum 2 08-08-2002 07:13 AM

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 On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome