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hi..can u help me, my 96 xj wont run..stalls, goes, acts strange

E

ezeman

NAXJA Forum User
Location
Denver
Hi all, yhanks for reading

I have a 96 xj, 150k 4.0

I have posted about htis problem I have had that is now worsened.

A year ago, I get a code 14 (map sensor) fault, and the motor starts sputtering randomly and randomy it shuts down at 3100 rom, then turns right back on after the rpm's drop to 0 (this happens cyclicaly and quickly)

I tried reset computer, and the code shows up again. I check wiring, replace MAP, check voltages. I get 5v on 1 and 2 pins only, my chiltons says 5v on 1 and 3 pins..so i am thinking ...hmmm

so for the last week, the problem has again gotten worse, now any acceleeration causes the motor to shut down, sometimes permanently, sometimes it will idle or surge up to rpm's again.

I have also replaced TPS, IAC, Crank PS, plugs, wires, fuel filter, all within the last year, trying to solve this. I also checked continuity from the MAP plug back to the wires just before they go into the connector into the PCM.

Thanks in advance for any help or suggestions, I really dont want to visit the STEALER/DEALER if I can avoid it.


ezeman
 
You mentioned u have replaced the cps, have you checked that it actually works? About 50% of them are bad right off the shelf from what I understand. I installed one, didn't work, went to the dealer, my wallet got raped but my Jeep works. It might be worth the expense of going to the dealer if only to avoid wasted money in the long run. Plus if they dont fix the problem they will refund your money and try something else.
I had a similer problem and would bet its ths cps.
 
Thanks for the feedback guys.


I did clean and sand the ground connections.

I also got the CPS for the Stealer, 104$ I think (ouch) Are you suggesting I test it or just take it back?

:)

e
 
oh yeah

I also had charging system and battery checked this am, as well as OBD scan, the scan said MAP sensor voltage to HIGH

thx
 
yes, I got the CPS from the dealer. The harness looks ok, and i didnt see the infamous burnt wires. I was also thinking maybe PCM is going bad? or i have an open in a wire? I am so stumped and frustrated. I have it scheduled in a shop for Friday, but I really am trying to avoid that visit.

I cant even drive it now, it dies with any push on the accelerator.

FYI the sypmtoms do go away if I shift it in neutral..

thx
 
thanks guys, I checked the elbow, its good by using my 'blow test' with fingers

I also double checked the resistence for the three leads of the MAP, as well as swapping in the old MAP, all no change.

still on the hunt, I suspect maybe a wire is open from another sensor that shares this circuit with the MAP maybe??

:)

e
 
EZE, if you've replaced the TPS, and exchanged the MAP sensor for a known good one, then I'd suspect a faulty fuel pump. It's possible that the fuel pressure is enough to start and idle, but not enough when the engine is under load.......?
 
I was thinking that, I did a fuel pressure test a few months ago, and it was fine at both idle and reving, but I guess it would be tough to test under load. Any ideas on how I can test that short of having someone ride in the engine compartment while watchin the gage..hehe

I dont hear the squealing or any other fuel pump indicators, but I have heard of many pump problems with the ol' XJ
 
ezeman said:
I was thinking that, I did a fuel pressure test a few months ago, and it was fine at both idle and reving, but I guess it would be tough to test under load. Any ideas on how I can test that short of having someone ride in the engine compartment while watchin the gage..hehe

I dont hear the squealing or any other fuel pump indicators, but I have heard of many pump problems with the ol' XJ
Click to expand...
A pluged fuel filter would pass enough fuel for idle, check the fuel pressure again.
I'm also thinking a bad injector, that could explain the high voltage o2 reading.

Don't forget scanner code's are always just a starting place, they don't mean that the sensor it bad. If your running rich the o2 reading will be off.
 
Last edited:
one other intersting note, if I disconnect the MAP and reset the computer (via battery disconnect) i immediately again get the CODE 14 MAP

I also noticed a clicking sound near the main enginer compartment fuse panel with KEY ON ONLY when I backprobe Nos. 1 and 2, or jiggle random wires..but I really cant seem to locate a specific spot, it really is random, like the clicking sound takes a few seconds to reset itself before I can make it reoccur by this wiggling and probing (that sounds bad..haha).

I am off to check resistence in the harness from injectors and sensors back to the PCM..

I am also on the hunt for a fuel pressure guage, as suggested


thanks alot guys...

I cant wait till I find WTF it is..... I have posts about this from months ago..but the problem used to come and go.. now its permanent
 
379$ dollars later

I had to laugh when the mechanic told me "this problem had got me by the balls"

Well, the problem was a bad wire (green w/red stripe) in the actual connector to the PCM. You would only be able to tell this if you checked continuity between the sensor lead and the INSIDE of the PCM connector, or by probing the pin at the connector as opposed to wire itself on the outside of the connector. FYI this would be the connector to the PCM along the drivers side, behind the fender.

Hope this helps someone in the future..
 
I also checked continuity from the MAP plug back to the wires just before they go into the connector into the PCM.
Click to expand...
Ezeman, was the bad wire connection the one that goes to the MAP sensor? If so, it sounds like you were on the right track, just didn't go far enough....?

That was a toughy........
 
The bad 'spot' was the where the wire terminated at the PCM connector pin itself. This wire was one of the 3 from the MAP that runs back to the PCM. I was on the right track, my mistake was not checking continuity from connector to connector, as I only probed the wire right BEFORE it goes into this big PCM connector..DAMMIT :)

live and learn, this was the first time I ever taken my jeep to a mechanic cuase I couldt fix something

e
 
DAMMIT

Problem is back. I noticed the wires were looking frayed at the MAP sensor connector, so I resoldered those last night. After the resolder job, the original problem I posted is back,. the idle is randomly rough, the 3100 RPM shutdown cycle is also random as to when it occurs, the motor sometimes idles so low it almost or does quit. Sometimes the check engine light comes on sometimes it doesnt. Codes are 11,12,14,55. Sometimes no code 11, only the 14 12 and 55. All these symptoms have been in the last 24 hours btw.

I checked and cleaned grounds last time, replaced with Jeep OEM CPS, now I am getting ready to put a new d/s Bosch o2 sensor in (already replaced u/s a while ago) Vac is measuring 12 in at idle, and drops to between 0 and 5 in on light or heavy accel. Does that sound right?

I am really frustrated and any help is appreciated.

e
 
Last edited:
ezeman said:
DAMMIT

Problem is back. I noticed the wires were looking frayed at the MAP sensor connector, so I resoldered those last night. After the resolder job, the original problem I posted is back,. the idle is randomly rough, the 3100 RPM shutdown cycle is also random as to when it occurs, the motor sometimes idles so low it almost or does quit. Sometimes the check engine light comes on sometimes it doesnt. Codes are 11,12,14,55. Sometimes no code 11, only the 14 12 and 55. All these symptoms have been in the last 24 hours btw.

I checked and cleaned grounds last time, replaced with Jeep OEM CPS, now I am getting ready to put a new d/s Bosch o2 sensor in (already replaced u/s a while ago) Vac is measuring 12 in at idle, and drops to between 0 and 5 in on light or heavy accel. Does that sound right?

I am really frustrated and any help is appreciated.

e
Click to expand...
12in is way low, it should be 20in
 
Ezeman, I thought 96's were OBD II and had alphanumeric codes such as P0155, instead of two digit codes.....?

As Langer says, manifold vacuum at idle should be 18-20 in/Hg, and certainly higher than the 12 you're getting. This sounds like a huge vacuum leak, or a severly retarded timing problem.......?

As for the codes, the 12 and 14 are indeed MAP related. The 11 is no crank reference signal, which I would suspect is no CPS signal. The 55 is an end of test code.
 
Last edited:
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