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


ezeman
July 20th, 2005, 09:32
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

langer1
July 20th, 2005, 09:50
Have you cleaned and tightened your ground connections?

LostintheWoods
July 20th, 2005, 09:58
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.

ezeman
July 20th, 2005, 10:25
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

ezeman
July 20th, 2005, 10:34
I also had charging system and battery checked this am, as well as OBD scan, the scan said MAP sensor voltage to HIGH

thx

badge714
July 20th, 2005, 14:57
The little rubber elbow that connects the map sensor to manifold had a small split in it really hard to see. Just a thought badge714

LostintheWoods
July 20th, 2005, 16:08
If your cps is from the dealer its likely good(i'd check it because im paranoid like that) was the cps harness in good shape?

ezeman
July 20th, 2005, 16:19
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

badge714
July 20th, 2005, 16:25
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/15/24/06/0900823d80152406.jsp Check thru this may be of help to you badge714

ezeman
July 21st, 2005, 05:41
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

Runnin'OnEmpty
July 21st, 2005, 07:04
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.......?

ezeman
July 21st, 2005, 07:31
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

langer1
July 21st, 2005, 08:15
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
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.

ezeman
July 21st, 2005, 16:22
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

ezeman
July 28th, 2005, 06:53
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..

Runnin'OnEmpty
July 28th, 2005, 07:32
I also checked continuity from the MAP plug back to the wires just before they go into the connector into the PCM. 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........

ezeman
July 28th, 2005, 07:38
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

ezeman
November 4th, 2005, 09:16
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

langer1
November 4th, 2005, 10:11
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
12in is way low, it should be 20in

Runnin'OnEmpty
November 4th, 2005, 12:21
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.

ezeman
November 7th, 2005, 12:13
ok so I did another vac test, its now 8 in hg, so I think i definately got a vac prob. Now I keep the gage on, and pull and plug various vac tubes off the intake manifold with no change in vac pressure, does this mean intake gasket or something? Any other ideas on where to look? I thought I read something on the use of propane to trace this down..any ideas?

and low vac leads to the high MAP voltage, and likely my 3100 RPM rev limit, as the engine is likely straving as its too lean.

I can still limb/drive it around, but it stalls at stops (unless i give it some gas) and still chops out at 3000 RPM, right after the shift point!! woohoo

thanks again for your vac leak tracking help!

eze

langer1
November 7th, 2005, 14:40
ok so I did another vac test, its now 8 in hg, so I think i definately got a vac prob. Now I keep the gage on, and pull and plug various vac tubes off the intake manifold with no change in vac pressure, does this mean intake gasket or something? Any other ideas on where to look? I thought I read something on the use of propane to trace this down..any ideas?

and low vac leads to the high MAP voltage, and likely my 3100 RPM rev limit, as the engine is likely straving as its too lean.

I can still limb/drive it around, but it stalls at stops (unless i give it some gas) and still chops out at 3000 RPM, right after the shift point!! woohoo

thanks again for your vac leak tracking help!

eze
You need to cap all the lines off to find the one that leaking, don't forget your Vacuum brake booster

ezeman
November 7th, 2005, 16:24
hey thanks for the advice, I took each vac 'takeoff' line off and plugged it with my finger, one at a time. There was no change in vac pressure as I removed and plugged each one. So i am wondering if I still need to plug them all at once and take a reading? I though maybe the manifold was leaking cause i got no change by individually plugging each vac lead off the manifold..make sense?

thanks again

Runnin'OnEmpty
November 7th, 2005, 18:16
As Mr Langer1 says, don't forget the brake booster.

MoFo
November 7th, 2005, 19:36
The brake booster would be my most likely suspect too.

If you pull that hose and plug the fitting to the engine and still have the problem, I would suspect valves before a leaking manifold.

The propane test is dangerous and I don't recommend it. You have to take an unlit propane torch, turned on low, and hold the end very close to spots you suspect a leak. When it finds a leak, the propane is sucked into the intake and the engine RPMs will increase briefly, while the PCM closes the IAC valve. The engine will die when the torch is removed. This has to be done on a running engine and is a fire risk.

The best way to check for leaking valves is with a bleed-down test. You crank the engine untill the piston is at TDC and pump air into the cylinder, through a set of guages. Adjust your compressor so the first guage reads 100 PSI. There is a small orafice in the block between the guages. Air flows throght that orafice, past the second guage, then into the cylinder. If the second guage reads 88 PSI, you have a 12% leakdown. With a stuck or bent valve, I would expect an 80% or better leakdown (20 PSI on guage 2). I bought my bleed-down guage set at Summit for $75 about 5 years ago.

This check needs to be made on all the other cylinders too. You need to hand-crank the engine 1/3 of a turn, then move the test guages to the next cylinder in the fireing order.

ezeman
November 9th, 2005, 19:52
ok , I did the whole vac test, by plugging each one. I think its strange that it could be a valve or cylinder problem when the thing runs great between 1000 and 3000 RPM. I can also only drive it with the MAP disconnected, otherwise with the MAP connected it stalls alot and cuts in and out at random. The brake booster vac line has no effect on the vac guage when i disconnect and reconnect, i still get about 7 in Hg on the gage, ditto with connecting or disconnecting any other vac line off the manifold.

I also did a the 'spray liberally with brake cleaner" test as opposed ot the propane, and reall couldnt find any changes int he engine running when I sprayed nearly everything intake and vac related

So a bleeddown test is next on the list? Sounds involved but I hace already been so far, and got taken for 379$ at the mechanic already...gggrrrrr

thanks for sticking with me peeps

eze

Runnin'OnEmpty
November 10th, 2005, 10:12
Ezeman, there's one other thing that will cause low manifold vacuum and the other symptoms, and I don't know why I didn't think of it sooner:

CLOGGED CATALYTIC CONVERTER

If yours is like my 96, you can loosen the clamp that holds the cat on, and slide it back to open the exhaust up. Then test the manifold vacuum with the engine idleing. If the vacuum increases, then you need a new cat.....

Here's hoping that's it,
ROE

ezeman
November 10th, 2005, 10:18
ROE

Thanks for that suggestion. I changed the CAT about a year and half ago to a high flow cat, along wiht a new muffler. I will beat on the CAT to see if I hear anything chunky, but because the Jeep runs great other than this bad idle, limited RPM to 3000, and stalling stop signs, aka the bad idle, I think i can rule it out.

I am just stumped as to why last week i measured 11 in and this week its 8 in of Hg..

I am goin to retighten the manifold bolts again here this am, and think about the bleed down test or pulling the valve cover to see if i got bad valve, but again cause it runs so good otherwise....

thanks!

stumped .....eze

langer1
November 10th, 2005, 10:28
I am just stumped as to why last week i measured 11 in and this week its 8 in of Hg..
If the 8 was taken cold and the 11 with a warm engine that would explain it.

MoFo
November 10th, 2005, 18:42
EZE,

I wish I lived closer, I would bring you my bleed-down guages.

ROE had a good idea with the cat. Too bad it is so new, that kinda rules it out. How well do you trust the vacuum guage you have? Do you have a friend close with another you can check it against?

A vacuum leak is most evident at idle and should not affect high RPM operation. A valve problem, on the other hand, will be bad at idle and get worse at high RPM. You may not see a valve problem from the top. You would see a stuck valve, or a bent valve. You would see a collapsed lifter, but you would not see a burnt valve or a burnt seat.

A compression test guage is much cheaper than a bleed-down guage set. It is not as definative, but would pick up most valve problems.

Good luck and please let us know what you find.

ezeman
November 10th, 2005, 21:11
I guess I trust the guages as far as I can throw them, got them at Advance Auto for about 30-40$ bucks. I tightened the manifold bolts earlier today, none were real loose. I got a shitty, but not as shitty as usual idle after I cleaned the IAC and TB. I also reset the computer, and hooke dhte MAP back in to see what was going on again. I still got the low 7 in HG vac on the gage. The engine revved fine up to 5k RPM, but ran real bad cutting out at random again all through a low RPM range (1000-2500) while under load, and would go no faster under load. The exhaust seems plenty strong out the muffler to rule out the cat. Goin nuts here :S

I will try comp test perhaps tommorrow.

thanks again!!

eze