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Im stuck!

M

MountainGoat

NAXJA Forum User
Location
PNW
Well I got off work early. Driving my 1988 XJ 4.0 AW4 all stock. New cap and rotor, plugs and wires. All is good there. Just replaced the water bottle cause it was leaking. Now thats happy. The engine was getting hot though. It did reach the red one time for a minute or two. Yesterday I pulled off the intake hose and cleaned out the throttle body and intake with some carb cleaner. Started it up and drove around. Last night it was driving fine and today it was starting and driving fine.

Up to the point of my getting home that is. Kids are out of school now so I decided to stop by the bank, get some cash, and take the kids out for some activities. I just leave the bank and decided to turn on the AC.......
I just pulled out of the bank when the engine makes a funny sound and then stahls out. I am unable to get it started. It reminded me of when an engine vapor locks.
So I finally get her started again and she is not very pleased and starts to studder some but Im moving,, for another 60 feet before she dies and allows me to coast into a construction zone. I sit there and she starts and dies right away....... Radiator looks ok, but I leave the hood open for now. Ten minutes go by and I try to start the XJ, it runs and stops, I try again and she runs, I place into drive and it dies, then I try again and she stays running, I drive about 60 feet and she dies, I coast to the end of the road and try again. Will not start at all now. I wait for a few minutes and try, nada.... I then wait for ten minutes just incase its heat related, Nada...... I finally decide to call a truck..... its on the way... jeep starts up.... I get two blocks and call the truck back and cancel.... I can keep her running by placing into neutral and leeping my other foot on the gas.... as long as I keep it to a certain rpm it will continue to run... it still died every other mile.. I make it home and rev the engine a few times and let it idle.... I rev it again and it stahls out... wont start.....




My temp gauge is at 210 so thats ok. My oil pressure is low but that gauge is wacky anyway. The only thing I did today was add some radiator cleaner to the bottle and that was only in for about half an hour. You can drive around for over six hours with that stuff so I dont think its that. Up to the time this happened I noticed no signs that this was going to happen.

Anyway Im stuck at home.... My wife has to work tonight so I might be able to get her car while I try and trouble shot this issue.

I did some searches.... MAP? IAC? Etc.? Or is it something else?
 
MountainGoat said:
Well I got off work early. Driving my 1988 XJ 4.0 AW4 all stock. New cap and rotor, plugs and wires. All is good there. Just replaced the water bottle cause it was leaking. Now thats happy. The engine was getting hot though. It did reach the red one time for a minute or two. Yesterday I pulled off the intake hose and cleaned out the throttle body and intake with some carb cleaner. Started it up and drove around. Last night it was driving fine and today it was starting and driving fine.

Up to the point of my getting home that is. Kids are out of school now so I decided to stop by the bank, get some cash, and take the kids out for some activities. I just leave the bank and decided to turn on the AC.......
I just pulled out of the bank when the engine makes a funny sound and then stahls out. I am unable to get it started. It reminded me of when an engine vapor locks.
So I finally get her started again and she is not very pleased and starts to studder some but Im moving,, for another 60 feet before she dies and allows me to coast into a construction zone. I sit there and she starts and dies right away....... Radiator looks ok, but I leave the hood open for now. Ten minutes go by and I try to start the XJ, it runs and stops, I try again and she runs, I place into drive and it dies, then I try again and she stays running, I drive about 60 feet and she dies, I coast to the end of the road and try again. Will not start at all now. I wait for a few minutes and try, nada.... I then wait for ten minutes just incase its heat related, Nada...... I finally decide to call a truck..... its on the way... jeep starts up.... I get two blocks and call the truck back and cancel.... I can keep her running by placing into neutral and leeping my other foot on the gas.... as long as I keep it to a certain rpm it will continue to run... it still died every other mile.. I make it home and rev the engine a few times and let it idle.... I rev it again and it stahls out... wont start.....




My temp gauge is at 210 so thats ok. My oil pressure is low but that gauge is wacky anyway. The only thing I did today was add some radiator cleaner to the bottle and that was only in for about half an hour. You can drive around for over six hours with that stuff so I dont think its that. Up to the time this happened I noticed no signs that this was going to happen.

Anyway Im stuck at home.... My wife has to work tonight so I might be able to get her car while I try and trouble shot this issue.

I did some searches.... MAP? IAC? Etc.? Or is it something else?
Click to expand...


Not sure about your year FI but you need to be really careful when cleaning the TB with a spray cleaner. Alot are not plastic friendly and can eat a map and tps sensor in short order. The only time I ever spray cleaner in there is with the engine running and my finger on the throttle so I can direct the spray away from the holes in the TB that my 98 has. If you shot the sensor full of cleaner thats prob your problem..
 
If the problem is that it refuses to idle, ie when you let off the gas the RPMs simply go to zero and it stalls then I may have an answer. I had this problem a while back while I was working on a bad NSS. In addition to the above, it also had the quirk that it idled fine when I first started it, it wasn't till I gave it gas that the "Speed" problem occured (you know keep the rpms at a certain level or the bus blows up.) I figured the computer was just confused about me bypassing the switch so I disconnected the battery to reset it. The reset solved the problem for me (that was 18months ago.)

Matt
 
I would start with the fuel filter, it may be clogged. Then move on to the fuel pump. Your problem sounds fuel related. If that doesnt do it change the CPS.
 
Oh yeah, you might also change the auto shut down relay. (ASD)
 
hey guys... thanks for helping out... We had a big storm yesterday and I lost internet access until now...

I drained the radiator last night and replaced the fluids..... I drove it around some and it seems ok for now.... I am still leery about driving around for long periods or far away from home but I will continue to see how she performs....

I cleaned out the throttle body again and ended up scrapping out some crude...

Also one of my main vacuum lines was cracked.... hmm might of been that ehh? I have RTV'd all vacuum fittings until I can get them replaced.

Anyone know where I can buy all the vacuum lines, hoses, ends, etc for an 88 4.0?
 
logdog said:
I would start with the fuel filter, it may be clogged. Then move on to the fuel pump. Your problem sounds fuel related. If that doesnt do it change the CPS.
Click to expand...

I'd say it's almost certainly a bad CPS. You might be able to revive it for a while by disconnecting and reconnecting the sensor to the wiring harness. Clean the connector if it's dirty. You'll eventually need to replace it anyway so do it ASAP.
If that doesn't cure it, disconnect the fuel filter from the fuel pump, put a container underneath the open hose, turn on the ignition, and see if fuel spurts out of the hose. If it only trickles or doesn't come at all, your fuel pump is toast. If the fuel pump relay or ballast resistor were at fault, the fuel pump wouldn't work at all rather than intermittently.
 
Aaaaaaarrrggggggggg!!!!!!!!1

Wle she broke down again. I was driving around for maybe 30 minutes in 91 degree heat. Im pretty sure I burped the radiator right after filling it with new coolant and water. Bottle is still with fluid during and after engine heats up and cools down.

I was driving around doing some errands and then the jeep died. Same thing as last time..... I got it started again only to have it die again. I got it started and drove it thru the parking lot up to the stop sign where it died (230feet). I was unable to get her started.... she finally started and I made it another 150feet to a red light at a major intersection... it would not start at all now... people are getting pissed... finally starts and I make it another block and a half and she dies... I coast into a car wash... pull into a stall.... Temp gauge says she is at 210 degrees.
Call up a friend and he says to do a diagnostic by turning the key on then off then on then off then back on and leave it on and the light will flash the code.... mmmmm? Doesnt do anything on my model... guess it wasnt part of the program for my year and make....

Now when the jeep starts the rpm surges high and then flutters up and down kinda like a stair step effect all the way down to idle and then either stays running erradically or it dies.... still reminds me of a fuel delevery issue or like when my old chevy would vapor lock..

I put in some coins and sprayed down the radiator and hoses and bottle...... used 2 bucks worth and then sprayed the oil pan for a while.... got back in and it started fine and ran all the way home without dieing (15 minutes)... I pulled into the driving way where I turned the ignition off...

Ok... ready for more input... Im going to test the MAP tonight and anything else I am able to with the DMM.

thanks
 
Re: Aaaaaaarrrggggggggg!!!!!!!!1

CPS comes to mind for me as well. The connector is near the rear of the valve cover; pull it and clean it but be prepared to have to replace it.

The code checking sequence won't work for your 88, as it was only for the 'High Output' 4.0L with the new computer. Normally to get codes, you put the key on OFF and then rapidly do OFF-ON-OFF-ON-OFF-ON -it works better if the engine is fully warmed up though (although that doesn't help you any). For those with Chrysler 'puters in their 4.0L, check http://allpar.com/fix/codes.html
 
ok... I went out and started the engine and allowed it to idle... watched the temp gauge... as soon as it got up to 210 the engine died..... and would not start.... when it did start it rev'd up and mentioned above....
 
So it kinda dies when it comes out of cold loop if I'm reading you right, when it comes out of cold loop the emissions and computer kick in.
 
if i get the high alt CPS for the crank, do I also need to get it for the cam CPS?

The stealership has the high alt for 43 bucks.... is there a place i can get it on the internet for cheaper and after shipping isnt going to be the same price as the stealership?
 
Bet you a 6 pack its the throttle position sensor. Analytical troubleshooting teaches that for something to quit working, normally something had to change. You were cleaning the throttle body with carb cleaner. Did you clean the outside of the throttle body. Carb cleaner is the kiss of death, along with water, for the throttle position sensor. It can cause all the symptoms you have listed. CPS tends to me more of an all or nothing proposition. Your temp is fine for now and an over temp won't cause what you are describing.

If you have a voltmeter, I can scare up the diagnostic test to tell you if the TPS is the problem. I troubleshoot rather than throw parts at a problem. Otherwise you end up spending lots of money and if you replace more than one thing at a time, you never know what really fixed the problem.

A quick tip is that, if it does it and dies, open the hood and grasp the little lever arm on the tps and rotate it back and forth a bunch of times. It should work better for at least a little while. Sometimes you can just get by with pressing and releasing the gas pedal a bunch of times while the engine is shut off.
 
New Info............ Tested sensors... heres the Data.

I got home from work after 10pm and after a beer decided it was time to test the XJ to see what the problem might be.

Ok here is my data for the TPS:

D=.9vdc

I went ahead and added a second ground to this wire. Now it reads 0vdc.

A=4.66vdc
C=3.63vdc

I then adjusted the TPS to read 3.90vdc and check it all over again.

----------------------------------------------------------------------------------

MAP was tested using the Haynes manual...

A and B= 4.35 with engine not running
A and B= 1.90 with engine running

A and C= 5vdc

----------------------------------------------------------------------------------

MAT was tested:

reads 1.74Kohms cold and 1.0K ohms running temp.

----------------------------------------------------------------------------------

CPS was tested using the Haynes manual:

Reads 0.234K ohms and the book states it should read like an open circuit.


----------------------------------------------------------------------------------

Those are the only items I tested tonight. Let me know what you guys think.

Looks like the CPS is toast. I might just pull the TPS off and have it tested at Autozone to see if it passes.
 
If you ever have trouble with your converter locking and unlocking at 1/4 to 1/3 throttle, like multiple times in a series, you may want to remove the extra ground from the TCU circuit. Mine also has a standing voltage on the ground like .08 volts, tested with two different TCU´s. Just an assumption, but I´d guess there is a capacitor in the TCU, to deal with voltage spikes and such.
The three pole plug, is the side of the TPS, for the ECM motor. The side your testing is for the tranny. The four pole side is for the TCU, tranny. They work just the opposite of each other. You can test the three wire (engine) side, using the procedure for the stick shift.
Haven´t read the whole post, kinda pressed for time, may repeat some possibilties.
Plug the EGR vacume line at the EGR. Just to eliminate it as a possiblity.
Check the wiring where it continues, from the front of the fuel rail, down the front and under the motor, to the temp. sensor, knock sensor and O2 sensor, if it´s baking on the exhaust, it is or will cause all sorts of problems.
Take the big vacume line off of the intake manifold and suck, migh take a while, but it should eventually hold vacume.
Check the wiring for your CPS, where it goes into the harness, is it laying on the intake? Is it fryed or baked?
I´ve had the same problems you´re having at various times for different reasons. The EGR was bad, the hardline for the fuel rail was touching the exhaust, my balast resistor was cooked (unscrew it and look at the back side), wiring was cooked (in various places) and the O2 sensor was toast. And the craziest of all, had some water in the bottom of my distributor, when the motor got hot, it would vaporize and short the cap, when it was cold it would just collect in the bottom of the distributor, till the next run up to temperature.
Many of the senors are interrelated, hard to tell sometimes which one (or two) is causing the problems.
Good luck and happen hunting, been there done that.
 
Sorry typo, the standing voltage in my D wire for the four wire connector is .80 volts, close to the .9V you have. Read somewhere about voltage spikes messing with the torque converter lock and unlock, decided to leave it alone, just in case it was supposed to be like that. I checked every connector in the ground circuit, all the way to the TCU the .8 volt standing current is from resitance in the TCU (checked 2). Though I did clean and solder the ring connector at the dipstick holder for the TCU (TPS/TCU side).
Just checked my EGR transducer (after reading your thread/had a brain storm), both my EGR AND Transducer are leaking vacume. Moved my vacume plug (golf Tee) to the in side of the transducer, idle changed and stabilized :roll: .
I´d ask Jneary about adding a ground to the TPS/TCU circuit, see if it´s OK.

Your MAT values look wrong, Around .450 K at 160F and 3.4 K at 70F. Just checked mine it was 3.76 at 74F.
 
your readings seem like the map is working, i would tend to believe the egr is bad. sometimes when the cat convertor is starting to go bad, backpressure heats the egr transducer up and starts to melt it. thats what i am leaning toward especially if it wont idle and you have to keep it running by accelerating. if it was a fuel filter problem it wouldnt run when accelerating, thats when it needs more fuel and it would be starving the engine of fuel then. i would be prepared to replace the egr valve and possibly the convertor.i also recommend the factory replacement if so needed
 
Well yesterday I grabbed the cell phone and told my oldest to watch the phone cause I was going for a ride... Before I left I added a couple more grounding straps from the battery negative post to the body and engine.

I started the Jeep up.... started ok and idled fine... I sat in the driveway for about ten minutes then put the aw4 in reverse and backed out of the driveway. Seems ok for now... place it in drive and left.... drove around the neighborhood for a while before saying phawk it and taking off. I drove all over town for at least an hour. It ran fine. I decided to take her off the paved roads and into some construction figuring if it was going to crap out it would do it there... nope ran fine. I raced it a few times to see if pushing the engine would kill it... nope ran ok. I then decided to go home. Overall was out for at least 90 minutes.

I am going to take her out this evening for a test spin. Will have the kids with me.... I know its going to crap out now... but maybe its fixed? I certainly hope so.
 
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