[Chris627]

After going back and reading my first post to the last post and all the replies in-between I found that I had omitted one piece of information. I am currently running this Jeep with a remanufactured computer that I bought from Auto Computer Exchange. In my original post I spoke about the shop saying that the computer was fried and that I needed a new one and that they then ordered the incorrect computer. Well, after speaking directly to the mechanic he assured me that this was the problem, so that is when I ordered a ECM(PCM) from the above company. Installing this “new” computer made no difference in the 30-minutes to stall problem I was having and continue to have. Below is a complete list of the troubleshooting I have done to date. If anyone can divine, from this list what the issue is I will be eternally grateful. If not it will be going to the dealership sometime Monday. Thanks
1. Crank Position Sensor replaced. The CPS has tested good
2. Cam Position Sensor replaced. Put the old one back with no change in problem
3. ECM(PCM) Replaced problem still happens Old or New
4. Removed and cleaned Throttle Body
5. Tested the TBS O.K.
6. Tested all 4 of the O2 sensors O.K.
7. Tested Coolant sensor O.K.
8. Tested MAT Sensor O.K.
9. Tested the Coil Rail at room temp O.K.
10. Tested and swapped the ASD Relay O.K.
11. Tested and Swapped Fuel Pump Relay O.K.
12. Cleaned went through every connection both electrical and vacuum found nothing obviously wrong
13. Tested fuel pressure looks a little weird but I think it is O.K. see results; 0 PSI cold engine key not turned
46PSI cold engine key turned to on position
46-48PSI engine started still cold at idle warming-up
44-50PSI bouncing up and down engine at operating temperature.
48PSI when motor dies.
The last test I have to do is from a post on another site and involves the coil. This will be the last test and is either a pass/fail. Here is the test; Unplug wire connector from coil rail and check to see if you are getting 250-1000 ohms after it dies through the harness.
I’ll also be pulling the coil rail to see if the resistance has changed.

Thank you all for your help

[gary92yj]

I always shoot engine starter in the filter and see if i have ignition. If so, forget the coil idea, it's a fuel issue. I wonder if it's an emission issue. If the egr valve opens at low rpm it will kill the motor. Try unplugging the vacuum lines to it and see if that helps. The map sensor could also cause a lot of trouble. My neon had the egr stick open,causing a lack of vacuum in the intake. The map sensor thinks the throttle is more open than it is and tries to compensate,overrichening the fuel. But no codes pointed to any sensors. If the computer loses a sensor signal all together while warm and in open-loop mode, it will ignore it and work with all the other readings. I unplug 1 sensor at a time until things improve to point me in the right direction. Not very scientific but usually effective.

[Chris627]

O.K. I'll give this a try.

[tjwalker]

No EGR valve on later model XJs.

[Chris627]

Originally Posted by gary92yj

I always shoot engine starter in the filter and see if i have ignition. If so, forget the coil idea, it's a fuel issue. I wonder if it's an emission issue. If the egr valve opens at low rpm it will kill the motor. Try unplugging the vacuum lines to it and see if that helps. The map sensor could also cause a lot of trouble. My neon had the egr stick open,causing a lack of vacuum in the intake. The map sensor thinks the throttle is more open than it is and tries to compensate,overrichening the fuel. But no codes pointed to any sensors. If the computer loses a sensor signal all together while warm and in open-loop mode, it will ignore it and work with all the other readings. I unplug 1 sensor at a time until things improve to point me in the right direction. Not very scientific but usually effective.

I did all these tests with the engine warm and just below the 30minute mark.
Here are the results of my pull 1-sensor at a time test;
MAP Sensor died 10min. after it was started
IAT Sensor died after 30min.
IAC Sensor died after 16min.
TPS Sensor died after 10min. NO CHECK LIGHT CAME ON
Coolant Sensor 45min then died
There is no EGR valve.
Each time it died it would crank and not start. I then shot a little starter fluid into the intake and it fired right up. So, thanks for at least helping me eliminate the fried coil idea.
After all this was done I hooked up the fuel pressure gauge and I'm still spooked by the bounce of the needle. If you look at post #16, I put my the readings there. The high at the time I wrote post #16 was 50PSI it is now at 52PSI the low is still 44PSI. Is the pressure supposed to fluctuate this much? I would think that having an electric fuel pump that the needle would be fairly steady. Assuming that the regulator was working properly. Could this be the cause of the stalling? Is there any way of testing any of the fuel parts in the tank without actually dropping the tank? Maybe through the electrical connector? Thanks for the help.

[tjwalker]

Originally Posted by Chris627

Each time it died it would crank and not start. I then shot a little starter fluid into the intake and it fired right up.

I copied this quote from you as it seems to be your biggest clue in my opinion.

IF when it stalls and doesn't start, you can "consistently" start it by spraying some starter fluid into the intake, you HAVE TO concentrate on this being a fuel delivery problem. I'd try this starting fluid test at least 3 times when it stalls just to make sure that it isn't a coincidence that it started the one time with the starting fluid.

If you can consistently start it with starting fluid, I'd think about it this way. By spraying starting fluid, what part of the starting equation (spark + fuel = ignition) have you changed? Only the fuel part. The ignition part was never messed with.

While your pressure numbers don't seem to be too alarming, your fuel pump assembly could still be suspect. Priming it with a bit of starter fluid may be enough to get it started, after which it stays running on its own. Just brainstorming here.

There are some comprehensive fuel delivery testing procedures in the factory service manual. Performing them may be of some value here.

These type of problems can be frustrating but I applaud your tenacity. Stay on it!!!

[Chris627]

Originally Posted by tjwalker

I copied this quote from you as it seems to be your biggest clue in my opinion.

IF when it stalls and doesn't start, you can "consistently" start it by spraying some starter fluid into the intake, you HAVE TO concentrate on this being a fuel delivery problem. I'd try this starting fluid test at least 3 times when it stalls just to make sure that it isn't a coincidence that it started the one time with the starting fluid.

If you can consistently start it with starting fluid, I'd think about it this way. By spraying starting fluid, what part of the starting equation (spark + fuel = ignition) have you changed? Only the fuel part. The ignition part was never messed with.

While your pressure numbers don't seem to be too alarming, your fuel pump assembly could still be suspect. Priming it with a bit of starter fluid may be enough to get it started, after which it stays running on its own. Just brainstorming here.

There are some comprehensive fuel delivery testing procedures in the factory service manual. Performing them may be of some value here.

These type of problems can be frustrating but I applaud your tenacity. Stay on it!!!

The sickness continues,(see previous posts) even after replacing the fuel pump! I had to get away from the Jeep for awhile and get some perspective. I was not getting anywhere and the money seemed to be draining away without result.

Over the holidays I happened to be over at my brothers house helping unload gifts from my brother-in-laws trunk when I noticed he had an OBD-II tester in his trunk. Guess what I asked to borrow? The codes this thing had been kicking up, when it wanted to, were just the run of the mill crank & cam sensor and misfiring. Well I decided to drive it around with the code reader attached. The Jeep did what it normally does after a few miles and this time when the engine light came on I was ready. The codes I got are P0352 and P1391. The P1391 I have seen before, but the P0352 was new. My first question is does this mean the coil is bad or that I have a bad spark plug? My second question is should I replace the spark plugs first and give it a whirl or should I go for the whole works and get the coil with the sparks plugs? My third question is can the P0352 code be pointing to another component in the ignition system?

[tjwalker]

I may sound like a broken record here, but does your engine still start and run momentarily with starter fluid like it did in the past? That really is such a critical clue here IMHO. It eliminates so many things from the equation if it starts with starter fluid.

If it does start that way, that would for practical purposes, eliminate the crankshaft position sensor from the equation. If you have no crank signal, it will not fire, no matter how fuel is introduced.

I would put my efforts into another check of the camshaft position sensor AND ensure that the camshaft signal is making it into the computer (how handy are you with a meter) If that signal is inhibited somehow, the computer may not be sending fuel to your injectors.

[Chris627]

I'm pretty handy with the old meter at this point! What am I checking and where is it located?

[robhollar]

You shouldnt have any bounce. It might rise and fall +- 5 psi but if you have a bounce you more then likely have a pressure issue. I just had similar issues with my wifes 96 xj and changed it in about an hour. Replace the sock and filter too....Rob

[Chris627]

Fuel pump is not an issue anymore, I replaced it. See post #22 for current and continuing problem. Thanks for looking.
Chris

[grbjr87pioneer]

Will give 2nd opinion of coil problem!

[Chris627]

Originally Posted by tjwalker

I may sound like a broken record here, but does your engine still start and run momentarily with starter fluid like it did in the past? That really is such a critical clue here IMHO. It eliminates so many things from the equation if it starts with starter fluid.

If it does start that way, that would for practical purposes, eliminate the crankshaft position sensor from the equation. If you have no crank signal, it will not fire, no matter how fuel is introduced.

I would put my efforts into another check of the camshaft position sensor AND ensure that the camshaft signal is making it into the computer (how handy are you with a meter) If that signal is inhibited somehow, the computer may not be sending fuel to your injectors.

I spent some time checking all the connections that you mentioned. Everything appears to be mechanically sound. I then replaced the spark plugs with the OEM plugs, double checked the gap before installing, all was good. I figured that before this nightmare started, it was on my to do list anyway. Guess what happened next? The motor turns over but will not start. The starter fluid down the intake made no difference. What do you thinK?

[jdearmitt]

Try putting a new ignition coil in it.

[Chris627]

I'm thinking that this is the solution-THE $170.00 SOLUTION!

Thanks Man