Stalling problems

All good suggestions, but when the problem is so intermittent, it can be easy to overlook the cause or to disturb it enough that it will not act up for a while.

A grounded wire for a sensor should be detected by the computer. Same for an open wire for the IAC. Its position is not monitored; only the wires are monitored for continuity, so there should be a related fault code but only if it acts up long enough.

Doc,

I can tell, that you can tell, that I love you man!

I really do not want people to think I am all about negative.

My scale starts at "zero", there is no negative, any improvement is Positive,......anything down hill from that, is negative.

I do, every now and then, get some satisfaction, when I answer some posts. Really makes me feel good! And yes, I get a "warm fuzzy"! you will surely be able to detect it in this link.

https://www.2carpros.com/questions/2000-jeep-grand-cherokee-has-lost-its-mind

This is all I have to offer. I will still get an e-mail notifications, as you continue.

The Medic

The 1594 code refers to "charging system voltage too high". The voltage regulator is built into the engine computer and gives very little trouble on its own. There is one wire between the alternator and computer that can become grounded but that will set a different code, "alternator field circuit not switching properly". I would sooner suspect the system voltage sensing wire to the computer has a bad or corroded connection or loose terminal in the plug that is making the computer think system voltage is too low, then it commands the voltage regulator to increase alternator output.

Regardless of what is happening, the place to start is by measuring battery voltage while the engine is running. Use an inexpensive digital voltmeter. Proper voltage is between 13.75 and 14.75 volts. It will have to reach at least 16.0 volts before setting code 1594. That problem is not related to stalling or hard starting, however, suppose a wire harness fell off its clip and onto hot exhaust parts or is rubbing on a sharp metal bracket. If the alternator field control wire is touching something metal now, maybe the wire next to it in the harness is doing the same thing and is related to the stalling issue. That is why I always told my students it is never acceptable to just run a new wire to fix a problem. I required them to find exactly what was wrong with the original wire because that often exposed a different problem that was going to act up in the near future.

The other two codes refer to ignition coils one and two not reaching a high enough current flow, suggesting a break in the wire going to them. I would be looking for a connector with corroded pins or a stretched pin that is making intermittent contact with the mating pin. Connector pins can be aggravated by anything that causes the engine to shift position, such as accelerating, turning, coasting, or driving over bumpy roads.

You are doing yourself a disservice by piggybacking on this thread for a couple of reasons. First of all, there are a lot of really smart experts here who are not going to even see your problem or be able to reply because only those of us who replied previously will get an automated e-mail directing us back here when any reply is posted. You are losing the chance to have your question read by those other people.

Second, erasing fault codes does not make the problem go away. Mechanics want that information and will often tell owners to not come back until the check engine light has turned on or a code is set in memory so they have that to work with.

What is needed here is a full scanner, not just a code reader. Scanners display live data and will show if the engine computer is turning the automatic shutdown (ASD) relay off when the engine stalls, and if so, is it due to a missing signal from the cam or crank sensor? The scanner will also let you trigger each ignition coil and each injector to see if those circuits are working or if something is causing the computer to shut down to protect those circuits.

Beyond that, I would copy and paste your question into a new post so everyone gets a chance to read it and respond. I am not much of a Jeep expert. There are a lot of people here who can give you a better answer.

CJ might have thought you started a new question after we had already been in an on-going conversation. He does think I am a genius. I have lots of people fooled.

What you might look into is checking at some auto parts stores that borrow or rent tools to see if they have a scanner available. I use the Chrysler DRB3 but it is very expensive. Being one of the newer versions, it only works on 1998 and newer vehicles, but with additional plug-in cards it will work on all Chrysler products back to 1983 models and it can do all emissions-related stuff on any 1996 and newer brand of car sold in the U.S. For that reason a lot of independent shops bought them too. If you want to look into owning one of them, check eBay. I sold three of them there to pay for the one I kept.

Most of the better aftermarket scanners cost in the area of $3,000.00 but they have to be updated regularly. Only consider owning one if you plan on doing all of your own diagnostics for years to come. Also, by the 2004 models the DRB3 was obsolete. A different model scanner is needed for those vehicles.

The scanner will list the cam and crank sensors with "no" or "present" to show if signals are coming from both sensors when it won't start. It will also show if the ASD relay is being turned on.

One thing that is not monitored is fuel pressure. I am suspecting an intermittent pump failure right now with my 1988 Grand Caravan. It has stalled four or five times in the last six months, and twice it took some work to get it restarted. I still had great spark but pressure at the fuel test port seemed way too low, and one time I also cycled the ignition switch three times to run the pump for its one-second burst each time. That got it started again and that is my clue it is a pump problem.

Chrysler fuel pumps are built to very tight clearances to make them much quieter than those of other manufacturers but that also makes them more prone to locking up from microscopic debris in the tank. Often people run into repeat failures of four or five new pumps within a month or two, then out of desperation they by a new pump from the dealer and have no more problems. In reality it is not the aftermarket pumps that are bad; it is that all that debris got collected in the first pumps, then by the time they bought the pump from the dealer, that debris was gone. In fact, NAPA buys their Chrysler pumps from the same supplier Chrysler buys them from so you are actually getting a factory pump from them. Many mechanics now take gas tanks to radiator repair shops to have them steam-cleaned when they are replacing the pump.

The clinker to this story is when Chrysler fuel pumps quit, they usually fail to start up, and once they do start up, they rarely quit while they are running. GM pumps are the opposite. They will stop without warning and let you sit on the side of the road.

The best I can suggest for finding an intermittent pump problem is to install a pressure test gauge and clip it under the right wiper arm so you can see what happens to pressure when the engine stalls. That is what I am going to do with mine, when I can find the stupid thing!

Alright lets see what we can all do here. Rent or get a scan-tool, run it through and report back any of your findings. We all start here.

Does it start right back up when it stalls? What is the exact CPS code it is giving and have you checked the interrupter/reluctor rings on the crankshaft?

Check/monitor the fuel pressure if its within specs if it is the fuel pump it will show as a sore thumb when the fuel pressure starts dropping real fast before the engine stalls. Also, the ignition switch could have an internal problem when it heats up to a certain temperature it break opens taking out the ignition system

I have no idea what an interrupter/reluctor ring: The CPS tracks the reluctor on the crankshaft.

Have you check the CPS wiring back to the computer?

I am CJ kind guy, if you saw me above you already know.

I have been here quite some time, i read up on a good bit of the problems dealing with the other Jeeps. Many times i have seen a new crankshaft sensor fix the issue (in the forums).

I have a friend in Arizona, who had the same "wait thirty minutes to an hour" and it would bust off and run. He is sorta of "tight and lazy", and had his trips measured and stop timed, so that his rig would continue to get him around locally.

I suggested throwing the part at it, before he took it to a shop. His wife managed several apartment complexes and he was "elected" maintenance man. Just with his mechanical (non-automotive) skills he was able to do this job himself.

It looks really expensive.

Http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_crankshaft-sensor-bwd_18260313-p_762_r%7cgrpsensams_____

Maybe there is a certain technique to install one 100% correctly. In the factory manual?

I rely on my manuals for "law" (especially factory paper manual) "word of mouth" is just a "guide" or layman's terms for me to better understand the manual.

Do you have a manual?

Would you like access to the factory manuals?

The Medic

You friend is misinformed about the check engine light. When that light turns on while driving, there eill be a fault code in memory. Chrysler is very good about that. GM's can have the light turn on when the computer is just watching a developing problem. They call those "pending" codes. Those are why GM owners are often frustrated by that light turning on all the time.

When the light turns on, the code is related to something that could adversely affect emissions. There are other codes that can be set that do not turn the light on. Very minor problems do not turn the light on. For minor intermittent problems that affect emissions, the light will turn off while you are driving if the problem clears up. For more important problems that clear up, the light will stay on until you turn the ignition switch off and restart the engine, then it will remain off until that problem occurs again. For still more serious problems that clear up, the light will always be on even after restarting the engine. The highest level is when the check engine light is flashing. That means too much raw fuel is entering the exhaust system and is going to overheat the catalytic converter and damage it.

I use the Chrysler DRB3 scanner on all of my vehicles because it does more than any aftermarket equipment. One of the things it will display is a "no" or "present" for the cam and crank sensors. If you select the "no start" menu and drive until the stalling occurs, it will show instantly which signal was lost. It will also show other things that can cause that problem. For example, it will list the automatic shutdown (ASD) relay. If that is still on while you are coasting to a stop, you had to have lost fuel pressure or spark, but not both. If the ASD relay is off, both fuel pressure and spark will be lost. If the twelve volt feed to the engine computer is lost, you would suspect an overheated contact in the ignition switch. No code would be set for that because that is the same as turning that switch off which is a normal condition. Those types of things can help you find the circuit that has the intermittent problem. Without a scanner there is just way too many circuits to pick at random hoping to find the correct one to diagnose.