1998 Jeep Grand Cherokee stalling

The ticking you're hearing is most likely the valve that controls the purge flow. It will cycle on and off about twice per second.

Since you didn't list the engine size I don't know if yours has one or multiple ignition coils. If you have one for each cylinder you should get a fault code stating which coil circuit has the problem. You can switch that coil with one of the other ones to see if the problem moves to that new cylinder.

Most mechanics have scanners that display live data AND have a record / playback feature. The record button is pressed when the stalling occurs, then the event can be played back slowly later to see what is changing or happening. Because that data travels through the scanner's memory, the recording actually starts a couple of seconds before the button is pressed.

You also didn't say when this stalling occurs. Is it while driving at a steady speed? Just when coming to a stop? Will the engine restart right away? One common but elusive problem is stalling just as you start to coast from highway speed.

It's not very likely the evaporative emissions system can cause stalling. That system mainly takes care of gas fumes from the gas expanding in the tank.

If the engine stalls while driving at a steady speed that is almost always due to the crankshaft position sensor or camshaft position sensor. When they fail intermittently it is because they are failing by becoming heat-sensitive. The engine will not restart until they cool down for about a half hour. Most commonly this occurs right after a hot engine has been stopped for a few minutes. That gives the heat time to migrate up to those sensors. A mechanic would see this on his scanner during the restart attempts. One sensor signal would be listed as "present" and one would be listed as "no".

Unlike GM fuel pumps that typically fail while you're driving and let you sitting on the side of the road, Chrysler pumps will fail to start up when you start the engine. Once they DO start up they rarely quit while you're driving. If you drive with a fuel pressure gauge clipped to the radio antenna, (as I've been doing for the last year on my '88 Grand Caravan daily driver), if you see the pressure slowly drop, particularly when coasting from highway speed or when pulling a heavy load, suspect a plugged pickup screen. In my case it was snapped onto the fuel pump assembly and was real easy and cheap to replace.

If the stalling only occurs when you come to a stop, and the engine will start up again right away, that is due to the battery being recently disconnected or run dead. There's an easy fix for that.

Simple code readers don't do live sensor data. You don't need a code reader anyway. Chrysler makes reading Engine Computer codes real easy. You cycle the ignition switch three times within five seconds from "off" to "run", leave it in "run", then watch the code numbers show up in the odometer display.

There are some code readers out there that are getting a little more involved and may provide sensor data, but all I've ever used are full scanners. I have a Chrysler DRB3 because with extra plug-in cards it will work on the older stuff I drive and it can access emissions-related data on all car brands sold in the U.S. After 1995.

The camshaft position sensor is in the distributor. You replaced the crankshaft position sensor which has had a higher failure rate. Was there a thick paper spacer stuck on the end when you installed it, or was there a thin plastic rib molded onto the end? Those set the critical air gap. If that gap is not right it can cause intermittent stalling with no set pattern. I had one that I thought I was too smart and I didn't use that spacer. The engine ran fine for two weeks, then started stalling intermittently. All I had to do was reinstall it with the spacer.

The spacer will slide off as soon as the engine is started, and the plastic rib will wear down over time. With either design, if you reinstall a used sensor, if it has the rib you are to cut the remaining part off, then use a paper spacer.

You shouldn't be thinking at all about the evaporative emissions system. That won't cause stalling. If your scanner or code reader shows the camshaft position sensor and crankshaft position sensor states, monitor those while you're driving and when the stalling occurs. If you see one of the signals suddenly listed as "no" or something equivalent, that is the circuit to diagnose. Replacing the sensor will only solve the problem about half of the time. The other times it is due to a corroded splice or stretched terminal making poor contact in a connector. Often those will not set a fault code because they don't act up long enough before the engine stops running. You're also unlikely to get a crankshaft sensor code when the air gap is wrong. The signal generated will be too small to keep the ASD relay on but big enough to be detected and prevent a code from setting.

You can also monitor the automatic shutdown (ASD) relay. It will turn on for one second after turning on the ignition switch, then again whenever there is engine rotation, (cranking or running). That relay is turned on by the Engine Computer when it receives signals from those two sensors. If the relay turns off while you're driving, that is due to a problem with one of those sensors. That relay supplies power to the ignition coil, injectors, and fuel pump or pump relay.

That sounds like a generic display where they are filling in the available information. I don't know if "fuel system 1" is for the automatic shutdown relay or the fuel pump relay. Either one should turn on for one second when you turn on the ignition switch. That can be hard or impossible to see with a scanner because they stop receiving information when the ignition switch is off, and even when it's on they respond too slowly. The display updates WAY slower than the information that is transmitted between the computers on the car.

Of more importance is what happens to that value when the engine stalls? That can also be hard to catch because the ASD relay and the fuel pump relay WILL turn off when the engine stops rotating. Your best hope is to have the engine stall at highway speed. The engine will keep rotating down to about 15 - 20 mph giving you time to watch the display. If that fuel system 1 stays "closed" while you're coasting, you have a spark OR a fuel supply problem. If it switches to "open", (off), and the engine is still rotating, you have a problem that is affecting spark AND the fuel supply system, which usually means the cam or crank sensor.

Your mechanic was referring to the crankshaft position sensor and the camshaft position sensor. Depending on the engine size and year, some engines will stall when one of them fails, some will continue to run when one fails, but the engine won't restart once stopped, and some will run in "back-up" mode when one fails. Those sensors often fail by becoming heat-sensitive, then they will work again after they cool down for about an hour. While driving, natural air flow keeps the sensors cool. When a hot engine is stopped, "hot soak" causes the engine heat to migrate up to the sensors, resulting in a crank / no-start after a few minutes.

The Engine Computer is always a possibility, and was real common on early '90s GM vehicles, but Chrysler has extremely little trouble with theirs. Way too many people blame the computer for everything, then can't understand why replacing it didn't fix the problem. The two vehicles in this story are perfect examples. The computer should be the last suspect on the list.