XJ stalling at random times. (another one)

Hello, I have been searching google and all of the forums for about 6 months trying to get my jeep fixed. Any additional help would be appreciated.

Symptoms started out as: frequent stalling. frequent backfires, or sputtering on acceleration leading to stalling. So I started some research. Replaced some parts. Symptoms go away for a week then they start up again. Currently its the most well behaved I have ever had it. It only breaks down once a day on average now. Always starts back up I just tap it into neutral and start it as its rolling.

list of new parts.
cap, rotor, wires, plugs,
camshaft position pickup located in dstributor
battery,
CPS
TPS
Idle air sensor
coolant sensor
replaced exhaust and both o2 sensors,
new brake booster as it had a leak (no other vacuum leaks)
upgraded to 4 hole injectors from dodge caravan

So Ive replaced everything I can think of, it runs perfectly normal most of the time. Then sometimes its hard to start (need to give it some gas and hold it for a minute in order for the TPS to catch it before it dies)

Sometimes when going down a specific hill by my house it dies. sometimes when going up the same hill it dies, always when I'm turning. IT ALWAYS DIES WHEN TURNING.
Most of the time the RPM's just bounce up and down when its acting up. Driving down the street, let off of the gas and the RPMs just bounce from 0-700ish trying to stay alive. Put it in Neutral and tap the gas to keep it going.

Any ideas? I have searched and replaced parts for the last 6 months. Winter is coming and a baby on the way. I can't keep having it break down. Thanks guys.

First would be what year? Second would be if you have put a scanner on it? Third did you buy genuine Mopar parts?

Fourth, did you buy Bosch or NTK O2 sensors ?

Have you inspected all the engine wire harnesses, including the O2 sensor wire harnesses for melted or chafed wire insulation and damaged/broken wires ?

And finally, hard starting and having to feather the gas pedal to get the engine to run, strongly suggests low voltage, typically from poor charging, a faulty battery, or loose corroded alternator/battery wire and connections.


Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Copper wires should be copper color, not black or green. Battery terminals and battery wire connectors should bright silver, not dull gray and corroded. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush, and clean until shiny the cable/wire ends and whatever they bolt onto.

Jeeps do not tolerate low voltage, bad wire connections, or poor grounds.


Place your DVOM (Digital Volt Ohm Multi-Meter) on the 20 volt scale. First check battery voltage by placing your multi-meter's positive lead on the battery's positive post ( the actual post, not the clamp ) and the negative lead on the negative post. You need a minimum of 12 volts to continue testing. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your positive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then you have excessive voltage drop in the starter circuit.

Typical voltage drop maximums:
• starter circuit (including starter solenoid) = 0.60 volt
• battery post to battery terminal end = zero volts
• battery main cable (measured end to end) 0.20 volt
• starter solenoid = 0.20 volt
• battery negative post to alternator metal frame = 0.20 volt
• negative main cable to engine block = 0.20 volt
• negative battery post to starter metal frame = 0.30
• battery positive post to alternator b+stud = 0.5 volt with maximum charging load applied (all accessories turned on)

Doing it when turning is a clue. I would look at the entire wiring harness for anywhere that might be rubbing or hitting anything. Also take apart any ground connections and clean them.

Dies while turning or going up or down a hill -- I'd be looking at the fuel pump/fuel tank -- The screen at the bottom of the fuel pickup is clogged

Does it make a difference if there is a full tank of fuel vs a quarter tank of fuel?

okay. i have done a few things. Sorry for not replying, I am a full time nursing student and I dont always have time to post. School is on break.


Okay. It is a 1999. 4.0.



It stops running daily. Now, it does it all the time. Sitting a stop light, going down hills, etc. Yesterday I was trying to find a place to park at work. I pull up to a stop sign, it dies. I went to start it.....no crank.
So I get out and look at the fuses under the hood. Jump back in and it started back up. Worked, went to the gym on my break. Came back out and no crank. I look at it for about 20 minutes and can not get it to crank. I hear the relay click but the starter does not engage.
So I got a ride. Went and got a starter. Got back to my jeep and decided to just try and see if it would start. And it did. I did nothing to it. Just get in and it went.
Ideas on that?

I noticed the ignition switch seemed like I had to push it farther than normal to get it to turn over. I took apart the steering column. Removed the ignition tubler, and pulled the ignition switch out so I can start it with a screwdriver. Starts up just fine.



But it still dies!!!! I took off with the column in pieces to go get a new ignition tumbler. Died 3 times and I decided f' it I was going home.


Update on work. All ground wires have been cleaned up or replaced in the engine bay.
Checked Fuel pressure. At idle the needle rapidly bounces between 40 and 50. With the gas pedal pushed it holds a solid 50psi.



I need help with this.

Clicking sounds ( or just one single click ), or nothing at all from the starter, suspect dirty, loose or corroded battery and/or starter cables or connections.

Starter works as usual and you have a no-start, suspect the Crankshaft Position Sensor. Random unexplained stalling also point to the CPS.

so... start her up.
Go wiggle all the wires under the hood. CAREFULLY !!.
When she starts to stumble or die. u have found ur issue. If u check all wires and no change.
Replace Cps.
Check fuel pressure. (Install yourself a perm gauge. Its INVALUABLE !)
check grounds.

I know checking wire has already been suggested. Let me add that as you do that one thing to be looking for is any wire that gets near the exhaust. If a wire can touch the exhaust the insulation will melt and the wire will ground out (thus taking out some component). Let things cool off and that melted insulation may let go of the exhaust and things will work again, until you make that turn or whatever else puts that wire in contact with the exhaust.


That is just one potential scenario, but that is the sort of thing you are looking for as you examine your wires.


How does the wiring harness look under the dash? Lots of evidence of previous owners hacking their way around to install stereo and alarm components? If yes, that would be another area to spend some time looking for an exposed bit of wiring, perhaps even a cut end (now a loose wire) that is able to brush against the metal dash supports.

okay. Just one click sound from the relay...thats when it wouldnt start.
I changed out the CPS when it wouldnt start 5 months ago. Cured that problem. Will look at and test tomorrow.



So, I have done the start and wiggle. I will try again tomorrow.


I heard that about the exhaust. I will give it a good look.

Wires under the dash are in place and proper. Windshield leaks so I get some water on the floor mat. I dont see that it is running into any wires.



Thank you everyone for the responses. I will update tomorrow.

I have a few comments. Electrical-mechanical relays are supposed to "latch/close" and stay "latched/closed" when energized. Over time, either from dirt getting into the relay or from contact corrosion, the resistance of the contact surfaces increases. The relay's contacts will then "chatter" randomly and not stay "latched" ; i.e.the relay is latching and unlatching during operation.

I suggest replacing the fuel pump relay and starter relays and see it that improves things. Likewise, try running a separate ground wire from the battery ground terminal to the starter mounting bolt and see if that helps.

Best regards,

CJR

Hi! So I replaced the relays for fuel pump and starter. And knock on wood, it hasn’t stumbled and died yet.




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