Randomly dying 99 TJ

[CharlesHS]

I agree with Mac.... on a possible dirty IAC solenoid or where the TB seating surface of the IAC disc.
With the engine running remove the air intake tube from the TB top, find the port just above the throttle plate and spray throttlebody cleaner (Seafoam) into the port.
Do not operate the throttle, spray small amounts of cleaner into the port without causing the engine to stall.
Perform these steps at least six times and then let the engine idle.
Take the Jeep for a drive and to determine if the problem still exists.

You said that the wiring harness was inspected and repaired...
Where was that problem ?
There is common wiring harness problem where the ECU communication harness that is run along the firewall and curves around the threaded head stud in the right rear corner of the head. The threads are know to rub thru the split wire loom and wiring insulation causing the bare copper wiring to ground out and engine stop running.
Inspect this area carefully...
My solution to alleviate this problem was to install a spark plug boot over the threaded head stud.

 

[TSteve-O]

634105[/ATTACH]

-Mac

 

[TSteve-O]

I

I agree with Mac.... on a possible dirty IAC solenoid or where the TB seating surface of the IAC disc.
With the engine running remove the air intake tube from the TB top, find the port just above the throttle plate and spray throttlebody cleaner (Seafoam) into the port.
Do not operate the throttle, spray small amounts of cleaner into the port without causing the engine to stall.
Perform these steps at least six times and then let the engine idle.
Take the Jeep for a drive and to determine if the problem still exists.

Gonna try tomorrow, I've spent hours after work today just checking things, I gotta pickup some seafoam anyway. Will hit it tomorrow and see.

 

[TSteve-O]

I agree with Mac.... on a possible dirty IAC solenoid or where the TB seating surface of the IAC disc.
With the engine running remove the air intake tube from the TB top, find the port just above the throttle plate and spray throttlebody cleaner (Seafoam) into the port.
Do not operate the throttle, spray small amounts of cleaner into the port without causing the engine to stall.
Perform these steps at least six times and then let the engine idle.
Take the Jeep for a drive and to determine if the problem still exists.

You said that the wiring harness was inspected and repaired...
Where was that problem ?
There is common wiring harness problem where the ECU communication harness that is run along the firewall and curves around the threaded head stud in the right rear corner of the head. The threads are know to rub thru the split wire loom and wiring insulation causing the bare copper wiring to ground out and engine stop running.
Inspect this area carefully...
My solution to alleviate this problem was to install a spark plug boot over the threaded head stud.

For the communication harness that runs along the firewall, I will double check it tomorrow, but i believe it was all still sealed up n good.

 

[macleanflood]

For the communication harness that runs along the firewall, I will double check it tomorrow, but i believe it was all still sealed up n good.

Sealed up isn't an indicator the wires inside are intact. I've often found chaffed wires minus insulation touching intermittently or fully seperated wires. These were not quality wiring harnesses.

Realistically you should get the wiring diagrams out and continuity and ohm check every wire from connector to connector. But that takes forever.

Sometimes delooming the entire harness and visually inspecting and running your hand down each wire is the way to go.

-Mac

 

[GregBelleville]

I'll check that. Just the connection to the coil pack? Or all the way back to the wiring harness?

This connector was my problem

 

[TSteve-O]

After a thorough cleaning of the sensors on the throttlebody and itself, it has had no stalls. Yesterday and today. Im going to keep an eye on it and see, but fingers and thankyou for all who have given me pointers up to now.

 

[TSteve-O]

Alright yall, been a busy few days recently, but its been crank no start as of Wednesday last week.

I was leaving for home from work after it sit for stleast 4 hours or so and she started, and died immediately. I then restarted, and it fired up, but rpms were erratic and she definitely didnt want tk keep running, and then spluttered and shut off. I waited about another 30 minutes and tried to crank again, and she fired right up. So I opted to save me a tow and drive it home. About halfway home I was at a stopsign and she died again. Fired right back up no issue. And made it the rest of the way home.

Come Thursday I opted to tske my other car for the day, however I did try to crank and now we're at the current stage of crank, and no start.

Since then, I have tested many splice locations related to ignition mostly, and voltages checked out according to sticky thread manuals, although it was annoying to test dg/lg wire to coil connector without a second person it checked out.

I also replaced mt throttlebody, iac, map, and coil, nothing changing. I've also got a new tps on the way to be thorough.

It does seem im getting correct voltage to the wires for asd circuit, and my ground tests didnt show above 5 ohms resistance.
I have a new distributor on the way because im pretty sure the current one is the OG from 99, its a pain to find parts here for this thing so I figure I'll tske a whole new distributor, and have the old as spare.

Recap on the fuel, pressure is 45, and whole fuel pump primes as it should, and connector to it has correct volts.
This sumb will not start with starter fluid either, but it does sound closer to actually firing but still nada.
I also inspected all fuses related to ASD, I believe #9 in engine fuse box and #18 in glove box, and no blown fuses, and correct voltage to their connections.

I may now need a new battery as the cranking intermittently to test things has drained mt current one. I have a jumperbox but no tricklecharger currently.

So thats the most of it i believe. I re-inspected my cps and put it back in, I've read about that thing going bad if there isn't a spacer on it upon starting it for its first crank, but im not sure.

Any questions I'll answer in due time. But this is pretty much where I stand right now.

 

[TSteve-O]

Just so we are tracking as well, this is a 99 tj 4.0 automatic Sahara, japanese RHD model, (not much changes for that but I'll mention it.)

 

[TSteve-O]

Another sidenote,
I had the taillights harnesses and such in the rear tubs Rewired last August, and it wasn't long after that when I noticed this issue overall became more prominent (the stalling while idling/driving) although back then when I had the issue it always started right up.
Could be a coincidence, but im going to mention it here.

 

[TSteve-O]

Finally looking at the wiring starting from pcm, admittedly only code shown so far is P0320, crankshaft no signal at pcm, so im really just slowly learning more about the wiring and such. It seems to me some splices were made previously at some point, with the far left connector, or 4th picture having what seems to be very much newer wiring. And electrical tape going all around it. This jeep has definitely had aome hard-core rewiring done in the past I think. Not done by previous owner I bought from though, so id have to track down who may have done it.
Im currently waiting on new plugs as well as the distributor, and plug wires. So this old girl probably isn't going to be turned over for the time being. I also have an extra battery that should crank it, for when that time happens, and another nice new battery fully up to spec for the cold cranks in winter coming up.
Plugs look like some hell though too.
I also attached some more pictures of removed parts and such.
The oil and oil filter looks like hell too, so I'll be draining the oil once I get the proper oil filter here, drained what appears to be excess as well, I think it had a good liter and a half extra over what it should've had. Admittedly even small things like that I haven't done much of to this jeep being that most of the little over year I've owned it I have been gone and not using it.
If any of yall have any input in regards to this reply, or others let me know!

 

[TSteve-O]

ALRIGHT FELLAS. Thanks to you all, and a little digging, it would seem that the cps was going faulty due to being too deep into its mounting socket, I did some research, and there does need to be some space between the cps and whatever its tracking, I forget the name. (flywheel?) I ordered a new cps, came in today, I changed oil, oil flush, new filter, new air filter, new plugs, and wires, (waiting on a less corroded dizzy cap) and shes running smoother than butter. So THANKYOU for all the advice, I will be nicely closing back up all my wiring, and finding a way to secure some of the harnesses better as PM to avoid any electrical issues down the road.
I will attach a picture of the old cps, it looks like it was caught by the teeth of what its supposed to be monitoring, so in my learning from this, id say put the new cps you install in the hole, finger tighten the mounting bolt almost all the way, pull the cps outward against the washer kn the bolt, then tighten down, will update if we have our stalling issue again, but she seems pretty good as of now!

Cheers fellas.

 

[TSteve-O]

Old (new cps)