doostica

I was advised to start another thread about this issue so here I am.....

I have replaced many many things on my Jeep in the past year and countless others in the past 3 yrs, all have been replaced with factory Mopar parts from a reputable Chrysler dealership unless the part is no longer made or just absurdly expensive yet in most cases, I still buy the Mopar oem part.

The Jeep starts up fine, no issues with that. Battery is brand new, less than 2 months old. Gold series battery from advance, Alternator replaced in December, starter was just replaced over the weekend. Idle Air Control valve and TPS were both just replaced as well. CPS was replaced back in Nov/December.

No matter if I am driving at 5 miles per hour pulling into my drive way or a parking space or 55 slowing down to a stop light, the thing dies at every single stop, I usually throw it into neutral before I get to a stop to keep this from happening..... It's an automatic, not a manual if that matters.

It used to be 8/10 times it would die, now it dies nearly every single time I come to a stop and oddly it also dies when I pull into a parking space. I can turn to pull it into a parking space and as soooon as I get in the space, it dies before I have a chance to shut the engine off. It doesn't sputter, just boom immediately the jeep is off. Starts back up every time with no issues.

I have replaced the fuel pump and fuel filter both back in December, thinking maybe they were the cause of this issue, but nope. Amongst many other things over the past year, This has been going on for close to a year now and I am ready to drive her off a beautiful cliff in the Mountains.

All help and suggestions would be appreciated, Thanks!

The Jeep gives me no codes.

freegdr

Does it idle ever?

jordan96xj

It sounds like your torque converter is failing to unlock during slow-downs and stops. That is probably why forcing it into neutral is helping it stay running. When the torque converter fails to unlock, it keeps the motor directly connected to the drive train, and as you slow down the drive train by applying brakes, it drags the motor down with it, instead of letting the motor spin at its own idle RPM (around 750-800 rpm).

If you have a tachometer or scanner, your can check for torque converter unlocking at speed. Just drive straight and level at about 55 mph in "D" drive. This should put you at about 1800-1900 rpm. Then while cruising, tap the brake pedal lightly. The torque converter should unlock, causing an immediate increase in RPM by about 300-500 rpm. Then after a few moments, it will return to the original RPM (1800-1900) as the torque converter locks back up again.

I don't know all of the reasons this can happen. Obviously the brake switch is involved, and I would imagine the throttle position sensor (TPS) and crankshaft position sensor (CPS) might also be read by the computer to make decisions as to when to command that the torque converter unlock. I'll have to study the FSM to find out if it provides more detailed information as to all of the conditions and sensors that should trip this behavior. You should do the same.

Failure modes would probably include things like:
1. Sensor problem causing the computer never to command the unlock
2. Computer commanding the unlock, but the transmission never getting the command.
3. Transmission getting the command, but failing to complete its behavior
4. Something purely mechanical, (not electrical or computer related)

doostica

FreeGDR-
Yes it idles without any issues when I first start it up. Before I back out of the parking space or driveway. However If I pull into a parking space after driving it or pulling into my driveway, which is about as level as I've ever seen a driveway, it always dies before I can even put it into park to let it idle, so it only idles when I start it up, before I take it out of park.


Jordan-
There is a tachometer on my dash, and I just replaced the tps last week and the cps yesterday. I live right by a state road, 27 and it's a long straight road for a good half hour. So you are saying to see if it fluctuates and increases by 300-500 rpm's if it does then do I let off the brake or do I just lightly tap the brake and let go?
--is this a good sign or a bad sign if it fluctuates up then back to lower rpms?
Is this the only way to test a torque converter?

nujeepguy

i think mine locks at 40-50. if you hit the gas at lower speeds the rpms jump as the tq slips.
when locked if you ease on the gas ,rps climb slow as the speed increases because its like a stick shift, no slipping.

shift to neut b4 stopping. it should idle. stop. drop into drive .it should idle while pulling. if it stalls, its stuck.

jordan96xj

It is normal and good for the torque converter (TC) to lock up once it has reached sufficient speed. However, it needs to unlock quickly under a variety of circumstances. For example, touching the brake pedal, abrupt reduction in engine rpm, etc. The computer senses these changes and takes care of commanding the TC to unlock. You normally wouldn't even notice it, its pretty subtle. But knowing that it is in fact unlocking, would be pretty helpful in your situation. So the procedure I gave you will help you determine that at least under one circumstance (touching the brake pedal) the TC unlocks as it should.

1. Drive straight and flat at 55mph in "D"
2. Note the tachometer RPMs
3. With your left foot, tap the brake pedal once (just enough to trigger the brake pedal switch, the same switch responsible for turning your brake lights on).
4. At that moment you should see the tachometer jump up by 300-500 rpm.
5. After a few moments (2-10 seconds-ish). The tachometer should drop back down to the originally noted RPM. (this is the TC locking back up - as it should)

If the TC unlocked properly when the brake pedal was tapped, it momentarily allows the motor to spin a little faster than the transmission, which can be seen on your tachometer as a brief but noticeable increase in engine RPM.

For more information on torque converters, and their lockup function, here is a video from Eric the Car Guy:

doostica

So I did what both of you suggested and everything checked out fine, so I am glad it's not the torque converter, I see it's quite pricey. I was watching many of Eric's videos on youtube the other night and had just looked the one you provided over the night prior and thought, I'll have to add that to my list of things to check, so thanks for the suggestion.

Any other items I should check? I am going to pick up some carb cleaner and search for a vacuum leak either tonight when I get home, or Friday, my day off.

I really appreciate all of your help and suggestions. I am so stumped, as this has been going on for so so long it's far past annoying, now it's just a part of my daily drive, although I am always worried having my little guy in the car we'll get stranded in the middle of nowhere.

OldTires

This is what the FSM says about Deceleration Mode on the 1996:



It sounds like the PCM is just cutting off the injectors because it is getting the wrong signal from a sensor or the PCM is gone bad. Because it happens when slowing down only I would focus on the listed procedure and sensors. I would not replace sensors that you recently replaced already and instead look for the ones that are old and haven't been replaced.

Have you pulled any codes?

If you start it when cold and go drive right away and then stop, does it stall then?

Have you tried taking it to a dealer for a diagnosis, if it doesn't cost an arm and leg?

I am wondering if the NSS could do this. Maybe more experienced members could opine on this.

OldTires

Also, what's your idle speed once warmed up? Does it fluctuate any from start to start or is it always steady at a certain number?

jordan96xj

OldTires,

That is a great addition to the thread. My next target would be a test of the TPS. I would also be observing the speedometer closely to see if there are any strange readings as the vehicle is slowing down (basically, looking for any weirdness coming from the vehicle speed sensor, though not a thorough test).

doostica,

If you do not already have an OBD2 scanner, I would get one. They can be had on amazon for cheap these days ($25 if you have an android phone to use). BAFX is the brand that I use. It will show a lot of data even on a 96 that can help shed light on what the computer is seeing under these conditions. On my 96, the throttle position reported by the computer is 16.9 at idle (foot off the pedal).

doostica

Actually I have an OBD I vehicle, it's the split year and mine is still an OBD I model, and my fuel pump is in the tank, which was just replaced along with the filter and the line. I can do the key trick and get codes, however for now, I am getting no codes. Crazy enough I just replaced the TPS back in December and just a few days ago replaced it again, both are Mopar which made no difference, my suspicion is, after watching eric the car guys video the other day (and suggested again today) to get carb cleaner and find out if there is a vacuum leak - I had a can but used the rest cleaning my throttle body which is amazingly clean now. I think something may be ready to die on me completely as tonight when I pulled in after coming home from work, It is making an rattling kind of noise, which probably has nothing to do with my dying randomly issue, I am sure, because eh this Jeep has been that way since I got her. LOL

-Thanks!
Jessica

doostica

I will check this in the morning and let ya know!

One thing I have never replaced is the map sensor, what exactly does it do? Let me re-ask this question....Would a failing or failed map sensor cause this dying issue?, as for what I know about the map sensor in general it is not listed as my issue being one that a failed map sensor would typically exhibit.

Another thing to note, I have only replaced one of the o2 sensors and this was in December, would the other be a possible cause?

doostica

I was wondering if there could be a clogged injector or just one that's gone bad that's causing the issue? What about this weird 2 little screws being too long stuff I read, is this real, should I unscrew them and which ones are they?

I have never taken it to the dealer, to spend $200 (what I was quoted by the 2 Jeep and Chrysler dealers nearest me, to have them tell me what's wrong for me is something I think I'd rather spend $200 on replacing things and learning along the way, which in a sense in my mind is "preventative maintenance" for any issues I could have been about to encounter in the future, now replaced with new parts. I have all the old parts, in the new parts boxes and all my receipts logs, etc...

If I start up the Jeep whether it's been after sitting all night and get up to go to work, or whether I've been driving it from place to place, it dies no matter how long it has or has not been driven, at every single stop. I am perplexed.

It did scream when I started it up tonight, then I turned the a/c off and that went away, turned the a/c back on and the screaching started again, turned it back off and once I started driving turned my a/c back on and It didn't make that noise, it was the first time it's done that, so this is a new thing I'll be looking out for. Perhaps a loose pulley, er so I hope.


Thanks!
Jessica

OldTires

Honestly, at the rate you are going spending on parts and time and aggravation, you should take it to an experienced mechanic or the dealer. In the long run, it will be cheaper for them to fix and guarantee their work.

Also, expect to be spending more money on just about everything. On my 96, just in the past 3 years, I have changed front and rear suspensions, AC system, exhaust system, distributor, alternator and battery, radiator, water pump, and a bunch of sensors. At 21 years old, the components are reaching end of life, so expect other things to go bad.

The AC squealing could be a loose belt, or the compressor going bad, putting excessive drag on the belt and making it slip. Eventually it could lock up and throw the belt off.

GreaseMonkey17

Pull the belt and make sure your a/c compressor clutch isn't locking up . That would most certainly stall the engine at a stop . I have another thought but I'll wait to see the results of checking for the compressor or any other pulleys to be locking up with belt removed .