Unstable/Shut Down when coming to a complete stop

[alexmolinavr6]

Hi, I’m having a problem with my 02 KJ 4x2, I hope someone can help me.

Yesterday, when on my way back from work, I experienced something that has never happened to me before, when I was approaching a light/intersection and needed to come to a complete stop, My KJ felt like when you are driving a car with standard transmission, braking but without pushing your clutch in, the feeling that shakes and almost shuts off.
On most of the stops, it came stable after a little, but it did actually shut off a few times. When it did not shut off, I felt like the transmission was not shifting down as fast as it should have.

Today, I noticed my temp gauge ¾ of the way up (it had never gone that high before) my radiator is good, since it was replaced recently, I don’t know it the problem might be related.

Another factor from yesterday and today is that it rained kind of hard; it has rained like that several times before since I’ve owned this KJ. I was thinking that may be a sensor got wet.

However, I have run out of ideas.

I hope someone might be able to help me.

Thanks in advance,

alex

 

[Uncle Krusty]

The best place to start these days is by pulling the error codes.

After that, my first suggestion is to clean the battery terminals, and check the battery and charging system. As much of the engine/transmission is now computer controlled, I've found that poor electrical conections tend to bring on the gremlins... I had a Grand Cherokee that would sometimes forget where idle was, and stall when coming to a stop. Cleaning the terminals and a couple trips around the block and the computer would re-set and idle propperly.

If the problem is in the transmission, the overheating could be just another symptom. Remeber, a good portion of the heat generated in an automatic transmision is dissapated through the radiator. Most radiators now days are made to handle only the heat generated by a properly running engine & transmission, and not much more.

There are a couple problems in the engine that could make it run hot as well. To lean of mixture or incorrect timiming are just a couple.

Hope you can get it sorted out soon, without much $$$ spent.

 

[LibertyTC]

3/4 of the way on temp gauge...that is hot. Is the electric fan running?
When was the last time or how many miles since you last serviced the transmission by dealer? How many miles on your 02 kJ? Has the thermostat or water pump been replaced?
Next time it does the shudder while slowing down, note your rpm is it remaining high as you slow or is it at 1000rpm etc and 700 at idle for instance?

 

[valvestem]

My guess is that the trans has a bad/going bad kickdown solenoid. The one that senses vehicle speed and kicks the gears down while coming to a stop.

 

[AlexKJ]

Start pulling any error code you have...

My guess is that the temperature issue and transmission behavior are unrelated. If you changed the radiator recently, you maybe have an air bubble somewhere...

As for the transmission's behavior, try to look carefully when is happening and see the rpms... see if the transmission doesn't downshift b/c the rpm are too high (the engine is self throttling)... when it happen again, move the shifter to N and coast... see if the rpms drops ~600 or not.

If the rpms drops to 600 it's a transmission related problem... if the rpms rises to 1000 (or more) you have an engine problem.

Good luck!

 

[alexmolinavr6]

The best place to start these days is by pulling the error codes.

After that, my first suggestion is to clean the battery terminals, and check the battery and charging system. As much of the engine/transmission is now computer controlled, I've found that poor electrical conections tend to bring on the gremlins... I had a Grand Cherokee that would sometimes forget where idle was, and stall when coming to a stop. Cleaning the terminals and a couple trips around the block and the computer would re-set and idle propperly.

3/4 of the way on temp gauge...that is hot. Is the electric fan running?
When was the last time or how many miles since you last serviced the transmission by dealer? How many miles on your 02 kJ? Has the thermostat or water pump been replaced?
Next time it does the shudder while slowing down, note your rpm is it remaining high as you slow or is it at 1000rpm etc and 700 at idle for instance?

Start pulling any error code you have...

My guess is that the temperature issue and transmission behavior are unrelated. If you changed the radiator recently, you maybe have an air bubble somewhere...

As for the transmission's behavior, try to look carefully when is happening and see the rpms... see if the transmission doesn't downshift b/c the rpm are too high (the engine is self throttling)... when it happen again, move the shifter to N and coast... see if the rpms drops ~600 or not.

If the rpms drops to 600 it's a transmission related problem... if the rpms rises to 1000 (or more) you have an engine problem.

Good luck!

I know that the first thing I should’ve done was to check the codes, I have no lights on. My AutoZone stops checking codes at 9pm, that’s why I didn’t have my computer scanned, I will though.

I’m running on 245/70/16 Hankock AT (nothing out of the ordinary). My speedo yes quite accurate, since the radar that sometimes the cops place on the street reads what my speed is when I’m driving thru.
My KJ has 138xxxmiles

My radiator wasn’t exactly replaces, it was just fixed (the bottles were coming apart from the radiator) but that was back on the 1st week of April 2010.

The other factor that came to my mind is that the 1st day it started acting up (3 days ago, Aug 30, 2010) I went through an empty non-paved road (about 50 yards long total). But again the lot is almost flat dirt and grass.

Yesterday, I wasn’t able to check if my fan was running, since it was late at night and I had to drop my KJ at my parent’s house and use 1 of their cars before my problem gets more expensive.

Although my transmission problem started on Aug 30, the temp problem did not came up until last night (Aug 31st).

My gears shift properly all the time. The only problem is when coming to a complete stop.

If I switch my gear to neutral, my rpms come back up to ~1000rpm.

I haven’t serviced my KJ at the dealer since I have owned it (end of march 2010).
I always do all the maintenance my self. I just changed my engine oil last week (synthetic), ****** oil is on the right level.

One more thing, since I got my KJ, my battery light goes on and off sometimes when driving, however, I checked my voltage, and it shows a normal reading.

I have never replaced the water pump or thermostat.

 

[ptsb5a]

Check for an EVAP leak. When I rerouted my winch power cables I removed the Purge Solenoid to pass the uber thick wire under it. When I put it back in I forgot to hook up the hoses. It took two days of running like crap before it popped a code (p0440) and face-palmed me. With a huge leak you'll get crappy idle, lean conditions and stumbling while decellerating.

My .02 but might be worth investigating.

 

[AlexKJ]

If I switch my gear to neutral, my rpms come back up to ~1000rpm.

Your engine is self-throttling, that why the transmission doesn't downshift properly... could be several things: poor electrical connection to the battery, bad alternator, bad IAC Motor, bad plugs, bad fuel pump... Anything that could be telling to the ECM that inject more fuel to prevent that the engine die on you...

Mine did the same until I change the IAC Motor... then the problem never came back... but for you it could be something else...

Good luck

 

[LibertyTC]

Battery light- Get the battery load tested. If it fails replace it.
Both the charging system and Transmission codes can only be pulled by dealers.
High Idle- IAC effects idle and throttle body ports needs cleaning. Intake air control can really mess with and cause sticking coming down to idle. Carbon builds up in ports as well as the IAC plunger and my rpm problem was cured by 20 minutes of cleaning after removing Torx screws on the IAC attached to the throttle body. It is on the drivers side, lower unit with electrical connection. (top unit is TPS)
USe Spray throttle body cleaner get the IAC clean and dry with compressed air and get spray into the port once IAC is off. Then remove air intake hose and clean the throttle body intake as well. This may greatly help the sticky idle problem coming down to a stop. In my situation, I also got a ****** shudder and rpm was remaining at 1200 and was greatly feeling like I was being pushed forward while braking.
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Note there should be a fair amount of resistance in pushing down on IAC Plunger.
If It is pushed down easily (spring has weakened) Replace the IAC.