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Can you help me with transmission diagnosis?  RSS feed
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linewarbr
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Joined: 17/07/2009 12:13:13
Messages: 19
Location: Baton Rouge, LA
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Hey, hoping for a little help from you guys that have torn these little beasts apart and put them back together. I've been experiencing some transmission weirdness, and I think I may know what the problem is but I want to see if you guys can chime in.

I made this first post on LOSTJeeps on 2/9/10:

I was in the drive-thru at McDonalds, with the Jeep in gear and my foot on the brake. Jeep was not yet up to operating temperature, temp gauge was about 1/5 up. As I let off the brake I heard/ felt a pop, and the Jeep seemed to not want to accelerate as normal, like it took a lot more pedal to make it go.

I immediately shifted into neutral, and only shifted to drive when I needed to pull forward to the pick-up window. No CEL at this point. I idle it over to a parking spot, put it in park and set the e-brake and turn it off. First I look closely for fluid leaks both under the Jeep, and in the drive-thru lane, (love having a diesel at this point, because you KNOW diesel oil when you see it on the ground - and trans fluid is red) and see nothing - skid plates are both dry. Open the hood, and the trans dipstick is sticking out about 2 inches.

I push the dipstick back in, go back in the Jeep and hook up my code scanner to find "P0841 Trans Fluid Pressure Switch." I clear the code, start the Jeep back up, and it drives normal back to my office .36 miles away.

I'm thinking that the pop I heard was the trans dipstick hitting the underside of the hood, but I'm unsure what would cause this - maybe a clogged breather? Last week I checked the fluid and it seemed slightly on the low side, so I added ~1/4 quart of fluid, not a whole lot. It is colder today than it has been, but not yet cold enough to fire up the viscous heater. (Correction, I think the VH may have been operating)


Then, I updated the thread with this today 3/1/10:

So, it happened again today but this time the engine stalled and quit. I was in the drive-thru of a restaurant, not up to operating temp yet, idling in gear, and I noticed that when I let off the brake, it didn't feel as "ready-to-go" as usual. I get my food and pull out (luckily not on to a busy street) and when I let off the accelerator for the upcoming stop sign, it starts bucking and then stalls out - it startled me, I thought it was going to explode or something. Opened the hood, trans dipstick was still in place. Checked it with my scanner, no codes. After a few minutes I crossed my fingers and tried starting her - started right up, no problems. Didn't stall when I shifted back into Drive - she acted like nothing happened.

I have just over 69k miles, 45k of those are mine. I know the fluid level is now correct after the above posts. This only seems to happen under these conditions - not up to operating temp, extended time of idling in gear.

Any ideas of anything I can do to better diagnose what is causing this?


The thread on LOST is here: http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=50040


In this war of lines, so many have been crossed. Where will it all stop?

*SOLD* 2006 Jeep Green CRD Sport
Build Date 12/2005
EHM, V6 Airbox, Fumoto, Samcos, Green Diesel Engineering Tune
245/70/16 Destination A/T's

2007 WK CRD Limited, stock AFAIK
GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 371
Location: Southeast Michigan
It could be that your torque converter is starting to go. The transmission is going into "limp-in" mode and staying in 3rd unlock, this makes it difficult to accelerate. After the shutdown the controller will reset and then everything works normal...for a while. There could also be a loose wiring connection that is making the trans flake out, but this is rare.
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linewarbr
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Joined: 17/07/2009 12:13:13
Messages: 19
Location: Baton Rouge, LA
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If I am going to replace the TC, should I go ahead and replace the pump as well?

Also, I guess if a new TC is in my future, then upgrading to the HOT tune is too. . .

In this war of lines, so many have been crossed. Where will it all stop?

*SOLD* 2006 Jeep Green CRD Sport
Build Date 12/2005
EHM, V6 Airbox, Fumoto, Samcos, Green Diesel Engineering Tune
245/70/16 Destination A/T's

2007 WK CRD Limited, stock AFAIK
linewarbr
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Joined: 17/07/2009 12:13:13
Messages: 19
Location: Baton Rouge, LA
Offline
I need to add another symptom: In normal driving, after I come to a complete stop then let off the brake to start accelerating again, there is a clunk in the drivetrain somewhere. I feel it more than hear it. It is more pronounced if I have to stop suddenly, then immediately let my foot off the brake after coming to a complete stop. Is this maybe the springs in my TC bottoming out? I have never noticed "shudder" before.

I appreciate you guys making yourselves available to us to ask you questions, I know you don't have to do this.

In this war of lines, so many have been crossed. Where will it all stop?

*SOLD* 2006 Jeep Green CRD Sport
Build Date 12/2005
EHM, V6 Airbox, Fumoto, Samcos, Green Diesel Engineering Tune
245/70/16 Destination A/T's

2007 WK CRD Limited, stock AFAIK
GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 371
Location: Southeast Michigan
When you are coming to a stop the trans should be unlocked so the springs are not engaged, unless the trans is staying in lock-up for some reason. When you are braking and slowing down from 20 to 0, is the engine rpm always at idle or at what speed does it reach idle? If the trans pump is losing prime it will feel as if the vehicle is not in gear and then it may come back once the pump is working again. We are not experts in the trans, but with your symptoms a TC pump might be worthwhile. There is also a check valve the could be failing. Keep us posted.
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linewarbr
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Joined: 17/07/2009 12:13:13
Messages: 19
Location: Baton Rouge, LA
Offline
Thanks for the help. Talked with a guy at Aamco who thinks it could be something as simple as the anti-drainback valve in my spin-on malfunctioning. Since this only occasional, I'm going to keep going with it until you guys can offer a 6-speed manual conversion. . . .

Seriously though. . . do you guys think you will ever be able to offer a manual-tranny conversion kit?

In this war of lines, so many have been crossed. Where will it all stop?

*SOLD* 2006 Jeep Green CRD Sport
Build Date 12/2005
EHM, V6 Airbox, Fumoto, Samcos, Green Diesel Engineering Tune
245/70/16 Destination A/T's

2007 WK CRD Limited, stock AFAIK
 
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