2012 JGC Ltd 3.6L - Thump/Bump/Shudder on acceleration - Jeep Garage - Jeep Forum

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Old 09-01-2016, 08:50 PM
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2012 JGC Ltd 3.6L - Thump/Bump/Shudder on acceleration

Hi folks! I am back again with another issue. Actually, I have been living with the issue for the better part of two years, and lately it just seems getting worse. I have around 85K on my JGC. In the last year, I have brought it to a dealership for recalls and asked them to make sure the software was up to date. It is....

Accelerating from a level stop, you can feel a distinct thump-thump (shudder, bump, fishbite, etc.) seemingly coming from the rear end. The transfer case is in AUTO, and tranny is in D. The thumps happen almost every time the JGC is in this situation (which is at every stop sign and light). The thumps happen between 1000-1500 RPM.

I have had NO codes to speak of and the transmission seems to be shifting normally. Gas mileage is normal, and I have been using 87 octane all along. It does not feel like the engine is missing or somehow cutting out.

I have gone through all TSB's relevant to my vehicle. I do not see anything which addresses my issue.

Trying to narrow down the issue, I have done the following:

1. Putting the tranny in "1", and the transfer case in "SPORT". Theoretically, this should limit the issue to the transmission, propeller shaft, and rear differential. - Problem still happens and is repeatable. Its not a shifting issue as the transmission is forced to stay in 1st...but could be a torque converter lockup issue. The transfer case should not be contributing as the SPORT mode forces the torque to be primarily directed to the rear differential. I do not have a limited slip rear differential.

2. I have disconnected the battery and allowed the vehicle to sit about 1 hour before reconnecting. The idea here was to force the transmission back into 'learn mode' again to see if there was any improvement. - Problem seemed to have gone away for about 2 days, then returned.

3. I convinced myself it had to have been one of the CV joints going bad in the two piece rear propeller shaft or the CV joints in the front driveshaft. I replaced both today, only to have the problem STILL THERE! Arrrgh..

I am now wondering if its a sticky valve body causing issues. I am ready to order and install a new valve-body (R2108213AC) & filter, however, if that's not going to fix it, I don't feel like taking a ATF+4 bath..

I also wonder if this is really a torque converter/transmission clutch issue. If so, I would sooner sell this vehicle and never come back to Jeep...

Any thoughts, suggestions, etc...? Thanks!

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Old 09-05-2016, 07:28 PM
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Quote:
Originally Posted by LJSMITH1 View Post
Hi folks! I am back again with another issue. Actually, I have been living with the issue for the better part of two years, and lately it just seems getting worse. I have around 85K on my JGC. In the last year, I have brought it to a dealership for recalls and asked them to make sure the software was up to date. It is....

Accelerating from a level stop, you can feel a distinct thump-thump (shudder, bump, fishbite, etc.) seemingly coming from the rear end. The transfer case is in AUTO, and tranny is in D. The thumps happen almost every time the JGC is in this situation (which is at every stop sign and light). The thumps happen between 1000-1500 RPM.

I have had NO codes to speak of and the transmission seems to be shifting normally. Gas mileage is normal, and I have been using 87 octane all along. It does not feel like the engine is missing or somehow cutting out.

I have gone through all TSB's relevant to my vehicle. I do not see anything which addresses my issue.

Trying to narrow down the issue, I have done the following:

1. Putting the tranny in "1", and the transfer case in "SPORT". Theoretically, this should limit the issue to the transmission, propeller shaft, and rear differential. - Problem still happens and is repeatable. Its not a shifting issue as the transmission is forced to stay in 1st...but could be a torque converter lockup issue. The transfer case should not be contributing as the SPORT mode forces the torque to be primarily directed to the rear differential. I do not have a limited slip rear differential.

2. I have disconnected the battery and allowed the vehicle to sit about 1 hour before reconnecting. The idea here was to force the transmission back into 'learn mode' again to see if there was any improvement. - Problem seemed to have gone away for about 2 days, then returned.

3. I convinced myself it had to have been one of the CV joints going bad in the two piece rear propeller shaft or the CV joints in the front driveshaft. I replaced both today, only to have the problem STILL THERE! Arrrgh..

I am now wondering if its a sticky valve body causing issues. I am ready to order and install a new valve-body (R2108213AC) & filter, however, if that's not going to fix it, I don't feel like taking a ATF+4 bath..

I also wonder if this is really a torque converter/transmission clutch issue. If so, I would sooner sell this vehicle and never come back to Jeep...

Any thoughts, suggestions, etc...? Thanks!
Hey, I'm new to the Jeep world and have had the the same symptoms with my rececently purchased '05 JGC LTD 5.7L from day one. I didn't read the owners manual which stated I shouldn't use fuel lower than 89 octane. I was being cheap one day, filled it with a low octane fuel and coincidentally on that same day, the crankshaft position sensor threw an error code. It's a $30 part. Fairly easy to replace and since I replaced it, the vehicle's been running like a dream.
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Old 09-05-2016, 07:57 PM
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Re: 2012 JGC Ltd 3.6L - Thump/Bump/Shudder on acceleration

Quote:
Originally Posted by JanMan View Post
Hey, I'm new to the Jeep world and have had the the same symptoms with my rececently purchased '05 JGC LTD 5.7L from day one. I didn't read the owners manual which stated I shouldn't use fuel lower than 89 octane. I was being cheap one day, filled it with a low octane fuel and coincidentally on that same day, the crankshaft position sensor threw an error code. It's a $30 part. Fairly easy to replace and since I replaced it, the vehicle's been running like a dream.
Thanks, but I have the 3.6L, and have no error codes. The engine itself is running with no missing or knocking.
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Old 10-13-2016, 03:39 PM
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Re: 2012 JGC Ltd 3.6L - Thump/Bump/Shudder on acceleration

UPDATE -

So, since my last writing about this issue, I have replaced front and rear prop shafts with no improvements.... It was a cheap longshot, and I was hoping that it would fix it.

A couple of weeks ago, I broke down and purchased a Chrysler re-manufactured valve body (R2108213AC), a new filter, pan (original looked like it was going to perforate from rust) & gasket. Installed, and refilled transmission (I have the special dipstick and oil level chart). Took it out for test drive and all seemed fine for a few miles....

NOPE!
Bowling ball in trunk again! The only thing left it could be is either the torque converter, and/or transmission oil pump/torque converter circuit.

So, I decided to keep driving it until something further 'happened', because the alternative is likely a much bigger fix $$$. Well, while I was driving this past weekend from Boston to VT at highway speeds, the check engine light comes on...WTF?!? Nothing noticeable with the running of the Jeep, everything seemed ok. I just rolled over 87,000 miles and the Jeep was running fine.

I was able to pull off, and find an Advance Auto Parts store nearby. I plugged in a code reader and "P0741" came up. Guess what that is? "Torque Converter Clutch Performance"... Ugh..

However, driving back to CT from VT later that weekend the MIL miraculously cleared . I wish my problem did. I still feel the bowling ball in the trunk every time I accelerate from a stop (like in traffic).

To be sure, tonight I am going to recheck the oil level <again>. Most of the 7L of fluid was changed when I replaced the valve body, so I am fairly certain dirty fluid is not the issue. Also, the reconditioned valve body has the lockup solenoid on it, and so I have to assume its fine. I have 88K miles on this Jeep and this kind of stuff should NOT be happening.

Anyone have any ideas or similar experience? I called my local Jeep dealer on Monday, who promised to call me back to schedule...3 days later, no call back yet...and I can assume they don't really want the job. I am almost ready to get rid of this Jeep and go to a Ford Explorer... I am not happy with how the build reliability with Chrysler has deteriorated over my many Chrysler vehicles ('94 Intrepid, '98 Intrepid, '02 Durango, '04 Grand Caravan, '06 Jeep GRC, and now my '12 Jeep GRC). Between this stuff and the 5+ Mfr recalls, I am about done with Fiat/Chrysler products..
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Old 10-16-2016, 08:21 PM
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Re: 2012 JGC Ltd 3.6L - Thump/Bump/Shudder on acceleration

The transmission learns driving style and shift points. Go into a shop and have your transmission flashed


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Old 10-24-2016, 03:28 PM
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Re: 2012 JGC Ltd 3.6L - Thump/Bump/Shudder on acceleration

Quote:
Originally Posted by JeepinTim View Post
The transmission learns driving style and shift points. Go into a shop and have your transmission flashed
Sent from my iPhone using JeepGarage

Transmission was flashed at the very beginning of the issue. No change.

The 'learn' program can be re-initiated after leaving the battery disconnected for at least 30 min. I also did this and had no improvements.

I am pretty sure this is a torque converter/transmission issue.
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