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Unread 03-19-2014, 04:07 PM   #1
Colo.kid
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2014 with 5.7 has little engine compression wheel'n

Thanks in advance for any thoughts.

We are avid wheelers that occasionally do usually tough trails, especially for a relatively stock (except for OS tires) 2014 Overland. Unlike our previous 2014 with the V6, this rig has no engine compression going downhill--even in 1st gear.
It holds momentarily and then releases. We had the same issue with a 2005 WK with the Hemi and were told by Jeep engineers at that time that it was a computer programming issue (the high vacuum cutoff, supposedly to protect their "new" hemi). They said the level had been increased and problem resolved. Apparently not true. And it is not an issue with our 2008 model with the CRD.

Has anyone else experienced this issue, which is a safety issue if one does some serious, steep wheeling. Sure the downhill assist control can be used, but that is suppose to supplement engine braking and since it is all brake dependent it is not reliable, not to mention it is a PITA on the trail.

Thoughts please.

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Unread 03-19-2014, 06:03 PM   #2
TurboRush
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Did you try using hill decent control?
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Unread 03-19-2014, 06:28 PM   #3
Colo.kid
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I may not have made it clear that hill descent "works" but it is based application of the brakes and is therefore unreliable if you are a serious off roader. And it is an obnoxiously loud and jerky experience, There was a time when Jeep was noted for their "lockup" transmission. Is this the problem--the transmission for the hemi application does not for some reason lockup the same as for the V6 application?
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Unread 03-19-2014, 06:55 PM   #4
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They must have changed something for 2014. My 2011 V8 has some engine braking and hill decent control operates smoothly. I'm not doing unusually tough trails, however, i.e. those that have some risk of bending metal. For 2014 both the V8 and V6 use the same basic transmission, but they could be programmed differently.
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Unread 03-20-2014, 08:54 AM   #5
tjkj2002
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Quote:
Originally Posted by Colo.kid View Post
Thanks in advance for any thoughts.

We are avid wheelers that occasionally do usually tough trails, especially for a relatively stock (except for OS tires) 2014 Overland. Unlike our previous 2014 with the V6, this rig has no engine compression going downhill--even in 1st gear.
It holds momentarily and then releases. We had the same issue with a 2005 WK with the Hemi and were told by Jeep engineers at that time that it was a computer programming issue (the high vacuum cutoff, supposedly to protect their "new" hemi). They said the level had been increased and problem resolved. Apparently not true. And it is not an issue with our 2008 model with the CRD.

Has anyone else experienced this issue, which is a safety issue if one does some serious, steep wheeling. Sure the downhill assist control can be used, but that is suppose to supplement engine braking and since it is all brake dependent it is not reliable, not to mention it is a PITA on the trail.

Thoughts please.
Are you in 4low? If so it's your gear ratio that is killing your compression braking with those bigger tires.

Sure I know not the same but my KJ's downhill compression braking sucked before I really lowered my gear ratio and not just in the diffs.With 5.13 gears,35" tires,and 4.3:1 low in the t-case I have to give it gas to go down steep hills now otherwise my KJ will actually stop itself without using the brakes.
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Unread 03-20-2014, 10:40 AM   #6
ColdCase
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By chance were you in D instead of 1? I double checked today, but left it in D the first time and about 3mph it shifted from 1 to 2 and lost the brake effect. Otherwise seemed to retain compression braking whatever there was.
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Unread 03-20-2014, 10:42 AM   #7
ColdCase
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Quote:
Originally Posted by tjkj2002 View Post
Are you in 4low? If so it's your gear ratio that is killing your compression braking with those bigger tires.

Sure I know not the same but my KJ's downhill compression braking sucked before I really lowered my gear ratio and not just in the diffs.With 5.13 gears,35" tires,and 4.3:1 low in the t-case I have to give it gas to go down steep hills now otherwise my KJ will actually stop itself without using the brakes.
The Op was questioning why the the 2014 V8 was feeling different than the 2014 V6... not compression braking or gear ratios or tires in general. He seems to know what he's doing.
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Unread 03-20-2014, 11:52 AM   #8
tjkj2002
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Quote:
Originally Posted by ColdCase View Post
The Op was questioning why the the 2014 V8 was feeling different than the 2014 V6... not compression braking or gear ratios or tires in general. He seems to know what he's doing.
He's talking about compression braking and both gear ratio and tire size have direct effect on.There also will be a drastic difference between a gas V6 and gas V8,the V8 should have way more if tires and gear ratio are the same between the 2 vehicles.
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Unread 03-20-2014, 12:18 PM   #9
ColdCase
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Quote:
Originally Posted by tjkj2002 View Post
He's talking about compression braking and both gear ratio and tire size have direct effect on.There also will be a drastic difference between a gas V6 and gas V8,the V8 should have way more if tires and gear ratio are the same between the 2 vehicles.
I think it is simpler than that. His 2005 WK hemi provided compression braking for a few seconds then seemed to free wheel. His 2014 V8 seems to do the same thing and he was wondering if that was the way it is.

He was not asking the amount of compression braking and the theory, he was asking why his 2014 V8 compression brakes for a few seconds then free wheels... as he was told Jeep fixed it awhile ago.

He mentioned his 2014 V6 and 2008 CDR did not have this "free wheel" characteristic.
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Unread 03-20-2014, 04:04 PM   #10
Colo.kid
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Quote:
Originally Posted by tjkj2002 View Post
Are you in 4low? If so it's your gear ratio that is killing your compression braking with those bigger tires.

Sure I know not the same but my KJ's downhill compression braking sucked before I really lowered my gear ratio and not just in the diffs.With 5.13 gears,35" tires,and 4.3:1 low in the t-case I have to give it gas to go down steep hills now otherwise my KJ will actually stop itself without using the brakes.
Yes, I am definitely in low range, first gear. As for the bigger tires they are size 275/55, which is not enough of a size change to effect the transmission ratios or in this case the downhill compression. I am taking it in to the Jeep dealership to check if the lockup torque converter is operating correctly since it appears mine is a unique occurence.

Thanks for the responses.

BTW I see I need to update my profile so folks know what I do and do not have.
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Unread 03-22-2014, 07:29 PM   #11
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I noticed the same in my 14 Diesel. I apparently don't know how to use the hill descent control either because all it did was blink at me
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Unread 03-22-2014, 09:42 PM   #12
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Quote:
Originally Posted by goodburbon
I noticed the same in my 14 Diesel. I apparently don't know how to use the hill descent control either because all it did was blink at me
After it blinked did the light stay on or turn off?

HDC along with Rock and 4 lo cannot be shifted while in drive. The EVIC should instruct you on how to do it but going into N slower than 3mph then choosing the desired setting then back to D will get it done.

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Unread 03-23-2014, 07:35 PM   #13
goodburbon
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Blinked and stayed off. So I tried it again, but this time before putting it in gear blinked and stayed off again. The display Said that to switch to 4 lo put transmission in N. I didn't want 4 lo, just compression braking going down a friends driveway, the ford explorer does it in hi, the jeep is twice the vehicle and doesn't?
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Unread 03-23-2014, 07:48 PM   #14
Jackal01
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Quote:
Originally Posted by goodburbon View Post
Blinked and stayed off. So I tried it again, but this time before putting it in gear blinked and stayed off again. The display Said that to switch to 4 lo put transmission in N. I didn't want 4 lo, just compression braking going down a friends driveway, the ford explorer does it in hi, the jeep is twice the vehicle and doesn't?
I believe HDC only works in 4Low. Mine is that way. It would be nice if it worked in 4High.
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