No engine braking?

Jeepjeepster · **Posted:** Thu Jan 19, 2006 9:31 pm

Has anyone ever noticed the engine braking on the libby really sucks? I was going down a really, REALLY steep hill today so i slowed down to about 15mph and put it into 1st. The engine went all the way up to 3k rpms's so i had to hit the brakes. Kinda stupid i think, our Grand cherokee doesnt do that. it should keep me at a low speed without the engine soring up into through rpms.

USAFCOP · **Posted:** Thu Jan 19, 2006 10:14 pm

I think it depends on your tranny. I have heard many people with the 42 RLE complain about this.

I have the old 45 RFE, and mine has great compression braking ability, but for some reason, she does not like to get up the mountain very fast w/o the rpms jumping. So I guess both trannys have their pro's and con's

jpzkj · **Posted:** Thu Jan 19, 2006 10:24 pm

Yep....the 42 RLE sucks for going down steep hills.

I went down a long STEEP hill and it got all the way up to 500 RPM on the Tach before I used the brakes.....Another Club members '02 with the 45 trans. never went over 2500 RPM on the same hill.

Jeepjeepster · **Posted:** Thu Jan 19, 2006 11:50 pm

jpzkj wrote:

Yep....the 42 RLE sucks for going down steep hills.

I went down a long STEEP hill and it got all the way up to 500 RPM on the Tach before I used the brakes.....Another Club members '02 with the 45 trans. never went over 2500 RPM on the same hill.

500rpm? Did you mean 5000rpm. I dont see how you let it get that high. I was flying and i was only up to 3k. When im in 4low it does ok, not as good as it should. Its never gotten it over 3k in 4low, and i go down some pretty steep hills.

Edvalencia · **Posted:** Fri Jan 20, 2006 12:51 am

USAFCOP wrote:

I think it depends on your tranny. I have heard many people with the 42 RLE complain about this.

I have the old 45 RFE, and mine has great compression braking ability, but for some reason, she does not like to get up the mountain very fast w/o the rpms jumping. So I guess both trannys have their pro's and con's

Exactly the same goes for me. I have an '02 with the 45 RFE. Going down hills, especially in 4Lo I get great engine compression. On my way to Moab, however, I almost redlined it twice trying to get up some of the hills on the highway. One gal driving a 4 Cyl econobox passed me while going up one of the hills :oops:

I'm sure the larger tires have alot to do with it. (at least that's what I tell myself.)

Ed

Myke · **Posted:** Fri Jan 20, 2006 1:38 am

I have an 02 w/ the 45 and it's decent for coming down a hill (could be better) but going up a hill it needs 4 lo

QuietOutdoorsman · **Posted:** Fri Jan 20, 2006 2:17 am

In my '04, 3.7L and the NSG370 5-spd, in 1st gear 15 mph is turning near 3k rpm.

jpzkj · **Posted:** Fri Jan 20, 2006 2:36 am

Jeepjeepster wrote:

jpzkj wrote:

Yep....the 42 RLE sucks for going down steep hills.

I went down a long STEEP hill and it got all the way up to 500 RPM on the Tach before I used the brakes.....Another Club members '02 with the 45 trans. never went over 2500 RPM on the same hill.

500rpm? Did you mean 5000rpm. I dont see how you let it get that high. I was flying and i was only up to 3k. When im in 4low it does ok, not as good as it should. Its never gotten it over 3k in 4low, and i go down some pretty steep hills.

5000k Rpm yes...

It was at Camp Jeep in CA....a long and steep hill in 4LO. What is steep to some...might not be steep to others. The bottom line is that the 42 Trans. allows much less compression braking than the 45 does...(this is a long time known issue)

I've never been in or driven a manual trans. KJ so I can't tell ya how that one compares. In comparision to other Jeeps I have and other 4x4's i've owned...its really not up to the task of long steep decents without riding the brakes.

Straight6Jeff · **Posted:** Fri Jan 20, 2006 9:01 am

The poor compression braking is due to lack of torque converter lock up. You can wire in a switch to force lock up and comp braking, but other areas in the trans need to be addressed before doing this to prevent failures.

Straight6Jeff · **Posted:** Fri Jan 20, 2006 9:05 am

http://www.turbodieselregister.com/foru ... ery+switch

http://www.turbodieselregister.com/foru ... ery+switch

http://www.turbodieselregister.com/foru ... ery+switch

brpn#1 · **Posted:** Fri Jan 20, 2006 10:26 am

i live in the NC mtns.. and when im on the way downhill.. i can put it in l2 and take off the overdrive.. it does pretty good keeping me at whatever speed im at.. but going uphill is a diff story.. blah.. downshift.. bog.. downshift.. bog.. gd i hate that crap

sleeve84028 · **Posted:** Fri Jan 20, 2006 10:47 am

Downshifting going up hill is due to lack of Horsepower to keep the Liberty moving at any given constant speed. The 3.7L engine is great, but the Liberty is HEAVY! Torque is good for getting moving and accelerating (changing speed.)

My 02 has great engine braking chacteristics just like noted above.

Jeepjeepster · **Posted:** Fri Jan 20, 2006 12:59 pm

My jeep does great going up hills. I dont know what thats all about, hit the little button to keep it in 3rd, takes care of that for me. Even does good pulling the boat on hills.

Eddo · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 1214

I know this sound silly, someone correct me if I am wrong.

If you have no compression braking and the engine is revving up to 5000rpms, then it wouldn't be a problem with the transmission. Something with the engine. Maybe different engine programing or something different in the engine when they changed transmissions.

Since the transmission connects the engine to the drive train, it is doing its job of spinning up the engine if it goes up to 5000rpms. Just engine is just not providing enough resistance to slow it down. If the engine just sat at 2000rpms and the jeep took off then that I would think would be a transmission problem since it is not spinning up the engine.

Jeepjeepster · **Posted:** Fri Jan 20, 2006 5:54 pm

Thats what i was thinking eddo. I just didnt want to say it.

bennybmn · **Posted:** Fri Jan 20, 2006 7:52 pm

All the more reason for a manual tranny...

jpzkj · **Posted:** Sat Jan 21, 2006 1:07 am

Nope.. it's a transmission thing ..if it wasn't there wouldn't be a difference between years of KJ...they all have the same motor.

It's about the torque convertor and the gearing. There is no swapping the old trans. into the new KJ...or..no computer flash...no computer change. There have been discussions about this with the Jeep Eng's. (not by me..but related to me by those persons that have had the conversations).

Just have to use your brakes more with the later model trans. Maybe the Lock-up convertor in the link above ...I don't know about that.

I'm just going to use the brakes and call it a day.

Eddo · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 1214

Just wondering if it was the tranny and gearing, then why does the engine go up to 5000rpms?? Just doesnt make sense, unless someone can actually explain it better. Seems to me that the transmission IS doing it's job of spinning up the engine, the engine is just not providing enough resistance. Unless the RPMs are not measure directly off the engine, and instead somewhere on the transmission. But then you could probably tell, because the engine wouldn't be screaming either.

For example, put your Jeep in neutral and there is no compression braking at all, but your engine still sits at idle RPMs. If it was the transmission you would think the engine would not spin up to such a high RPM. If the torque converter was not providing enough coupling or locking up then you wouldn't have high RPMs.

Also, I've driven 42RLE when hooked up to the 4.0 and that seems to have plenty of compression braking. I know different animal, but still the tranny is still probably almost the same.

Jeepjeepster · **Posted:** Sat Jan 21, 2006 1:35 pm

Eddo, now that i think about it, ive been in a 00 grand with the 4.0 and the 42rle tranny(if thats what they use in them), and it did the same thing. I still do not believe the tranny has anything to do with this. If it was the tranny, then the engine should stay at whatever rpm's it wants while the torque spins up heating up the tranny oil. The 1st gear ratio in the 45 and 42 tranny is the same. The tcase is the same, but the torque is not. I think thats all thats hurting it is the torque and something to do with the engine.

Eddo · **Joined:** Thu Jul 07, 2005 7:01 pm **Posts:** 1214

Jeepjeepster wrote:

Eddo, now that i think about it, ive been in a 00 grand with the 4.0 and the 42rle tranny(if thats what they use in them), and it did the same thing. I still do not believe the tranny has anything to do with this. If it was the tranny, then the engine should stay at whatever rpm's it wants while the torque spins up heating up the tranny oil. The 1st gear ratio in the 45 and 42 tranny is the same. The tcase is the same, but the torque is not. I think thats all thats hurting it is the torque and something to do with the engine.

Yeah you are probably right. I'm sure it is something with the tranny, but just dosen't make much sence to me yet.

No engine braking?

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