Power Transfer
While wheeling recently I noticed something iffy in the sense that I do not know if this is the right behavior or not and I can't seem to find an answer in google.
Basically, when the jeep is in HI on the transfer case and there is high load on the vehicle (e.g recovery of other vehicle or deep and steep sand hill) the engine would rev up to about 2k RPM even if gas pedal is floored, but there is no wheel movement. This happens in 1-2 gear, in 3 and in D. If I switch it to LO, then it starts to go. On HWY, the engine revs past 2k RPM without issue. Is this behavior normal? |
Sounds like you are getting enough traction to over-whelm the torque/power you have in high. You need less traction!, (or more power). Just a thought.
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Originally Posted by DFlintstone
(Post 1201058)
Sounds like you are getting enough traction to over-whelm the torque/power you have in high. You need less traction!, (or more power). Just a thought.
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If someone in stuck up to their body line in mud... pulling them out in 4 hi is a hell of a lot to ask of a vehicle.
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The High and Low refers to the gear not the load.
4 hi should be used on trails and loose surface conditions in which you are going forward at any sort of speed. 4 lo is used for crawling up or down hills, pulling and any situation where you need maximum traction and torque. |
Originally Posted by razor02097
(Post 1201388)
The High and Low refers to the gear not the load.
4 hi should be used on trails and loose surface conditions in which you are going forward at any sort of speed. 4 lo is used for crawling up or down hills, pulling and any situation where you need maximum traction and torque. |
Originally Posted by Donnie_K
(Post 1201534)
Doesn't that in itself mean low load you can use 4 hi, high load you need 4 low?
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Same issue on occasion. Kinda bogs and seems like it's running rich.. I have a bad wire somewhere.. The PCM is also possible at this point, too. It's goin under the wrench on tuesday... And were gonna find the bastard, this time... Either way, I've got this hesitation issue that is messing with the o2's, so that could be the runnin rich issue... Idk...
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Originally Posted by razor02097
(Post 1201388)
The High and Low refers to the gear not the load.
4 hi should be used on trails and loose surface conditions in which you are going forward at any sort of speed. 4 lo is used for crawling up or down hills, pulling and any situation where you need maximum traction and torque.
Originally Posted by VTJeep
Same issue on occasion. Kinda bogs and seems like it's running rich.. I have a bad wire somewhere.. The PCM is also possible at this point, too. It's goin under the wrench on tuesday... And were gonna find the bastard, this time... Either way, I've got this hesitation issue that is messing with the o2's, so that could be the runnin rich issue... Idk...
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Originally Posted by kusman
(Post 1201910)
Well yes, this is understandable. I guess I would just expect the engine to rev more if there is no power. The gearbox already does this anyway: when you are starting from a steep hill, you need to give more gas (higher rpm) to start moving. Following that logic, even in high, it should rev up until there is enough power, not just get stuck on 2k rpm. I am not sure if there is a limiter there somewhere that causes it to do this? Is this normal for an auto transmission or should it rev up like I am assuming?
All automatic transmissions have a torque converter. All torque converters have a rated stall speed. A stall speed is pretty much what it sounds like... you can spin it up to that speed and either the output moves and the RPMs continue to climb or it isn't going to spin any faster causing the RPMs to "stall" at that speed. The idea is you have the stall speed at where the engine makes power. What it sounds like happened is you maxed out the available power either binding the drive train or pulling something. Using 4lo will multiply the torque using the gearing in the transfer case. However keep in mind maxing out the pulling power of your Jeep all the time... you WILL break parts. |
Originally Posted by razor02097
(Post 1201918)
All automatic transmissions have a torque converter. All torque converters have a rated stall speed. A stall speed is pretty much what it sounds like... you can spin it up to that speed and either the output moves and the RPMs continue to climb or it isn't going to spin any faster causing the RPMs to "stall" at that speed. The idea is you have the stall speed at where the engine makes power.
What it sounds like happened is you maxed out the available power either binding the drive train or pulling something. Using 4lo will multiply the torque using the gearing in the transfer case. However keep in mind maxing out the pulling power of your Jeep all the time... you WILL break parts. Thanks, knowing this, I'll try to avoid situations like so that I don't break parts. |
:thumbsup:
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