Help me out here JK's...

I was trail running up in the Sonora Pass above Bridgeport, Ca. last weekend and when driving up above 9,000 feet the Rubicon went into some sort of a "limp" mode.

The engine just wouldn't rev or downshift when applying full-throttle...

Have any of you experienced the same symptoms? If so, what have you done to eliminate this issue?

Thanks!

BURNDOG

 

Obviously, it COULD be a few things...

The one you hope for (Free fix...) is that your octane rating was too high for the altitude.

You want about 85 octane at that elevation to compensate for the loss in atmospheric pressure, etc...(Regular IS 85 octane at that elevation...)

...but, some times, people drive UP TO the elevation with gas they got down lower, say at 87 octane (Regular at lower elevations...), or, worse, think that HIGHER octane will give more power for the mountains, get "premium" and make it even worse, etc.

I'll start with the free fixes, and see if it rings true, or if you need to spend $ on this.

 

When the wranglers set the world altitude record I know they mentioned one of the jeeps going into a limp mode.
They turned off the engine then restarted with no further problems. I used to live at 10,400' and you would see blacked out test cars up there all the time. Jeep should have tested these things at that level at least and really more like 14,000

The record is 22,597 feet

 

I have seen report that some three stock sahara on a 10 days trip to across tibet, they all experienced significant power lost and difficult to start up when driving above 4500m (14000 ft).

 

About anything runs like crap above 14k however carbureted engines and diesels seem to do better. The carbureted ones have to be adjusted to the altitude.
Also fuel mileage sucks too.

Which doesn't make sense, there isn't enough o2 so the engine should cut the fuel to keep the mixture lean enough so actually it makes more sense to have better mileage. That just isn't what I have experienced.

You can get by with using lower octane fuels because you won't experience any predetonation. I am not sure if using a higher octane fuel with put the jeep into limp mode more quickly. It does stand to reason that the higher octane (harder to burn) fuel would cause a greater loss of power.

Just kinda thinking out loud here.

 

Experienced this going over Wolf Creek Pass (10,800 ft) and Molas Pass (11,800) The JK was loaded with camping/recovery gear the first time and four passengers, one dog and our overnight stuff the second time. I figured it was all the extra weight I was carrying with 33's and 4:10's. Nothing a supercharger wouldn't fix?

 

X2 We deal with high altitude driving all the time and this is correct. We don't seem to have any problem with the altitude so if it isn't the gasoline is it probably a problem with your particular Jeep.