4.0L Performance - JeepForum.com
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post #1 of 21 Old 10-18-2005, 12:14 PM Thread Starter
bikemanj7
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4.0L Performance

I live at 6200 elevation<lake tahoe> and when i drive my grand around with the 4.0L it is such a slug!!! so i am down in la right now and it is a night and day difference in how it preforms!!! i mean more power, smoother shifting, i can almost get it to burn out! so whats the deal i thought the engine is suposed to automatically adjust for different altitudes? any info on whats going on? i love driving it down here and want her to preform the same at elevation...
thanks- victor


2002 Jeep Grand Cherokee SPECIAL EDITION 4.0L Quadra Trac II
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post #2 of 21 Old 10-18-2005, 12:19 PM
zj333
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this is me guessing buttttt im thinking maybe because the air is thinner at 6200, the jeep is simply not getting enough air, you might want to try a fipk kit or something, thats just me guessing but who knows it could make a big difference. I have the fipk kit and im pretty please with it, i live in richmond virginia so not too much elevation but yeah you get the idea

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post #3 of 21 Old 10-18-2005, 09:44 PM Thread Starter
bikemanj7
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ya i was thinkin about getting one of those i just guess its the elvation bummer...

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post #4 of 21 Old 10-18-2005, 09:52 PM
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yeah i got one, basically for the heck of it, i had a gift certificate i came accross for my birthday (thanks mom and dad) and had nothing else to spend it on so i figured id heard so many good things about it i might as well try it, not toooo big of a difference but it helps a lot in the passing lane, and a little off the line

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post #5 of 21 Old 10-18-2005, 10:12 PM
BlaineWasHere
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Trade your Jeep in on one with a V8!

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post #6 of 21 Old 10-19-2005, 12:06 AM Thread Starter
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i knew i should have got the v8!!!

2002 Jeep Grand Cherokee SPECIAL EDITION 4.0L Quadra Trac II
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post #7 of 21 Old 10-19-2005, 01:03 AM
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It's just the difference in the amount of oxygen in the air, the ECU and MAP can only compensate so much.

Cars at drag strips are always faster at sea level rather than elevated drag strips...fuel injected or carbed.

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post #8 of 21 Old 10-19-2005, 09:00 AM
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he's right, you can only try to mod the I6 to make it a little better thats what i do!

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post #9 of 21 Old 10-19-2005, 10:32 AM
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The computer can only adjust so much - I have the same issues with mine when I go up to the mountains to go skiing in the winter. Being in Seattle, you can pretty much go from sea level to 5000 ft in a little over an hours drive, and you can feel the Jeep get slower and slower and slower...

IMNSHO, performance with the 4.0 is completely acceptable (despite what the V8 owners tell you ) most of the time, but it admittedly sucks once I get over about 3500ft elevation. Turning off OD when heading up helps too, but I'm also geared wrong.

And I have the FIPKII. Doesn't help all that much by. Sounds cooler though!

- Bill (formerly VetteDriver)
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post #10 of 21 Old 10-19-2005, 10:45 AM
gregmondro
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My ZJ is a 4.0l. It does fine here at 5000ft.

I think you're just expecting too much out of the vehicle for what it is.

what is your jeep geared to?

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post #11 of 21 Old 10-19-2005, 10:48 AM
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How ya think I feel when I go from 5300ft to 11,700 ft to go skiing I push on the gas and it just doesn't move. I can't wait until I am skiing with 5 people + equipment + 31's + 3.55 gears @ nearly 12,000 ft...Might have to ask my buddies to get out and push

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post #12 of 21 Old 10-19-2005, 11:01 AM
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Don't get me wrong - it still goes fine at 5000 ft. But the difference between 5000+ ft and 0 ft is like night and day. I've been higher with it too, both in the Cascades and up in Whistler, and I got to where I was going, just not as fast...fast being a relative term.

Of course, it's got 500 lbs. of crap bolted on to it and in it - it will never be mistaken for fast. Then again, the V8 boys aren't actually fast either, just less slow.

My real point was that, if you drive it at sea level and then take it to the higher elevations, it will be a noticeable change. Not a problem per se, but still noticeable. Can you run mods to make it better? Sure, to a point, but even then, the mods are more noticeable at sea level too.

Gregmondro said it best - it's an expectations thing.

- Bill (formerly VetteDriver)
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post #13 of 21 Old 10-19-2005, 11:23 AM Thread Starter
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ya im geared at 3.55 and have not moded anything yet. Thanks for all the info guys!

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post #14 of 21 Old 10-19-2005, 12:00 PM
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Quote:
Originally Posted by VetteDriver

Of course, it's got 500 lbs. of crap bolted on to it and in it - it will never be mistaken for fast. Then again, the V8 boys aren't actually fast either, just less slow.

.
You just say that becuase you have a vette and a S4... All my friends who think they are fast in their Hondas are slow... I'm fast!

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post #15 of 21 Old 10-19-2005, 12:56 PM
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Quote:
All my friends who think they are fast in their Hondas are slow
Now THAT I agree with!!

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