New 95 YJ Jeep Owner

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Rodawg

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Hey guys! I'm new to this forum and to jeeps but I'm 18 and bought my first one so I'm hoping someone can help me.

I have a 2.5 L. 4 cyl. manual engine and I can't get it to go much over 55 mph.

I'm replacing the cap and rotors, plugs and wires, oil and filter, pcv valve and adding injector cleaner.

Any other thoughts on what I can do to improve speed and performance?

Thanks in advance!
 
Rodawg said:
31’s
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Does it do better if you leave it in 4th? You shouldn’t be in 5th gear when driving 55, and definitely not with 31’s. 31’s are a decent bit heavier and larger against the engine than stock.

Also, you’re going faster than 55 when it says 55 if the speedo hasn’t ever been corrected.
 
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machoheadgames said:
Does it do better if you leave it in 4th? You shouldn’t be in 5th gear when driving 55, and definitely not with 31’s. 31’s are a decent bit heavier and larger against the engine than stock.

Also, you’re going faster than 55 when it says 55 if the speedo hasn’t ever been corrected.
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Ohh that makes sense, yes it definitely does better in 4th gear. When i shift to fifth gear, it feels like there’s no difference in power.
 
Rodawg said:
Ohh that makes sense, yes it definitely does better in 4th gear. When i shift to fifth gear, it feels like there’s no difference in power.
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Try driving it in 4th only going 70-75. If it feels good then that just means you need to regear to use all 5 gears. You won’t hurt anything driving it in 4th. And you can use 5th but it will be frustrating if it doesn’t have enough power to pull itself.
 
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Your Jeep probably has 4.10 gears, 4.88s and 32" tires put my speedo right back to factory.
@machoheadgames is exactly right, not using 5th won't hurt anything.
I hadn't even seen 5th until I re-geared, I also have the 2.5 Low Output.

And welcome aboard!
 
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jeepjoe43 said:
Your Jeep probably has 4.10 gears, 4.88s and 32" tires put my speedo right back to factory.
@machoheadgames is exactly right, not using 5th won't hurt anything.
I hadn't even seen 5th until I re-geared, I also have the 2.5 Low Output.

And welcome aboard!
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Alright i will try and see if i have enough power to get up to 70-75 in 4th gear and if not i will try regearing it, thanks for the input!
 
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I have a 91, 4 cyl,5 speed. Stock 4.11's and 31's. I rarely use 5th and that's if i'm on a slight down hill or perfectly flat with no head wind. In 4th im turning 3200 rpm or so doing 65 showing on the speedo. On perfectly flat ground, no wind I could get it up to 75 or a tad more I suppose. I do live at 7500 feet elevation so that takes a bit away right off the top. 4th is 1 to 1 ratio in the trans and perfectly fine to run that way as well. Keep in mind every pre overdrive years truck,jeep, landcruiser with a manual trans ran a 1 to 1 final ratio and they'ed go hundreds of thousands of miles like this. Might wanna throw in a new fuel filter while at it and a O2 sensor as parts are cheap, basic champion plugs are fine and make sure you have no brakes dragging as in adjusted to tight or have a overstretched E brake cable due to a big lift. Also do you notice any out of the ordinary heat or smell off the cat as in its plugged up or self destructed internally. The 4bangers are great little off roaders but not freeway flyers. Be forewarned if your efforts for more HP, $300 so called "cold air intakes", K&N filters and hot rod mufflers wont do much but empty your wallet.
 
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jeepjoe43 said:
A re-gear isn't cheap, unless you're one of the Gotbuckersons, save up your nickles.
It'll be worth it.
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Ha! You said it. I was birthed from Queen Nobuckerson herself, so getting my regear done was no easy feat. I had all odds against me.

all joking aside, it is expensive for sure but definitely worth it, and certainly adequate to drive in 4th until that point.
 
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or you could trade the 31's for a set of stock size wheels and tires. I'm in the same boat with a 2.5L, 5spd, 4.11, and 31's which is ok for me but all I do is go grocery shopping on flat paved roads at 50mph.
 
Yep, you're problem is normal. GPS says my speedo is 5 mph or so slow at 50-55.

Not an issue for me, I'm not stupid enough to try to make mine go any faster, even that is sketchy. lol
 
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cas said:
Yep, you're problem is normal. GPS says my speedo is 5 mph or so slow at 50-55.

Not an issue for me, I'm not stupid enough to try to make mine go any faster, even that is sketchy. lol
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Oh I have to take that back! I drove mine on the highway for the first time today since changing my front and back springs. I was pushing 63 at a couple spots and it was only slightly terrifying. ;)
 
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Im curious what the tune up did if anything. I had my 91 out on the highway yesterday for the first time in weeks and if your jeep struggles to hit 55 in 4th of 5th something else is up besides a basic tune unless the old parts are literally wasted beyond anything.. I hit a speedo showing 80 yesterday in 4th. Thats about as far as id go with the wife in the thing. I look at things this way. If I can down shift a gear in any vehicle and keep the gas pedal exactly in the same place and pick up speed then I was lugging the engine. Thats why I dont use 5th much.
 
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