1998 TJ won’t go past 60

Brokejeep55

Brokejeep55

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Joined
Apr 12, 2021
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2
Location
North Carolina
I recently bought a TJ and have spent the last couple months fixing it, finally got it up and running, and it won’t go past 60? I understand 5th was made for dropping RPMs while cruising; however it will bog down to 55.
it has a 2.5l
31x10.5x15
4.11 and 4.10 gears

from the charts I’ve looked at, it should be perfect highway gears.
Any help is appreciated
 
Last edited:
Brokejeep55 said:
I recently bought a TJ and have spent the last couple months fixing it, finally got it up and running, and it won’t go past 60? I understand 5th was made for dropping RPMs while cruising; however it will bog down to 55.
it has a 2.5l
31x10.5x15
4.11 and 4.10 gears

from the charts I’ve looked at, it should be perfect highway gears.
Any help is appreciated
Click to expand...
Your specs are just about identical to mine. I don't really have any issues cruising at 60mph in 5th, but it's highly dependent on the grade of the road. Driving on flat lands in central PA I can pretty much stay in 5th all the time, but in the hills of WV and MD its a lot of 5th to 4th to 3rd and back.

So many things that could be limiting your power that I couldn't really even make an educated guess. You should be able to cruise in 5th on the highway, but it depends on what your definition of "cruise" is. It's not ever going to be like driving a Camry.
 
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Brokejeep55 said:
I recently bought a TJ and have spent the last couple months fixing it, finally got it up and running, and it won’t go past 60? I understand 5th was made for dropping RPMs while cruising; however it will bog down to 55.
it has a 2.5l
31x10.5x15
4.11 and 4.10 gears

from the charts I’ve looked at, it should be perfect highway gears.
Any help is appreciated
Click to expand...

Your situation is identical to when I had my 97' the slightest hill would get me back to 65. I would say your situation is totally normal. You may not think much of the gradients you're driving on, but they will easily take you out of 5th, with 4.11s and 31s.
 
I would start by replacing your o2 sensors, fuel injectors, and maybe even MAF. I’m doing the same soon on my I-6
 
In 5th doing 65 I would be at 2800, so if you're doing 2700 at 60 seems fine.


Another thing to consider is that the 6 cylinder is recommended 4.10s for 31s, but the 4 cylinder came with 4.10s and 27 inch tires.

20200206_135053.jpg
 
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