Hey everyone. so I need some help if possible. I have a 90 2.5l wrangler i bought with serious issues a few years ago and since then. I've went the route of putting a new 2.5l motor and changing it from tbi to carb. so just a week ago i got it all working and even with that I've known it's had other issues... for instance, the transmission has an issue with reverse. so besides that. What the main issue i am having right now that has me a little perplexed is when i test drove it. everything went pretty smoothly up to the point of when i went into 5th gear... when i did that i could barely hold 58mph. it wouldn't go any faster to the floor. only way it would is if i revved the rpm's more in 4th. Now for context it does not have any 31's or any big tires at all. it has the standard tires like any normal vehicle. (this is just going to be a daily driver if possible) im thinking of rebuilding the transmission or buying another, but im just confused on why it wont maintain the speed or gain any in 5th. Any advice would be much appreciated. also there is no issues with the motor in any way on that part aswell. its running just fine. could it be the transmission causing this? or maybe something else?
90 2.5 trouble going highway speeds
- Thread starter kylelneel
- Start date
Your 4 cyl is probably just running out of power and axle gears are too tall to gain speed in overdrive.
Flyer58
YJ Enthusiast
What size wheels and tires ?
Look down the throttle body (engine off) while someone floors the gas pedal and make sure the throttle plate is fully opening. It normally does need much in the lower gears to accelerate.
Look down the throttle body (engine off) while someone floors the gas pedal and make sure the throttle plate is fully opening. It normally does need much in the lower gears to accelerate.
Welcome to the 4-cylinder. Mine was so scary I avoided taking it on the highway. After re-gearing it was a bit bitter, but still it struggled like hell to get past 60 mph.
Go a little faster before changing into 5th gear. I'll cruise to work in my at 70-80 for almost an hour and only have to down shift on the longer hills and if I have a stiff headwind, but it's a pretty flat run from my house to work.
As mentioned above, make sure you are actually getting all the throttle the carb has to offer. Also, make sure you have the jets you need to have in the carb for your area. Arkansas isn't very high, but if you got the carb from a parts store or the like, they don't always overhaul them well. I've seen carbs come from the FLAPS that have the entirely wrong jets in them, probably because some guy on the assembly line just used whatever was in front of him.
If you are running the stock tires then the factory 4.10 gearing should be plenty.
As mentioned above, make sure you are actually getting all the throttle the carb has to offer. Also, make sure you have the jets you need to have in the carb for your area. Arkansas isn't very high, but if you got the carb from a parts store or the like, they don't always overhaul them well. I've seen carbs come from the FLAPS that have the entirely wrong jets in them, probably because some guy on the assembly line just used whatever was in front of him.
If you are running the stock tires then the factory 4.10 gearing should be plenty.