I bought my 89yj about 4 months ago , my first Jeep.... I thought I wanted more power but after reading several threads on this forum about how much of a dog the 4cyl is, I am now wondering If my 2.5 has been modified previously.... the guy I bought it from had absolutely zero knowledge of the Jeep as he had just bought it himself, and I have noticed while working on the Jeep that all the engine gaskets are new& it is obvious that whoever was the previous owner was a good, meticulous mechanic .
my question is this: my yj does 10mph in 1st , 30in 2nd, 45 in 3rd , and easily 65mph in 4th gear, I routinely do 75mph in 5th gear& could go 85 I'm sure but would be a bit scary I think..... i can accelerate up hill in 4th gear.....is this normal for the 4cyl?...
I will check & get back to you ,but I've been under the Jeep many times....... seems stock , although it may have been re-geared possibly, I do suspect that If it is stronger than usual for a 4cyl Jeep it is probably the engine ..... I'm just not sure If this performance is unusual ......it's not a speed demon by any measure, but it is quite capable.... I can actually get the holeshot at a stoplight If I get on it a bit.... ha
Not sure If your MPG question was to me or Dwayne but I average about 15mpg..... the idea that my Jeep has been re-geared seems reasonable except that
1: it has much torque in low gears
2: the drivetrain was rusty& neglected( ujoints all shot, bolts rusty& original, gaskets all appear to be old)..... at the same time, the engine is fresh, clean & well maintained....idk...... mabey this is common performance for a fresh 4cyl?
I could push my 2.5L heap to 80 stock with the 29" tires and a good tail wind. There is nothing that I know of that someone would do to make the engine perform better. The 2.5L is a good engine but just runs out of juice fast.
Maybe the previous owner put in a speedo gear for 32" tires instead of one for 31's! Actually, I did that when I first got mine; the speedo always read higher than what I was really doing, but it felt good. Mine seems to be inline with the performance of yours; I have a Jasper engine with 30K on it with all good lines, sensors and gaskets. As you said, no speed demon, but it gets the job done with a lesson on humility now and then!