I took a drive out to the mountains last week. Some of the mountains are steep but the majority aren't to bad. After about 20 minutes of driving up and down the mountains my XJ started to feel like it was struggling to speed up or keep a constant speed (like the brakes were engaged). In the beginning I was traveling at approx 60 mph and at the end it wouldn't go over 25-30 mph. At one point I had to stop because I though something was wrong. After about a 10 minute rest, I continued on. At first it was fine but it quickly started doing it again. After my trip I didn't drive my jeep for a few days. Yesterday I drove on a flat highway for about 3 hours. Towards the end of my trip my XJ started to have a problem keeping a constant speed. No matter how hard I pressed the gas it kept wanting to slow down. The engine temp was normal at 200-210. I'm thinking the tranny is getting overheated. After I stop my jeep I don't smell anything out of the ordinary. Any Ideas???

 

I just spoke to a friend who is a mechanic and he said the Cat might be going bad.

 

X2 on the cat converter

 

Or fuel pump

 

Yep, Catalytic Convertor is getting plugged, OR you could have a brake dragging, but I would imagine you could smell it.
Old rubber brake lines can separate internally allowing fluid in, but the pressure can not bleed back out. This always ends with a very hot rotor and the small of brakes burning if it was the case though.

 

I think I'm convinced it's the Cat's. I found direct fit Magnaflow cats online for $80 each. i think I'm going to buy.

Within the last year I have replaced the brakes pads, calipers, lines and Master cylinder. I have a laser thermometer and I'll check the rotors the next time I'm on the highway for awhile.

 

You have to figure out why the cat went bad, or you'll just be replacing it again.

 

What could cause a cat to go bad?

 

it's 11 years old lol

 

Running too rich will kill a cat fast, leaded gasoline will damage the cat, but you can't find leaded fuel anymore. Age is not a huge factor, I still have the factory cat on my 95 and it is working perfectly according to my last smog check two weeks ago.