Hey All, about two weeks ago I noticed my jeep falling on its face when trying to climb hills. There is a hill near my house on the freeway that is pretty steep and before I used to be able to drop the jeep into 3rd (automatic) and drive up the hill at 70 no problem. Now, the last two weeks I drop it into 3rd and it can't even maintain 50 mph! It drops all the way to 45 (with the gas pedal to the floor) and then kicks into 2nd before it can pick up speed again. I have changed the oil and the sparkplugs recently but I am not sure what else to check. Here are some of the symptoms I have noticed recently and any insight would be much appreciated:

1) Rough/Lumpy idle when in Drive or Reverse
2) Regular idle when in Park or Neutral
3) Drives fine on FLAT ground except for a strange vibration in the steering wheel at 35 and 45 mph
4) Normal power on FLAT ground
5) Extreme lack of power on INCLINES
6) Terrible gas mileage, ranging from 10 mpg to 13 mpg

Thanks,
John

 

Mine does the same thing. I was told it could be, Cat, oxygen sensor, injectors. I replaced the injectors today and passed emissions with flying colors, haven't tested it on hills yet. Mine is a 5 speed. It would be nice to know what the fix is. Im dealing with vacuum leaks as well...23 year old jeep....

 

I see. I was thinking it could be the O2 sensor. The cat is less than a year old and the fuel injectors are only a few weeks old.

Does yours accelerate fine on flat ground?

 

yea its either cat or 02! any check engine light??

 

No check engine light. Is there a way to check the 02 sensor?

 

well my 1st guess is a plugged CAT cause there is no check engine light. but u could check it by unplugging one of them and let it idle and if its rougher then its not that. same with the other one

 

Yes it does fine on flat ground, even better going downhill

Going up a hill it seems like it looses all its compression, but sometimes its fine, so whatever it is its not constant. So im betting O2. Let us know if you find the fix.

 

Ok, I unplugged the O2 sensor for my drive home today and nothing changed. My drive is only 3 miles though, is that enough?

It didn't even throw and engine code so maybe I need to drive further? The only code I have after checking is a 17 which means engine is staying cool too long. Not sure if that would have anything to do with this.

 

It is true that at WOT the O2 sensor isn't even read? Cause I am definetely at WOT going up hills with no power so if that is true, it definetely isn't the O2 sensor. It is also only going up hill in 3rd or 4th gear, if I drop down to second it has plenty of power.

 

If the engine's staying too cool, I wonder if its running too rich? I'd clean and check sensors first. Have you ever run seafoam through it?

 

What you describe is text book excessive exhaust system back pressure. If your engine runs too cool, could it be running rich because it's staying in open loop? And will excessive hydrocarbons cause the converter to run too hot to the point that it may become restricted?

 

I have definetely seafoamed it before and I don't have any knocking or anything.

It certainly could be a clogged cat. If you hold your hand 6 inches infront of the tailpipe should you expect the exhaust to be SUPER hot? I did that and it was like I was holding my hand over an open flame and I didn't expect that. I would think if the cat was clogged the exhaust would be really hot maybe.

 

When was the last time you serviced your tranny?

 

ok, then my guess is a clogged cat

 

I've seen one truck driving down the interstate at night with the catalytic converter so hot it was glowing orange. I've also seen another truck waiting at a stop sign with the cat on fire unbeknownst to the driver.