Okay, I know this post is going to be very vague but it's worth a shot seeing if anyone else has experience something like this.

For the last 6 months or so it seems the Jeep has lost its smoothness and power. The main problem is when I'm driving uphill or during any type of acceleration there is this noise under the driver's seat of the car. I've been searching the forums and I have the same symptoms some people were experiencing with exhaust problems and leaks. I've checked if the exhaust was loose and I checked for any type of black soot as recommended and I couldn't find anything. The exhaust pipe is just rusty from the rust-layer and nothing appears to be abnormal. I've checked the connection where the exhaust splits right under the driver's seat and I don't see anything loose or wrong. I'm not really an expert in these things so it could very well be the problem and I'm overlooking it. The power problem is essentially this rattle. It sounds like a rattle, and it feels like it's losing power when accelerated. This is why I think it is an exhaust problem. If the suggestion is a loose shield or something I've checked for anything loose and so has the dealership. I have not approached them that I think it is the exhaust problem and when the drove it they said nothing was wrong. For the most part, I believe them because it's a very slight thing. The other side to this problem is that it happens about 90% when I'm driving. For example, I can start my car and it will run like this and like crap but I will get out and go to the store or something and come back and the ride home will be perfect. It's the worst when the car hasn't been running for a while. Usually after a long road trip (100+ miles) it will run fine.

So this is all of the symptoms and everything I can think of. Overdrive doesn't solve the rattle problem. Any other ideas? Should I take it back to the dealership and suggest its an exhaust problem? The dealership probably wouldn't spend enough time diagnosing the problem and would just tell me nothing is wrong again. I don't blame them though, this problems a pain. Thanks.

 

A good way to find exhaust leak is to start it in a cold morning and watch the smoke

 

it sounds like the catylitic converter honeycomb has broken loose and is shifting around obstructing the exhaust on the left side. The YJ's were NOTORIOUS for this. Sounds like a little noise or rattle at first. As the ceramic honeycomb in the converter moved around and its edges chipped off it got smaller and smaller till it sounded like a brick banging around. Something to check anyway.

 

found anything?

 

There doesn't seem to be an exhaust leak. I can't find any leaks on the start up.

Tinman, how should I check on the catalytic converter honeycomb? The catalytic converter looks fine from the outside.

Also, if this is any help, the Jeep runs much better in below 32F weather. It's still not 100% right though.

 

you can rap a cold converter with the palm of your hand, or a rubber mallet. If the honeycomb is loose it will rattle. A loose honeycomb will shift internally with the road surface bounces and bumps causing intermittant exhaust obstruction and rattles. This is why sometimes the vehicle runs great and other times, often on the same outing it runs poorly or with a lack of power.....might not be your problem but something to look at....

 

An exhaust leak will be heard. It won't generally rob power. It does sound like a cat. problem You can either have your dealership troubleshoot the problem as you probably have a lifetime powertrain warranty like I do. Otherwise you can disconnect the exhaust and drive it around and see if your power loss is resolved. Either way the cat. will be under warranty and replaced by your dealer if there is a problem.

 

If you drill a 1/2 " hole in the exhaust before the cat and it picks up power you can be sure it is in the cat where the problem lies. But do the tap test first.

 

It may seem weird but try running a tank or two of premium fuel. Being from the north, your also having to use the so called winter blend of gas. I've noticed a lack of performance and fuel mileage since they changed to the winter crap last month. Give it a shot and see if it helps.

 

Try a couple tanks of mid grade gas. In my area 85 octane is the norm and I think that is too low. 89 octane and my jeep runs smoother.