Bozo

2001 Cavalier 2.2 5-speed manual 232k miles.

So over the last month or so - but especially the last week - I have had some weird new problems all come up at the same time that I initially thought were unrelated but now think are all a result of the same problem. I have had this extreme condensation accumulation inside the car - but it is worst in the back and inside the trunk. I mean everything is literally dripping wet caused puddles of water. It is on every surface of everything inside the trunk and every morning, I get out and all my interior windows are all fogged-up and wet. At the same time, my car's AC - despite still working fine and blowing just as cold as usual - cannot seem to cool the interior of the car. And finally - the section of my trunk that is directly over the muffler - is about 10 times hotter than I ever remember it being. It is like a super-charged space heater or oven is blazing back there..

Have had some minor misfires lately, but no check engine light, a little rough idling at starting up in the morning - much worse after it rains overnight so pretty sure that I need new spark plug wires.

But my question is - what would cause my muffler to be so crazy way-hotter than usual? - because I think all the other stuff is a result of that.

tech2

very bad misfires will send raw fuel into the cat...this can heat the cat high enough to melt the inside structure of the cat

make sure the muffler heat shield is in place

water in the trunk is probably a leak past a taillamp seal or unibody seam sealant. remove the trunk liner, get in and close the trunk. have someone with a garden hose run water all over the rear of the vehicle and rear glass...watch for leaks

kevinkpk

And make sure they let you out! Sorry, it was open, and I just had too.

Bozo

OK. First - while I do have a leak into the trunk, that is a totally separate issue. And I have tracked it down to coming from somewhere around the driver's side roof support over the fixed rear window. It is definitely NOT leaking from the main weatherstrip around the trunk seal, the vent nor the taillights. Those are all bone-dry. The problem I mentioned in my original posting is something totally different - condensation forming from an extreme temperature imbalance that coincided with the extreme heat on the bottom of the trunk above the muffler and last foot or two of the exhaust pipe before the muffler on the driver's side only. The condensation is evenly spread on every surface of every single square inch of all interior surfaces inside the trunk as well as every surface of every item inside the trunk.

I have had this car for over 17 years and this new extreme heat issue is brand new and definitely a huge difference so it isn't something I would have just missed in the past. It is heating up the entire interior of the car - but especially the back seat which is right in front of the trunk and is only separated from the trunk space by the back of the rear seats which drops down to go through to the trunk. Last evening, I parked the car after driving it, opened the hood took a look and a listen and everything seemed to be the same as always no obvious problems. Like I said - no codes being thrown that I know of and no Check engine light which I would expect would be on if I had a bad O2 sensor or cat problem or some other valve or sensor gone bad.

Then I went back under the car where the heat is coming from and smelled the exhaust a few sniffs - nothing out of the ordinary in odor or appearance. No smoke, no rotten egg smell, etc....then I crawled under there and tried to inspect the heat shield situation. I am not familiar with how it is supposed to look, having never had any reason to go under there so I can't compare, but I didn't see anything "falling off". There didn't appear to be any place for any shield that wasn't there however there was only a small metal bracket on only one side of the muffler which to me - seemed inadequate. But I don't think there was anything missing. So I am back where I started - some new extreme heat that is coming from the exhaust near and at the muffler - many times worse than normal with no explanation that is making the interior of the car too hot to tolerate and more than overpowering the AC. The only theory I have heard is that there might be a "hole" in the top of the muffler? I have no idea how I would even check that. I guess I will have to get a mirror and try to see what I can see. But that sure seems like a long shot as everything else under there shows little sign of rusting.

tech2

start the car...put a rag in the tailpipe to block the exhaust stream...if any holes are present...the exhaust will flow out the hole and could be felt by running your hand around the muffler. the system is designed to have pin sized weep holes...anything bigger is a problem.