Few weeks back I started hearing a really loud hissing sound right under the drivers seat, and I knew it was exhaust related, since it was only noticeable when accelerating. I looked under and saw that the small pipe that leads to the smog pump had broken off and was sort of hanging there. This seemed to have no effect on the performance, and just made a louder noise when driving, so I didn't really bother with it immediatlely.

Fast forward to today, the hissing is getting a bit annoying and I run her down to a muffler shop and ask if they can simply weld the pipe back on. Much to my suprise they got it back on there, and only for 25 bucks.

All is fine until I hit the highway, and holy crapola, I have NO power at all. 0-40 is fine, but once I hit the 45 mph mark, I can't go any faster. I'd push the pedal down further, but it would just reward me with a very loud humming noise (which would get louder the further I pushed the pedal) and bog down untill I let off it. It seemed to get worse, and goodness, even the slightest hill was a nightmare to get up.

So, now I'm wondering if the muffler is clogged somewhere, which blew the smog pipe off to relieve the pressue. Do these symptoms sound like a clogged muffler? Or is there something else I should be checking.

Thanks
-Nat

 

That exactly what I was thinking right up to the point where you wrote this.

 

Maybe not the muffler, but a clogged CAT instead.

 

I kinda of agree with stev on this one. While I am not saying a clogged or blocked muffler is not possible, I just have never had it happen. I have had a clogged and/or blocked Cat. Keep in mind if your Catalytic converter is clogged and gets clogged enough, it does has a possibility of catching on fire if it gets hot enough. So I would get that checked out quickly.

Jason

 

Thanks for the replies. I haven't driven the beast since this has happened, but now I guess I have to cut that smog pipe back off so it can breathe, and get it down to a muffler shop.

I'm really hoping this blocked cat-convertor was the cause of such bad gas mileage I was having. I knew as a heavy conversion van that it wouldn't be great, but dang, I honestly feel like I was getting about 6-8 mpg. Of course no overdrive is probably going to have an effect on that as well...

One fix at a time though.