I have a 1987 325-2 (base model, 2 door economy; 5 speed) that was originally from California. It's in good shape overall, but I was suspecting the cat might have been clogged with the fuel economy I was getting (18.8MPG over 118 miles or so, but with 2.5 hours of stop and go traffic -- it still seemed rather low). I went on an adventure of taking off everything from the catalytic converter and back. I'm writing to ask for some advice as to how to proceed.
I found out that the cat looks quite clean, maybe not perfect, but obviously not too restrictive. The muffler's weld where the exhaust pipe enters the back of it is broken, so the pipe moves loosely in it and gasses can escape (it may have been fine before I started messing with everything, but was obviously pretty weak). Running a shop vac through the exhaust didn't cause it to hesitate much, either.
I found out that the post-cat box is a resonator, slightly to my dismay. The only bolts in the whole exhaust system are between the resonator and the cat, the rest is welded solid. I mostly wish I hadn't of gotten into this as the cat and back are all off of the car now, but before I put it together I was hoping to hear from you guys for any recommendations. Might it be worth straight piping over the catalytic converter? Should I take out just the resonator? Is it possible to fix the muffler, or should I get a new one? I'd like it to stay about the volume it is, though I wouldn't mind a touch louder. The tone is nice, although I'm sure could be better. Just if it's possible to do some minor adjustment and get a little more fuel economy it'd be great. I have a small budget but do all of my own work and have a few tools to work with. Also, I live in a non-emissions testing county.
Before taking it everything off, I wrongly mistook the ominous rectangular thing in the exhaust immediately after the catalytic converter as a second cat to meet California's stricter requirements. Does anyone know what changes they made to meet California's emissions requirements?
Also, I tried running it without the exhaust. It was scary how loud it was, even for a 122hp eta motor. I drove it only a short ways, but strangely, it felt rougher and not as powerful (though possibly, just possibly a little more powerful at low (1-2k) RPMs. Any ideas of why that might be?
Thanks!
--Teran
I found out that the cat looks quite clean, maybe not perfect, but obviously not too restrictive. The muffler's weld where the exhaust pipe enters the back of it is broken, so the pipe moves loosely in it and gasses can escape (it may have been fine before I started messing with everything, but was obviously pretty weak). Running a shop vac through the exhaust didn't cause it to hesitate much, either.
I found out that the post-cat box is a resonator, slightly to my dismay. The only bolts in the whole exhaust system are between the resonator and the cat, the rest is welded solid. I mostly wish I hadn't of gotten into this as the cat and back are all off of the car now, but before I put it together I was hoping to hear from you guys for any recommendations. Might it be worth straight piping over the catalytic converter? Should I take out just the resonator? Is it possible to fix the muffler, or should I get a new one? I'd like it to stay about the volume it is, though I wouldn't mind a touch louder. The tone is nice, although I'm sure could be better. Just if it's possible to do some minor adjustment and get a little more fuel economy it'd be great. I have a small budget but do all of my own work and have a few tools to work with. Also, I live in a non-emissions testing county.
Before taking it everything off, I wrongly mistook the ominous rectangular thing in the exhaust immediately after the catalytic converter as a second cat to meet California's stricter requirements. Does anyone know what changes they made to meet California's emissions requirements?
Also, I tried running it without the exhaust. It was scary how loud it was, even for a 122hp eta motor. I drove it only a short ways, but strangely, it felt rougher and not as powerful (though possibly, just possibly a little more powerful at low (1-2k) RPMs. Any ideas of why that might be?
Thanks!
--Teran