I bought '93 325is with 112000 miles 3 months ago and I love it :alright. Right away I changed oil and filter and flushed the radiator. This weekend I'm going to change oil and filter again, but also change sparks, and AT filter and fluid. I was thinking about replacing valve cover, but I don't have time.

My problem is that just recently, I noticed that mufler sound somewhat different than before (sounds like somebody who has sore throath, and like little under water - if this make any sense) and that car definitely has less power while accelerating. While driving I use to kick the accelerator jus a little bit to downshift and accelerate, now I have to floor it and it takes a moment to downshift and pick up, but again, slower acceleration than before and obviously with less power. I checked the codes, and there is no errors - just a code 1000.

My guess is that it might be:

1. O2 sensor need replacement
2. There's vacuum leak
3. AT trasmission fluid needs replacing
4. There's ahole on a muffler or something is stuck inside catalitic converter or muffler.
5. All of the above?

Please advise... :help

Thank you all :buttrock

I would vote for the cat shot. Easy to tell, how much exhaust is coming out the pipe?
At the mileage you have it does sound to me that the cat has seen its day.
I am sure there is a backpresure measure that would tell but in the past I just cut the exhaust system in two before the cat (where it could be fixed by the way) and tried the car to see if it would run right.
Hope this helps.
Sounds like a classic cat plugging to me.

I'm still trying to avoid to spend a lot of money for cat, so I did few things this weekend first (I had to do them anyway) - I changed oil (Synthetic 5W-30 from BMW dealer $4.00 per quart, that's .80-.90 cent less than auto parts stores, including Walmart) and filter. Changed fuel filter and spark plugs. At first moment it seamed as if the car became a little jumpier, but after few days of driving, I can say it is not. Especially, when engine worms up - driving for more than 30-40 minutes, it becomes very slugish.

The only thing left for me to do before cat is to replace an O2 sensor. But, what can I do to save money on cat? Any sugestions?

Thank you...

have a 93 325is here myself need to replace cat but not feeling the price