[KeithO]

My wife's car (1995 BMW 525i) has been slowly losing power and having reduced fuel economy over the last 18 months. I rarely drive the car. 2 years ago, it got about 32mpg on highway trips. Yesterday, I drove it for about 150 miles and only got 25-26mph.

It is down on power and very occasionally smells like a morning-after Guiness-fart. I am 90% sure that the cat is shot. I priced OEM replacement cats and every source I checked was in the $485-$500 range (yikes!). There is also the obvious choice of getting a universal cat and making it fit...

How can I be absolutely sure that this cat is bad? I'd like to be completely sure before I commit the time and potential effort on this.

Thanks

[KeithO]

Yeah, I thought of the plugs and wires. I was planning on starting there when my wife mentioned the car sometimes smelled like a Guiness-fart. (She would know, being my wife. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif) ) Last week I smelled it myself.

Up until now, we've always let the BMW dealer do the scheduled maintenance on the car (my wife didn't want me touching her car - smart girl)... I have to check - we did one of the more expensive maintenance trips recently - the car might have already received new plugs and wires. I need to check that.

If the O2 sensor had gone mad, I assumed the car would be throwing codes. That's why I ruled that out (I could be wrong).

As far as the amount of flow out of the exhaust is concerned, that would be a valid test if I knew how the thing felt before...

What is seafoam?