sgs351

Interesting site. I went through all the threads to find something specific, and I'll admit I learned alot. Didn't find my specific question, tho , so I figured I'd ask you experts. My problem is a failed emissions test. I read the articles on emsissions tests, and found interesting things about rerouting air pump discharge hoses, tuning the varibale resister way lean (where is that thing, by the way?) and alcohol use. Not ready to go that route as I suspect I have a differnt probelm. I know the rotaty runs rich by nature, and I know rich exhaust can kill cats, but I think I have engine deterooation probelm as the main culprit. When i change my oil ( every 3000 miles, by the way) the oil is noticably thin and smells of gasoline. My muffler outlet pipes are sooty, and the sprk plugs are also sooty. Also, my fuel mileage has dropped off to about 20 MPG when I used to regularly get about 23- 24 MPG. This did not come on overnite, but has been going on for at least 6-7 years (I am the original owner and the car is 14 years old). I suspect my seals may be deteriorating to the point where the mixture is overpowering the cats. I failed an emissions test two years ago, and after a go around of replacing the TPS, O2 sensor, spark plugs and correcting a rough idel problem the car would still not pass. Ran very smoothly, no idle problems and performed well, but no pass. I replaced the convertors and I passed with flying colors. Two years later (present day) I tested for emssions and failed again. Almost the same numbers as when I faield two years ago the first time. Based upon this I am of the opinion that the overly rich mixture is killing my cats. I also think that replacing the cats will allow me to pass the emissions test, but the rich mixture will kill the cats and I will be in the same boat two years from now. Any thoughts? Any simple cures to the overly rich mixture situation or are we looking at a complete engine teardown/rebuild/replace option here?

Thanks,

Scott S

inflatablepets

First of all, How many miles are on the car?
Second, How long ago did you change the oxygen sensor? If you can't remember then it's probably time to try a new one. The Bosch universal is $17.00 or somthing like that. How about the injectors? They might need to be cleaned and blueprinted. I don't know how much that costs though. Keep us posted because I also have a S5 that I might have problems passing emissions. mainly beacuse I have a S4 engine in it.

sgs351

Thanks for the reply. Unfortunately during the first go around in 2002 I replaced the O2 sensor and had the injectors flushed and checked. No problem with the injectors. The engine runs smooth as silk, a steady 700 RPM at idle. I had the compression tested in 2002 and it was normal. I need to do that again. The car has 67,000 miles on it. Although that does seem low the majority of the miles are high speed highway driving. I heard stories about carbon build up and slow death that city driving can bring to the rotary.

Scott S