Installed cat bypass.... now lots of smoke

[chrisbruck]

This weekend I put in a new Bursch cat-bypass along with a universal style Bosch O2 sensor. The rest of the car is stock. Now I get a noticeable amount of blue smoke while decellerating and a little at idle. The car is new to me but it appears to burn a 1 qt around 800 miles. I plan to monitor much closer now.

With the stock cat on there was the occasional sign of smoke but not nearly as much as there is now. Will the cat really mask the burning oil that much?

[Joe Bob]

That's what a cat does.....do a search.

[darrin]

800 miles per quart oil consumption and blue smoke on deceleration both suggest that your valve guides are worn and allowing oil to be sucked into the combustion chamber -- a relatively common occurrence on carreras of our vintage. My similar oil consumption/smoking issue at 80k miles was completely resolved by a top-end overhaul and my 3.2 has performed "as new" (or better) ever since. At 150k miles, I'm getting at least 2k miles per quart. Unfortunately, this is not an inexpensive solution.

[Newlin4141]

Is the cat bypass new or used? I bought a used Fabspeed bypass pipe and it smoked like the devil himself for a while. Yours sounds like a different issue since mine was resolved by just burning off the oil the previous owner of the bypass pipe somehow got in there. Maybe it was from a blown motor. Dunno. But it stopped smoking. Good luck.

[chrisbruck]

Mine is new from Pelican.... thought it was the paint and new gaskets settling in but no, it definitely puts out more smoke now. Gonna closely monitor oil usage and then decide what to do. May put the cat back on. For now it's just an annoyance till I really know how fast it's using oil.

On the plus side it sounds way cool now. Just the stock muffler that a previous owner had a second exhaust pipe cut out and welded on the passenger side

[Newlin4141]

If you want some real excitement, try running just the bypass pipe! I had to drive my 930 from the shop to my house last April with just the Fabspeed by pass pipe on it and was not subtle. [NOTE: I do not recommend doing this, by the way. It's extremely loud.]