I dropped my ITA project/street car off at the local independent VW shop last weekend. I wanted an expert to look it over and get it into a good stock state of tune so I would have a baseline for improvements. It has the stock cast manifold, dual outlet downpipe into a gutted catalyic convertor shell.
Today they called and said since the cat was gutted, the o2 sensor would not get hot enough to get into the normal range. This car uses the 3-wire sensor, so it's electrically heated. But in the shell of the gutted cat, it is sitting out of the main flow of hot exhaust, so I guess it is running colder than it was designed to.
The tech recommended a new catalytic converter. Since the car passes smog without it, and it's future as a street car was doubtful anyway, I would prefer not to add a cat. So what to do? We are at an impasse - he won't go any farther without a cat, and I won't put a cat on it (other than an occasional black one .
So how do I get the thing working like it is supposed to? I wasn't really planning on headers at this point, though that would probably give me an opportunity to move the sensor. If I move the sensor into the narrower pipe of the downpipe, it would restrict the flow a bit.
I know some people just cut off the sensor and deal with the mixture in other ways, but I'd prefer to let the CIS do what it is designed to do, and imfluence the mixture as needed with potentiometers or whatever is called for.
So what to do? Suggestions?

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