by-pass pipe problem??????
 

I have a 911 ,89 model ,3.2 that I put a by-pass pipe on . after
the pipe was installed the car sounds good but doesn't run as good the car seems to be running too rich . could removing the cat. cause the oxygen sensor to not work right ? Does the car need the back preasure and heat of the cat. to function correctly?
The car has 82k on it and is holding 170 to 175 # compression each cylinder , but the plugs were wet. It also seems to be smoking (blue and black) more than it did and has a very rich exhaust smell . Does the car have an egr valve ? do I need an oxygen sensor or to re-install the cat.?

DID YOU REPLACE THE O2 SENSOR BACK INTO THE EXHAUST AND IF SO DID YOU MAKE SURE OF THE CONNECTIONS? IF SO AT THAT MILAGE IT MIGHT BE TIME FOR A NEW O2 SENSOR.

KEITH EPPERLY
87 911 CARRERA CABRIOLET SLANT NOSE WIDE BODY TURBO LOOK

It needs an O2 sensor for the computer to function correctly; a missing or disconnected O2 sensor will make it run too rich. Was there a bung in the cat pipe to reinstall the sensor and/or was the sensor reconnected after the install? A cat pipe will relieve back pressure somewhat (a good thing for your car) and will run cooler than the converter (also a good thing). The black smoke and smell indicates that it is running too rich so you should look into the sensor situation a little further. I put a cat pipe on my 88 and it made a difference for the better. You won't pass a smog test with a cat pipe, tho, if that is an issue.

Argo
88 Targa

by-pass & 02 sensor
 

my car does have the 02 sensor connected , it was hard to get out of the old cat but I did get it in the new pipe . I will check the connection again and if that doesn't help I will replace the 02 sensor. the car seems to take longer to rev and like I said is blowing black and blue smoke and the new 4 prong platium
plugs were wet . thanks for the help!