O2 sensor problem

[larry309]

'99 323is, manual, I had a problem with balking acceleration,cutting out and missing between 1000rpm and 2000rpm, checked and got a "Pre Cat O2 sensor code". I changed the O2 sensor closest to the cat, still same problem, same code, changed the other O2 sensor, same problem, same code. All I can find are just these two O2 sensors, is there a third O2 sensor further up on the header down pipe? At 70 mph on the high way I get 30+mpg just like I have for the last 120K, acceleration in 1st and 2nd can be balky unless I feather the gas pedal . I really dont want to go to BMW for repair, any ideas will be appreciated.

[Manolito]

I am not certain about the 323, but it should have either three or four sensors. Either two fronts and one rear, or two fronts and two rears like a 328. If your exhaust manifold is split into two banks of three, it has two sensors.

[Jeron]

What was the exact code?

You should have two precat sensors. They in the engine bay on the manifold.

[larry309]

I have found and changed two pre cat sensors, both are before the cat and after the exhaust down pipe. Since I have changed both sensors what could be causing the pre cat sensor code?

[Jeron]

It depends on the code.

It could be a damaged wire.

[larry309]

The car is in the shop right now, it is stuck in first gear, dont ask me I dont have a clue as to how or why, anyway, when I get it back I will confirm the code and check the exhaust manifold for more sensors. I dont remember the code number , but in he Peak book it was "Pre cat O2 sensor".