Hey Anyone, I have codes that indicate O2 Sensor issues. I went to change them out and I saw that one line is marked in a blue tape on each side of the vehicle. Which sensor is connected to the blue tape mark connection? It is not the same on each side. On one side the pre-cat is connect to the blue taped line. On the opposite side the post cat is connect to the blue taped line. This may be the whole source of my problems. I would check the manual but the one I have is for a Motronic 2.7. Laserman
If your blue tape is missing, you may be able to identify the correct plug by wire colour or wiring checks to the ECU. F355_5.2_Engine_Control_System Wiring (non-F1) Diagram
Once again your wiring diagram saves the day. The car came this way from the place I had it rebuilt at. I am surprised it ran at all. We will see how long it goes before another CEL. Qavion, do you know what the output of the Pre-cat sensors is supposed to look Like? I get a sawtooth wave form in real time an my scanner (From .05 to .83 volts.) The Post-Cat sensors are nearly horizontal at .05 to .07 volts The car seems to run and accelerate well and not much of a burble when dropping back to an idle now.
Coincidentally, there was a discussion on this yesterday. The fronts are supposed to be going up and down within a certain range. The manual has some odd wording: "The voltage signal generated by the oxygen sensor fluctuates between 100 and 900mv and changes in steps when the excess air factor is within the range lambda = 1 (fuel to air ratio)" Are you sure about the voltage scale on your scanner? I was told yesterday that the rear sensor waveform is flattened courtesy of the cat material. See "Headscratcher" thread.
That is correct and it is actually due to the ability of the catalytic converter to, amongst other things it does, store oxygen. With very little or no oxygen reaching the post-cat O2 sensor, its voltage output is steady. However, when the cat starts losing its oxygen storing capability (due to aging or damage), the voltage of the post-cat sensor will start fluctuating, more and more as the cat's functionality diminishes. Reading the voltage of the post-cat sensor is a good way of determining the condition of the cat. So, the pre and post cat sensors are of the same type (Zirconium Dioxide in this case), only the ECU will interpret their signals differently - it expects fluctuating voltage from the pre-cat sensor (which it uses to adjust the mixture) and steady from the post sensor telling it the cat is good. If you swap the connectors (the two different signals), the ECU will "think" the cat is bad and will be confused with a steady voltage it uses to adjust the mixture. As both O2 sensors are of the same type, one would expect that they would be similarly priced but they are not - the post-cat one is almost 3 times as expensive as the pre-cat. Maybe just due to the Ferrari pricing, or the post-cat one is of very special construction (Ziconium with some Diamonds?).
Qavion, F355_5.2_Engine_Control_System Wiring (non-F1) Diagram I tried to look at this diagram today and the system said it is no longer available. Could you send your most current diagram for a 1997 Canada Berlinetta 6 speed. Still trying to chase down a P0153 pending code. Regards, Laserman
Irrespective of the version, if you click on the Dropbox preview button, then push Print once or twice, it allows you to save the diagram as a pdf file which can be enlarged to any size. A rather obscure property of Dropbox.
