348 performance

Does the car surge or slow just a little when you are holding a constant speed? If so, it's your O2 sensors. They do go bad over time.

The O2 sensors are ignored at full throttle, too...so you wouldn't see the problem at full acceleration.

 

They are on the front of the catalytic converter. The part that attaches to the exhaust manifold.

Also the O2 sensors have been know to have ground issues. You can connect an extra ground strap to the sensor and then run the wire to the frame.

Do a search of the archives. There are loads of posts on the subject.

 

Hi,

When we remove catalitic converter, we also remove the O2 sensors.
Isn´t that true?
If so, it is possible ride without them when a problem like this happens, even if we have catalitic converters on. The only problem will be not having information about O2 and the information of temperature.
Is this correct?

 

Totally wrong. You MUST have the O2 sensors in place. They are a very important part of the injection system. They help control the air/fuel ratio by measuring the amount of unburnt fuel in the exhaust. If they are not present the engine will not be able to run properly, if at all.

I think what you are refering to is the catalytic converter temperature ecu's. If you are running test pipes you can disconnect the cat ecu's, but you MUST have the O2 sensors connected.

 

This is a picture of a 348 test pipe:

http://ricambiamerica.com/product_info.php?cPath=175&products_id=261103

If you enlarge the picture, you can clearly see both attachments here. Many people who buy test pipes simple plug the thermocouple hole because cat temps are irrelevant with straight pipe. The O2 sensor however, must must must remain in place.

 

a similar situation arose with my f512m lately with the slowdown light coming on quite frequently and the intermittent surges/lost of power when that happens. It turns out to be bad thermosensers for the cat. I might have done something stupid before taking the car in to the dealer and finding out what the problem is: I guned the engine to try to "smooth it out" thinking that it might have been wet spark plugs due to prolonged non-use and starting and shutting the car off when moving from one parking space to another in my garage. would this have done terrible things to the car? now i'm worried

 

Ok..
Thanks for the information....
I saw lot of threads with these information, but it always made some confusion. I thought the O2 sensor and temopar were in the same place.
I have test pipe on mine, and I have the sensor on, but I now understand that I only have the O2 sensor.
Is the O2 sensor an expensive part??

Thanks,
Nuno Maia

 

Nope.

You can buy a generic O2 sensor for about $50 U.S. You will have to splice the connector wires to the new sensor. Or you can buy the whole sensor with the connector for about $120 U.S.

 

Thanks..
It is a good spare to have at home, so we can see if the problem cames from there...

Good information.
Thanks

 

Whoa, they raised their price on the O.E.M sensors since the last time I was on their site. Anyway here is the link:

http://www.oxygensensorwholesale.com/ferrari_1992_348-ts.html

 

The O2 connection is located at the top of both pictures.

When the car is cold (very cold), you'll want to coat the O2 with penetrant oil to make your wrenching less unpleasant. Let the penetrant oil do its thing for half a day or more.

Then just put a wrench (or a socket that has a cut-out to avoid crushing the electrical wires) to it and turn each O2 sensor out.
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You didn't say if your CEL(s) are coming on or not. If they are read your ECU codes first before you waste time doing anything else even if they are not coming on still read your fault codes first. The ECUs have a great diagnostic system built into them. If your CEL(s) are not coming on I doubt it would be the O2 sensor(s). Could be an imbalance in your throttle bodies either the butterfly valves or the air bypass screws are out of adjustment. Regards, Vern