My car is running poorly at high RPM's (5000-6800) with cc306, stage II heads, 1.6rr, and I have 255 fuel pump and 30 lb injectors, true 3" duals. I think that I made a mistake with O2 sensors. I cut and extended the O2 wires by myself all the way back by the transmisson, passed my hooker headers.. I even had the end of O2 sensors bent a bit so they would fit in my exaust. When I was dooing it, I thought O2 sensors wouldn't affect my performance, but know I was wrong. Can O2 sensors affect my performance at higher RPM's. Is there the way to test what is impeding my performane. I know it has to be a fuel mixture, but what is causing it. Could it be stock fuel pressure regulator. I heard about the computer scan, but I don't know too much about it. I do have a good computer programming done.

Tomas

 

Never cut the oxygen sensor wires. You need to buy the O2 extensions that are sold at thunderracing or wherever you buy from.

 

As pointed out above, do not cut the wires on the sensor. If you have to extend them, and you have to do it yourself, at least limit the cutting to the harness wires. Then you need to be sure you have the PERFECT splice.... remember.... the O2 sensors are working in 1/1000ths of a volt. A poor splice will screw them up royally. So will running the sensor or harness wires too close to a plug wire.

You said you "bent the ends of the sensors"..... you've got to be kidding. And yes, O2 sensors can affect WOT performance. The PCM uses what it learns in closed loop to fuel the car in power enrichment (PE) mode. If the PCM was "adding" fuel in closed loop, it will use the long term fuel corrections (BLM's) from Cell 15 for WOT.

 

basically new oxygen sensors and wire extensions from thunderracing should fix the problem. Is there any way tracking the performasnce of O2 sensors?

 

you can cut the wires but you have to use the same properties, hence, shielding, silver wire (02 sensor type) vs copper and correct gauge, most importantly soldering these vs connectors. I'd also recommend using heat shrink for a clean job. I did my extensions myself and they are top notch and run pefect WOT. It just takes a little more effort to build the ready-made extensions, no biggie.

 

You are never supposed to spice or solder O2 wires. A Delphi and Bosch class I attended told us the sample air the sensor uses comes through the wire. A solder joint would plug the opening. The O2 sensors are not used under WOT so if your problem is then, your O2s probably are not the problem. I would still fix the wiring though. You may be leaning out because of an injector problem or fuel delivery problem.