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Well i went to autozone and they have verified to me that both my primary and secondary o2 sensor are no good. The secondary was replaced at the time of install of my header with a brand new one. and the primary was good before the install.

My question is: Is it possible with my setup that my car is running to lean or something and fouling out these o2 sensors or was it more than likely an install issue of them banging them up a little too much? My mods are CAI,DCRH,DC catback,Reflash and TWM SS

also as i cross over 4k rpms @ normal throttle I get a little metal on metal sounding rattle just for a split second til like 4200rpms. It sounds horrible and can be heard outside the car too... what do we think this is? the connection of the header to the exhaust or the hangers or what? Im kind of ruling out the hanger issue because i think you have to have metal on metal for that type of vibration...

thanks in advance
Josh
 

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You have the Hondata reflash, I assume? They do a tremendous amount of research and testing before releasing software, making sure things aren't too lean. I would assume the race header is the cause of your problems.

The secondary sensor that you replaced; was it replaced with a non-stock large-band O2 sensor? Any time you replace a stock component and the ECU has to compensate, you increase the risk of problems, even with well-engineered aftermarket software. The absence of a catalytic converter adds another variable.

Check to see if you have a proper seal between the engine exhaust ports and the header; make sure the gasket is not leaking. That would provide inaccurate measurements for the O2 sensors, which in turn would lead the ECU to compensate for non-existant conditions, which could make you run too lean, which would put undue stress on the O2 sensors. It would also explain the metallic rattle you are hearing.

Just a guess. It's hard to tell without more specific details.
 

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Well, the rattling probably means that one of the parts you installed is a bit loose. I suggest that you first retorque your exhaust manifold bolts and check for leaks. Also, what kinda CAI do you use? I believe some people here have had rubbing issues in the engine bay, try a search.

Also, I suggest you look through the forums at www.k20a.org and www.honda-tech.com. Those sites are a bit more suited to answer in-depth technical questions.
 
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