C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

failed emissions

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Old May 7, 2011 | 03:35 PM
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just failed inspection. car passed great at 2500 rpm. failed at 670 idle rpm. co% max to pass 1.2 measured 2.622%. i knew i needed a MAP sensor. went straight to parts store to get MAP sensor. after i replaced it, it was surging badly at startup, then drove it a few miles and idle is better but still has a intermitant rough idle. i have also replaced the O2 sensor reciently. pulled and cleaned the IAC last summer along with new plugs,wires, cap and rotor. all have made it much better. should i drive a few more miles first, or just try my luck again at the emissions?
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Old May 7, 2011 | 04:09 PM
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I'd say disconnect the battery to clear the codes and then drive it for awhile. I assume you have, what, 7/14/30 days to get it re-inspected, right? Drive it until it purrs.
As I understand it, these computers have to "re-learn" the car.
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Old May 21, 2011 | 09:39 AM
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went back same day from reinpsction. all CO2 flat lined at idle and at 2500 rpm. also much better throttle response and better idle. all done for $40.00
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