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Old 04-14-2008, 08:37 AM   #1
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Replaced O2 sensor, reset PCM, mpg's plummet

So this past weekend I put a new Bosch front O2 sensor in, and then unhooked the battery for a while to reset the computer. This morning when I go to leave for work, the car starts hard and idles rough, I expected that much, and the mpg's were really bad. What I am wondering is, how long can I expect to wait before the fuel trim tables are reconfigured? I've heard of some not liking the bosch sensors for one reason or another, should I have just went for a better quality sensor? Bosch was all that was offered at autozone. Thanks for any advice.
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Old 04-14-2008, 08:40 AM   #2
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I haven't heard a nice word about Bosch sensors from anyone driving a domestic or asian car.
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Old 04-14-2008, 08:58 AM   #3
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Any specific brand I should be looking for? I am assuming I could get an AC Delco one from the stealership for a premium price.
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Old 04-14-2008, 12:43 PM   #4
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Simply resetting the ECU after replacing the O2 sensor should NOT cause starting running problems. drop a 1-2 mpg for a hundred miles yes, actually run rough no.

check for things like vacuum leaks or broken wires (that you mighta caused fixing things)
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Old 04-15-2008, 05:05 AM   #5
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It only idled rough for a little bit after starting, it is fine now. I realized on my way home yesterday that when I had the battery unhooked, the scangauge went back to default settings. Not sure why, it is supposed to be kept in flash memory and my custom xguages were still set up. Anyways, the engine size was off, and that was what made me panic. I set that straight and it is now just a little lower mpg than usual. I will give it a few weeks and if it does not improve, I will try and find an AC Delco replacement.
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Old 04-15-2008, 05:54 AM   #6
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Some chevys are known for hard "relearn".
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