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High idle problem.

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Old Apr 11, 2019 | 07:10 PM
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Default High idle problem.

I just bought this 99 convertible and it idles at close to 2k rpm. It will idle down after sitting for a few minutes, but still very annoying. It is throwing the following three codes:
  • DTC P0133 HO2S Slow Response Bank 1 Sensor 1
  • DTC P1134 HO2S Transition Time Ratio Bank 1 Sensor 1
  • DTC P1153 HO2S Insufficient Switching Bank 2 Sensor 1
I know these are referring to an O2 sensor, but before throwing parts at it, I was wondering if this is because the previous owner put long tube headers with cross pipe, kept the cats, but removed the mufflers making it basically straight pipes with cats. It also has a Vararam intake kit. So Im wondering if changing the 02 sensors will make any difference???

Thanks for any input
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Old Apr 12, 2019 | 11:07 AM
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i would definitely replace all the o2 sensors. If the sensors dont get the readings it likes, it will throw off your air/fuel mixture. So high or even rough idle doesnt sound surprising.
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Old Apr 12, 2019 | 11:35 AM
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O2 sensor issues with LT's...LOL !!!...that's most likely your problem...bring it to your friendly tuner...search the Forum and you will see MANY with LT's having this issue !!
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Old Apr 12, 2019 | 12:52 PM
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Thanks for the input guys. I was planning on changing them, but wanted to be sure the code wasnt being thrown by the headers. I can clear the codes and it runs great for awhile, but they eventually come back. How many O2 sensors are there???
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Old Apr 12, 2019 | 01:09 PM
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Originally Posted by Zeek
Thanks for the input guys. I was planning on changing them, but wanted to be sure the code wasnt being thrown by the headers. I can clear the codes and it runs great for awhile, but they eventually come back. How many O2 sensors are there???
1 upstream (before cat) and 1 downstream (after cat) on each bank, so 4 total. They have different style connectors so make sure you order the correct ones. One is a straight 4 pin connector, the other is 4 square (2x2). I can't remember at the moment which one of those two is upstream I want to say the straight 4 pin...but someone will need to validate

Last edited by wscott62893; Apr 12, 2019 at 01:10 PM.
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Old Apr 12, 2019 | 01:19 PM
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Originally Posted by wscott62893
1 upstream (before cat) and 1 downstream (after cat) on each bank, so 4 total. They have different style connectors so make sure you order the correct ones. One is a straight 4 pin connector, the other is 4 square (2x2). I can't remember at the moment which one of those two is upstream I want to say the straight 4 pin...but someone will need to validate

DOWNSTREAM is square and the UPSTREAMS are rectangular I guess you can say !!
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Old Apr 13, 2019 | 10:16 AM
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Thanks again guys. I had the Vette up on a lift at the local muffler shop getting the exhaust tips changed and located the sensors. Gonna be a bitch to change with the close clearance from the long tube headers. I cleared the codes and drove all day yesterday with no new codes and idle back to normal. Im sure it throw the codes again, but for now.......well....
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