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

open loop closed loop please explain

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Old Jan 25, 2008 | 05:28 PM
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Default open loop closed loop please explain

i took my car in for new gaskets(all of them)and have them change the o2 sensor the guy said he doesent think the o2 sensor will cause the rich idle condition that im haveing --i had code 63 will some one please explain open loop vs closed loop by the way the cats have been empied
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Old Jan 25, 2008 | 05:33 PM
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What year is your car?

Code 63 means there is a break or an open along the O2 sensor circuit. I'd start by checking the wiring to the O2. This would obvisouly affect driveablity. So either your O2 sensor is fried, or the wiring to it.

Last edited by 86PACER; Jan 25, 2008 at 06:19 PM.
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Old Jan 25, 2008 | 05:56 PM
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Originally Posted by robertallen
i took my car in for new gaskets(all of them)and have them change the o2 sensor the guy said he doesent think the o2 sensor will cause the rich idle condition that im haveing --i had code 63 will some one please explain open loop vs closed loop by the way the cats have been empied
Depends if it is a problem with the front or rear O2 sensors. Rears won't effect the way the engine runs. Fronts will.

Open loop, the car is running off table values in the computer and cannot adjust based on sensor feedback (there is an open feedback loop)

Closed loop, the car is starting with the table values and adjusting based on feedback from the sensors.

Make sure the sensors are plugged in and the wires are not burnt or broken.
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Old Jan 25, 2008 | 06:36 PM
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the wires are fine i hoping its just a bad sensor the car is a 1994 i think there are only 2 sensors that are before the cat but i would think a state certifryed wrench would know that the sensors ajust the fuel intake???
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Old Jan 25, 2008 | 08:22 PM
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Go someplace else. Immediately.

If you can't work on it yourself, FIND a corvette shop. Ask the folks on the forum for a recommendation in your area. It takes a lot of time to call around but that work is nintey percent of your eventual success in getting it fixed right and for a reasonable price..
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Old Jan 25, 2008 | 08:34 PM
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Originally Posted by leefarah
Go someplace else. Immediately.
And please fill out your profile.

The '94 has three O2 sensors. Two are precat and one is post cat. The precat sensors are actually used to adjust injector pulse width. God only knows what the post cat sensor is for. Many installing headers don't install the post cat sensor or emulator and have no troubles.
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Old Jan 25, 2008 | 08:35 PM
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i did not find this out until after they already started working on the car and i started asking the guy questions- i took it there for gaskets--oil pan, valve covers, timeing chain cover,intake gaskets, while they were at it i figured they could put the sensor in for me--WOW NOW IM WORRIED!!!!!!
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Old Jan 26, 2008 | 11:52 AM
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just saw the car they are doing a super job i wont have any oil leaks any more, this car leaked so much oil the rear shocks are covered(i wont have to worry about rust) cant wait to see how it runs with the new o2 sensor
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