when do O2's come into play? - TCCoA Forums
 
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post #1 of 10 (permalink) Old 01-05-2004, 05:04 PM Thread Starter
 
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when do O2's come into play?

I only have the drivers side O2 hooked up in my 93 bird. The other one was broken in the engine swapping. I do plan on replacing asap. It doesnt seem to affect the driveability at all, good idle, good power, smooth runner. The CEL comes on after its warmed up and goes on and off, of course for the O2... My question is does the EEC read the O2's in closed loop, like when its cold? Thanks.
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post #2 of 10 (permalink) Old 01-05-2004, 06:15 PM
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I think closed loop is a programmed air/fuel mix for safe running of the engine. So it's not using the o2's at all, just a preset mix.

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post #3 of 10 (permalink) Old 01-05-2004, 07:08 PM Thread Starter
 
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so do you think its defaulting to closed loop due to the lack of an O2?
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post #4 of 10 (permalink) Old 01-05-2004, 07:27 PM
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that would make sense.

When I totally redid my exhaust I put on 96 shorty headers, which do not have o2 bungs like the earlier ones do. I unplugged both o2's and drove to the exhaust shop on open headers (which was really fun by the way ) but my air/fuel gauge showed me I was in closed loop the entire time.

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post #5 of 10 (permalink) Old 01-05-2004, 11:41 PM
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Or it might just be using all of the info from the left-side sensor. At any rate, open loop indicates no feedback from the sensors and info is read from a table in the ECM. Closed loop is the mode where the O2s are sending data back to the computer. I think you guys are mostly right, just backwards.

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1994 Super Coupe ('93 5.0L swap), 1990 Tbird 3.8L, 1982 Honda CB900F, 1972 F-100 SportCustom 4x4, 1970 Chevy Custom Camper / 20
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post #6 of 10 (permalink) Old 01-06-2004, 01:22 AM
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yeah you're right, just a typo there.

I think it would go into open loop if just one O2 were bad, other wise it would be reading the air/fuel mix from just the other side of he engine, which would not necessarily be the right air/fuel for the other side of the engine.

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post #7 of 10 (permalink) Old 01-06-2004, 07:24 AM Thread Starter
 
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I couldnt remember open or closed, thanks. Its either reading the set table and doing a good job of it, or the other sensor is right on the money. It still got 400 miles to a tank of gas!
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post #8 of 10 (permalink) Old 01-06-2004, 12:50 PM
 
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Don't mean to hijack the thread, but where are the O2's located on our cars, i was looking under the hood and looked at the end of the factory headders and what looked like a O2 sensor, but it was the same on both sides of the engine, i was under the impression one sensor was on the motor and the other was downstream on the exaust.

Thanks,

--Dan
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post #9 of 10 (permalink) Old 01-06-2004, 02:29 PM
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both are on the exhaust manifold or downtube depending on the year of the engine. It looks similar to a spark plug with a few wires coming out of it. There is one on each side of the exhaust.
-Thomas

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post #10 of 10 (permalink) Old 01-06-2004, 02:40 PM
 
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Thanks for clearing it up, I don't know where i remember reading it was located elsewhere, curse my fuzzy mind lol
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