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Thread: Adding O2's

  1. #1
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    Default Adding O2's

    I have a 427 ci ls1 motor in my 2000 camaro. It was tuned in open loop and I want to put the O2 sensors back in. If I put them in and turn them back on what kind of problems can I run into. Would the car need to be completly retuned or will it be ok.

  2. #2
    Joe (Moderator) joecar's Avatar
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    It should be ok...

    If it was tuned right then the LTFT's will be low.

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    Great thanks I will get them back in and see what happens. If things seem to go crazy I will post back any problems that I have.

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    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Sometimes those O2's get a little lazy, especially at start-up and until you hit your normal operating temperature. But, that can be easily manged by an accurate VE Table and MAF Calibration Table.

    I run closed-loop with a moderately aggressive cam. I personally prefer the concept of a system that is constantly attempting to run your car at or near stoich (~14.7 AFR)..

    My only suggestion is that at some point your look at your tune and your O2 Switch Points. After a lot of logging, I chose slightly higher O2 voltages. Using my wideband, that gave me a consistent 14.7 AFR and my LTFT's are right on.

    Good luck. I am interested in how that engine runs! Let us know.
    Last edited by WeathermanShawn; February 10th, 2010 at 12:38 AM. Reason: Grammer
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  5. #5
    Lifetime Member mr.prick's Avatar
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    I agree with using O2s.
    I flat-lined the switch point @ 450mV and used LTFTs for non PE areas of the VE & MAF.
    LTFTs & PE AFR are right where I want them but
    it's the damn transient fueling that I have trouble getting straight.

    Don't be surprised if you have high LTFTs after enabling CL.
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  6. #6
    Junior Member Frost's Avatar
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    Quote Originally Posted by joecar View Post
    It should be ok...

    If it was tuned right then the LTFT's will be low.
    Just leave the LTFTs off... If the MAF/VE was tuned well enough for good OL driving, the STFTs will be more than plenty correction and if they wander off positive a bit, they won't interfere with WOT like LTFTs will.

  7. #7
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Quote Originally Posted by Frost View Post
    Just leave the LTFTs off... If the MAF/VE was tuned well enough for good OL driving, the STFTs will be more than plenty correction and if they wander off positive a bit, they won't interfere with WOT like LTFTs will.
    Yea, I have not had the nerve to try that yet. I see your point about not interfering with WOT..Frost isn't there a point if STFT's exceed a certain value, then the LTFT's become active?

    I know you will probably say..if your tune is on, then that will not happen. I am just curious if there is any 'side effect' of turning off LTFT's. What happens if STFT's wander off and your LTFT's are not active?
    Last edited by WeathermanShawn; February 10th, 2010 at 12:37 AM. Reason: Grammer
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  8. #8
    Junior Member Frost's Avatar
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    Quote Originally Posted by WeathermanShawn View Post
    Yea, I have not had the nerve to try that yet. I see your point about not interfering with WOT..Frost isn't there a point if STFT's exceed a certain value, then the LTFT's become active?

    I know you will probably say..if your tune is on, then that will not happen. I am just curious if there is any 'side effect' of turning off LTFT's. What happens if STFT's wander off and your LTFT's are not active?

    We are all trying to learn, so anything you can add is helpful.

    Thanks.

    ..WeathermanShawn..

    No, they reach the same limit regardless of the state of LTFTs. LTFT's reach the point of updating whenever a defined ECT is met (typically around 149F OE for GenIII) and the STFT correction exceeds 4%.

    If you are worried about things, set a lower limit on trim correction, though you shouldn't need to do so.

    I think it's a plus in some areas... If you have a misfiring cylinder around idle, the LTFTs will stack on a pile of fuel that will be applied at next cold start if not cleared and further aggravated by the STFT addition.

    If his car ran well in OL, it should be fine in CL with just short term trimming.

  9. #9
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Thanks.

    I am going to try it!
    Last edited by WeathermanShawn; February 10th, 2010 at 12:36 AM. Reason: Grammer
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  10. #10
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    I just turned on the ltft and stft along with using the stock correction values for both. I have yet to get under the car and put them in I hope to do that today. I was curious about the switch point which is at a stock setting also. I will go back and disable the ltft and see where it goes. The cam in there may be small for the motor at 254/254 581/581 112 lsa. Should I try the flat switch point as well.

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