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Thread: HELP idle issue? Wibeband says lean but smells rich

  1. #1
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    HELP idle issue? Wibeband says lean but smells rich

    ive attached a scan of just idle and slight rev.

    long and short term fuel trims are not showing as well?

    thanks

  2. #2
    Advanced Tuner robbyredneck's Avatar
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    add fuel with the scanner and see what the wideband says as well as your nose.
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  3. #3
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    Quote Originally Posted by robbyredneck View Post
    add fuel with the scanner and see what the wideband says as well as your nose.
    U mean the editor? To confirm where do you add fuel? I've been using the fuel vs. Kpa

  4. #4
    Advanced Tuner robbyredneck's Avatar
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    no. when your scanning you can open the vcm controls tab. it says on off 100%
    and it's next to the little engine icon. also where you reset your fuel trims.if you then go to the fuel and spark tab you can adjust the afr in real time.
    04 6.0 silvy china turbo
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    03 stroker evo ww
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  5. #5
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    ok thanks so much.
    i assume you push the up and down arrows to adjust? but then what? i would have to write it to the PCM in editor. but can i read what numbers i can write?
    thanks for your time

  6. #6
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    no you dont have to write it to the PCM, just set the afr to what you want to try and click Force AFR if i remember correctly

  7. #7
    Advanced Tuner robbyredneck's Avatar
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    this is just a check too make sure you truly do have a lean condition. if it's burning your eyes then it's noxious and needs more fuel. then you set up an afr error histogram and adjust your ve table accordingly . try to find lt1birds tuning guide, it's really easy to follow and a huge help in understanding your tune and parameters.
    04 6.0 silvy china turbo
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  8. #8
    Senior Tuner mowton's Avatar
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    long duration cams or air leak can "trick" the O2 into signaling a false lean condition. You may actually have to lean it out. Counter intuitive but it works.

    Ed M
    Last edited by mowton; 12-08-2012 at 01:25 PM.
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  9. #9
    Advanced Tuner JamesLinder's Avatar
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    you cannot use a wide band to adjust idle if you have a cam of any consequence due to reversion (that is, exhaust gas flowing back into the intake manifold due to overlap - when both the intake and exhaust valves are open at the same time which gives a false lean reading). Once you install a performance cam with overlap, you will end up with a rich idle and DO NOT GIVE IT MORE FUEL like you were told to above because if the exhaust burns your eyes you are already too rich with fuel. Adjust idle to get rid of the rich exhaust SMELL and to maximize intake manifold vacuum (minimize MAP) and to minize MAF for a stable

    Multiply stock VE's by 90% from 400 through 1200 RPM, and if still smells rich at idle restore stock VEs and multiply by 85%. You may
    have to reduce stock idle area VE's by as much as 20% or more before you get rid of the rich condition depending on how radical your cam is. If you have after-market intake parts, heads and headers you should probably multiply your MAF curve by 10% across the board as a starting point. I have found that 7.5% increase in idle flow region (3250 hz) is common and a 10% to 15% increase by 8500 hz is not uncommon. Unless you have converted to speed density, the LS motors must have MAF dialed in fairly accurately or else this will throw everything else off big time.
    Last edited by JamesLinder; 12-08-2012 at 01:36 PM.

  10. #10
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    With have a cam with 5degress overlap and it is idling at 11.8-12.3 afr, would it be wise to real time tune it until you have the AFR at idle around 14.7? or what that be too lean for it with a cam?

  11. #11
    Advanced Tuner robbyredneck's Avatar
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    it's a common misconception that "burning eye" exhaust smell is rich, most of the time it is not the case it is lean. co and nox is pretty caustic feeling while raw gas smell is usually an indicator of it being super rich if it will even run. i don't think the op mentioned having a cam and my suggestion is meant as a quick test so you know which direction you truly need to go.
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  12. #12
    Advanced Tuner JamesLinder's Avatar
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    RTT is typically more useful once you have tune in the right ball park and are ready to dial it in for optimization - however, everyone is different and should use what works best for them. Results are what count more than how you get there, and one could not learn if they did not experiment.

    When the car finally idles well at all ambient temperatures, please let us know if it turned out to be rich or lean. Robby and I have a diet Dr. Pepper bet on the outcome.

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    ok thanks alot of info. i believe it is lean at idle cause the wideband tells me so...
    when i set the injector size back to stock size it barely runs and runs at 10 or so afr.

    ok so i do NOT have a cam. it a stock 1998 LS1 with a T56, rear mount turbo, has a SLP MAF and thats it. aeromotive a1000 pump and a bypass reg. fuel pressure is set at 58psi.

    so would me not making changes to the computer for the bigger MAF make a difference in idle afr? thanks

    also i bought the tuning school books. its gotten me here so far. my next step i believe is to adjust the MAF and VE tables...? and to leave the injector sizing at the 60lb calculations...?

    thanks again

  14. #14
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    would going to speed density be better? the way i understand it. for a 7psi DD car SD tune isnt practical. due to lack of good "resolution"?

  15. #15
    Advanced Tuner robbyredneck's Avatar
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    uh yeah . your gonna want to go sd. your going to be pissed when you peg the maf on day 1 because 7 psi will get boring real fast. GET TO KNOW YOUR SCANNER. set up your ve error tables and don't put the stock data in with the 60's. and while we are on that make sure you have the right data for your 60's. most are rated at 3bar of fuel pressure.not the 4 your running. post up your tune if you would.
    04 6.0 silvy china turbo
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  16. #16
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    Would I peg this Slp Maf? At only 7psi?

  17. #17
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    ..... what does that mean? 512 and 12,000 Hz = 7psi?

  18. #18
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    Quote Originally Posted by MonzterMtrSprt View Post
    ..... what does that mean? 512 and 12,000 Hz = 7psi?
    512/gsec and 12,000 Hz is the max numbers hard coded in the file.
    C.u saying that after surpassing 7psi you will surpass those limits.

  19. #19
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    Messing with your Injector Timing can reduce the raw fuel smell at idle. lots of info to search for.

  20. #20
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    ok so i have messed with the injector timing and offset. i will load that tune when i get home and see what happens. ill post the tune and someone please look at it and if im doing something wrong thanks