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Thread: Help with vehicle staying running and cold starts without throttle aid...

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  1. #1
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    Unhappy Help with vehicle staying running and cold starts without throttle aid...

    I cannot for the life of me, get my vehicle's tune correct so that it will start on it own without giving it gas on cold starts. It will start without help once warmed up though.

    And also after a complete cold start the vehicle will not stay running after gear changes. Idles fine in park at first, then put it into reverse...after about a second it starts dropping rpms then stall saves, then dies. Restart, same thing happens again until I can give it enough gas to stay going for a while. But if it isn't warmed up enough before the next complete stop it will die again.

    Then if it isn't completely warmed up but not completely cold its a 50/50 shot that it acts this way.

    I've been through all the normal idle threads and tutorials and just can't get these 2 situations tuned out.

    I have the right desired air flow, IAC counts, etc.

    I am posting my tune below, and help would be GREATLY appreciated.

    Thanks

    Jeremy

    Current Tune:
    PNtoD_CL6_LingMAF_PortedTBSS_Fast.ctz

  2. #2
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    You probably won't wan't to hear this but the usual procedure is to get your VE & MAF dialled in fairly accurately before you get your idle and low speed driveability right. Looking at your VE table and MAF cure they are just not looking very clever currently. I believe they may need a lot more work to smooth them out before you can cure your idle.

    If they aren't correct then you may be chasing your tail trying to cure the other issues. Not very helpful but I tend to look at the VE and MAF tables in any tune to see what your working with.

  3. #3
    Joe (Moderator) joecar's Avatar
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    +1 VE and MAF both need work.

    Post log files showing RAFIG pids.

  4. #4
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    Well im not sure what else I can do for ve and maf, ive done calc.maft plenty of times. I guess I can swap to calc. Vet and do that a bunch of times. But I keep getting the same stuff thats already in my ve and maf tables.

  5. #5
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    You've had this problem since last year. I saw your previous thread on this...

    http://forum.efilive.com/showthread....on-cold-starts

    I've had a look at your tune, and a lot of the tables don't look quite right to me. Do you have a stock tune to start over with?

  6. #6
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    Ive since added more mods and done calc.maf after it because of a new maf sensor and intake manifold/tb and have since modified other tables to try and help with initial startup since then with no luck.

  7. #7
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    Is it worth posting a pic of your inlet setup as it looks like something is causing disruption to the air through the MAF. Do you still have a diffuser before the MAF? You have a ported TB? Not always a good idea that can change the airflow over the IACV port for example and affect the stock tables. The injector table suggests your FPR is vacuum referenced? Just trying to check some basic stuff that affects a lot of the main reference tables.

    It's frustrating as I have a very similar setup 224/226 112 cam with a tadge less lift, mine is manual though. I used the LS1-M6 base tune from one of the tutorials and that's served me well. Only slightly tweaking the throttle cracker/follower tables to suit my Edelbrock 80mm TB.
    Last edited by bimbleuk; April 9th, 2014 at 04:13 AM.

  8. #8
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    Okay. I think you're better off starting over with a stock tune, but if you want to keep using your current tune then try this...
    Set all values in B4105 to 450.
    Set all values above zero IAT in B4205 to 35
    Set B4206 to Disable.
    Add 0.3 to all values in B3701.
    Make sure B4001 is correct for your current injector size.
    then
    Retune your MAF and VE tables.
    then
    Redo RAFIG/RAFPN

    If you find it running too rich or too lean on cold start, then adjust B3632

    And, as warlock007 already pointed out to you in your previous thread, with your cam you should idle a bit higher... especially important for cold starts.
    Last edited by statesman; April 9th, 2014 at 02:43 AM. Reason: Corrected table number

  9. #9
    Joe (Moderator) joecar's Avatar
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    VE:
    after you redo your VE, you must get rid of any sharp steps/drops/spikes/holes...
    large steps/drops/spikes/holes cannot physically exist, so you have to flatten/interpolate these:
    i.e. the un-hit cells have to be brought up or down so that they are close to the hit cells
    --> I'm talking about only minimal smoothing
    ripples of a few percent in one direction are ok) (i.e. not major steps)

    MAF:
    after you redo your MAF, same thing, you have to bring the un-hit cells into the 4th order polynomial curve;
    there is a spreadsheet somewhere on the web to do this, but it can easily be done by hand too;
    i.e. the MAF curve must look like a smooth 4 order polynomial (i.e. its slope keeps increasing);
    the MAF curve has to be quite smooth (this is how the MAF works), but don't use the smoothing tools, do it by hand.

  10. #10
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    I have a Lingenfelter 100mm mass air flow sensor slot style so no it does not have a diffuser any longer I have a 92 millimeter fast throttle body drive by cable and a TrailBlazer SS intake radically ported for the sake manifold

    also the IAT sensor reads off on this computer because I cannot adjust the i-80 scalar so I unweighted the IAT sensor because of this

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