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Thread: Idle drops off at start up

  1. #1
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    Idle drops off at start up

    What would cause my idle to drop off at start up? What tables control this? My engine almost dies at start up. I would like for my idle to drop no less than the 750 programmed into the file.
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  2. #2
    Senior Tuner Higgs Boson's Avatar
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    Have you tuned your ETC Idle Angle table? If you have one, I can't see the tune on this computer.

    Made a huge difference in my idle after changing the intake and TB.

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    This table is stock. What values would I change to keep it from closing too much? Increase the 450, 590?
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    Senior Tuner Higgs Boson's Avatar
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    create a scanner graph like the editor table logging throttle angle against lb/min

    do a completely cold start (overnight cold) and fire it up, and don't touch the gas or anything at all, AC off, etc log it while you let it idle in place until it is completely warm and idling at the commanded RPM with the cold start procedure completely finished.

    paste the angles into the editor table.

    make sure your other items are in place like MAF/VE and injector data, otherwise, garbage in / garbage out.....

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    Thanks Higgs! I'll see if I can give that a try.

  6. #6
    Senior Tuner Higgs Boson's Avatar
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    Also, make sure if you have tables for idle per vct angle that you adjusted those accordingly to how you adjusted your regular idle rpm field. I will look at the tune this evening or in the AM.

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    Quote Originally Posted by Higgs Boson View Post
    Also, make sure if you have tables for idle per vct angle that you adjusted those accordingly to how you adjusted your regular idle rpm field. I will look at the tune this evening or in the AM.
    Not sure I follow you on "tables for idle per vct angle". Anyway if you will take a look when you get time I would appreciate it!

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    Here's a short log I ran. Is this what you are looking for?

    The engine died on the first start up. I had to give it throttle to get it running.
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  9. #9
    Senior Tuner Higgs Boson's Avatar
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    I wont be able to see it until the am. What are the results? Screenshot works great. ;-)

    Did it have any effect? Does it idle good or die after you have been driving it around? Is it only on cold start it dies or all starts?

  10. #10
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    Quote Originally Posted by Higgs Boson View Post
    I wont be able to see it until the am. What are the results? Screenshot works great. ;-)

    Did it have any effect? Does it idle good or die after you have been driving it around? Is it only on cold start it dies or all starts?
    Not sure I have the correct PIDs in my config. Here's a screen shot of what I logged. Did not find a PID labeled Air Mass lb/min.
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  11. #11
    Senior Tuner Higgs Boson's Avatar
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    Third pid mass air flow is airmass in lb/min

    Fuel trims are pulling all kinds of fuel, very rich. Tune the maf, when you first start it it's probably very rich and dying.

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    Yes, I saw how negative the trims were. I'll go in and fix that first. Like you say maybe the problem. Thanks Higgs!

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    Quote Originally Posted by Higgs Boson View Post
    Third pid mass air flow is airmass in lb/min

    Fuel trims are pulling all kinds of fuel, very rich. Tune the maf, when you first start it it's probably very rich and dying.
    Leaning idle has really helped. I haven't driven the car to dial it in perfectly yet but so far with a much lower idle the engine does not die. Thank you so much for the help. Had no idea the LTFTs had this much effect on idle.

  14. #14
    Senior Tuner Higgs Boson's Avatar
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    my pleasure

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    Quote Originally Posted by Higgs Boson View Post
    my pleasure
    Your the man! Drove the car today. Started with no drop off in rpm at start up. Tweaked it a bit more and idle start up is perfect now. Was able to drop rpm even more and start up. Would have never gotten there without tuning the MAF. Thanks again!