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Thread: 7730 tuning help with A1 file

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  1. #1
    Electronic Ignition!
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    7730 tuning help with A1 file

    Hello, needing help on tuning. I have an 88 Fiero GT. 3.4 swap, truleo intake, Sprint headers 17# injectors, mild cam,1.6 roller rockers, fidanza aluminum flywheel, 7730 with DIS. EGR delete,underdrive pulley, heads were ported. It starts and runs. Lots of power. It idles fine when warming up but once it's warm and idle drops the idle surges. Give some throttle and it will die under deceleration. I talked to someone from a local tuning shop and one of the things he said was my light flywheel is probably causing the surging due to the lack of inertia. He suggested turning up the idle. Wandering what you all think about that and if so how do I do that in tuner pro using A1 mask? The guy at the shop said turn the adjustment screw on throttle body, but I was hoping to tell IAC to allow more air if that's possible. Thanks in advance for any and all input.

  2. #2
    Fuel Injected! steveo's Avatar
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    yes you need a bit more idle speed with a light flywheel, what you really want to do is set the target idle speed in the bin a bit higher, but you might find it still surges.

    a datalog will show you if IAC feedback is contributing to it (you'd see the iac counts up and down quite a bit) in which case altering some iac parameters might be necessary, to bring it back to its rpm target more slowly.

    the timing advance at idle is also critical with a light flywheel, you could play with that a bit.

    another trick for engines that persistently stall when you get off the throttle really quickly is to add quite a bit of timing and a bit more fuel in 'stall' range (say under 400 rpm and under 40 map). that way when it's falling off that cliff, the extra fuel and spark will act like a trampoline. it should fall back more gently after that initial boost, by which time the IAC might be able to keep it going. i've used this on engines with static idle (no IAC valve at all)

  3. #3
    Electronic Ignition!
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    That's good info thank you. I'm really ignorant when it comes to tuning though. The way things are labeled in the program I cant seem to figure what to change . They say something vs something. Do you know what scaler to make these adjustments under the A1 mask. For example if my IAC is up and down a lot do I decrease the step size to slow it down? Not in front of a computer right now but I will look at it later and try to figure it out.

  4. #4
    Electronic Ignition!
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    Looking at the data log I do see that the IAC is trying to keep up with idle. down as idle increases and up as idle goes down. Im not seeing any parameter option to slow it down. most options have to do with A/C, TPS and start up temps.

    as for adding timing and fuel, is that going to be done in the idle VE table. also what would be a bit? I wouldn't want to change to much and mess up something.

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  6. #6
    Electronic Ignition!
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    A1_tpv5.xdf

    that should be it. Hope that works

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