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Thread: Idle Tuning - Helpful Info Inside

  1. #11
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    Cool stuff!
    Old numbers with 422 Iron Block
    10.84 @ 124 MPH, 1.57 60\'
    549 RWHP / 757 RWTQ
    I'd rather be blown ... AND stroked!
    Now: 441 CID (Corevette 427) , ATI Procharger D-1SC Supercharger

  2. #12
    Lifetime Member Bruce Melton's Avatar
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    I would love it if we could expand this as many of us are converting to 90mm TBs and likely large cams which with ETC, is a whole new game.

    2000 C5 Coupe, 6M, Callies/Mahle stroked LS7 (441), Blackwing, Halltech, LS3 intake, 90mm Shaner TB, ported L92 heads, FAST 50# inj, not too much cam, Kooks 1 7/8" headers , 3" catless mid pipes, Z TIs, track suspension, , 3:90 rear, EFI V2, LM-2, etc.
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  3. #13
    Lifetime Member SSpdDmon's Avatar
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    Quote Originally Posted by Bruce Melton
    I would love it if we could expand this as many of us are converting to 90mm TBs and likely large cams which with ETC, is a whole new game.
    The basics should still be the same.

    **get the Desired Idle Airflow right with the RAFIG process
    **timing should generally fall in the 24~32* range at idle for aftermarket cams (timing should be slightly more for auto's in gear vs. P/N)
    **increase the delay timers for the IAC learning and direct airflow control
    **work the throttle cracker/follower settings - I've recently noticed the throttle follower works better on my cam when I increased the airflow values (50% for the first 3.55% and 25% for the rest of the table) and increase the decay rates slightly so the revs won't hang on the way down. My throttle cracker settings are pretty much the same as when I created this post. Keep in mind though, the follower works a little differently on f-bodies vs. C5's. IIRC, I don't think the C5's used the follower multiplier table like the f-bodies do (ie C5 values are all 1's vs the f-bodies range of 1-3). So, there are some instances where an f-body will multiply it's throttle follower airflow values by 3 whereas the C5 is a direct pull from the airflow table. I'll check into this more later....

  4. #14
    Lifetime Member Bruce Melton's Avatar
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    So far>
    Seems with 90mm TB at least using stock .0255 and trying .0330 also .0157 as B4349, my stock desired airflow (B4307) is 7.3 G/S @80C and the logged RAFIG is < 1. So desired is ~7x actual, how to move it up?
    The engine just dies when it reaches 178* when warming up. This coincides with going into closed loop.
    I know I need more air but is "desiring" more in B4307 going to do it?

    2000 C5 Coupe, 6M, Callies/Mahle stroked LS7 (441), Blackwing, Halltech, LS3 intake, 90mm Shaner TB, ported L92 heads, FAST 50# inj, not too much cam, Kooks 1 7/8" headers , 3" catless mid pipes, Z TIs, track suspension, , 3:90 rear, EFI V2, LM-2, etc.
    PowrMax Performance

    100 mm PowrMAF

    LM-2 EFILIve package with TAQ -sLM2 V-2 serial cable> Package deals

  5. #15
    Lifetime Member SSpdDmon's Avatar
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    Desired Idle Airflow is the lookup table. As the ECT's change, the PCM looks to this table for the base idle airflow requirement (like it looks to the VE for fuel). It opens the elec. throttle body or IAC valve (depending on setup) according to that table. Then based on the idle learning tables and the delta between desired idle rpm and actual rpm, it adjust the TB or IAC through the idle trims. If it's wanting to die on you, I'd point to one of two things: either you're trying to get the car to idle at too low of an RPM for your setup OR the idle and learning tables aren't setup appropriately.

    PM sent...

  6. #16
    Lifetime Member SSpdDmon's Avatar
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    Original post sync'd with current best tune.

  7. #17
    Lifetime Member hquick's Avatar
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    Hi guys,
    I'm in the process of going through the AutoVE on my Whippled 98 (0411 pcm) Burb.
    I logged RAFIG and the numbers are strange...although I don't know what's normal
    Do I need to get the AutoVE out of the way before doing the RAFIG, RAFPN process or can I do it now?
    I have the VE table pretty well dialled in, I believe but the Burb is running extremely rich at idle. I can't figure out why.
    Any advice/help would be greatly appreciated
    Attached Files Attached Files
    Howard

    YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'T
    MOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THE
    DUCT TAPE.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.


    98 K1500 'HOLDEN' Suburban.
    Custom Whipple SC, Mercruiser Marine intake, 0411 PCM, 4L80E w/shift kit

  8. #18
    Lifetime Member SSpdDmon's Avatar
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    Well, running rich is going to affect idle quality. You want to try to get it close to an AFR in the 14's. What size injectors are you running? If they're bigger than 42's, you may have to futz with the injector tables to try and get your minimum pulse widths down.

  9. #19
    Lifetime Member hquick's Avatar
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    Thanks SS,
    at present I'm running the standard 19pph, non-interchangeable injectors.
    I realise OI may run out of fuel up top...but I would think idle should be OK with the stock tables?
    Howard

    YOU ONLY NEED TWO TOOLS IN LIFE - WD-40 AND DUCT TAPE. IF IT DOESN'T
    MOVE AND SHOULD, USE THE WD-40. IF IT SHOULDN'T MOVE AND DOES, USE THE
    DUCT TAPE.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.


    98 K1500 'HOLDEN' Suburban.
    Custom Whipple SC, Mercruiser Marine intake, 0411 PCM, 4L80E w/shift kit

  10. #20
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    AFR at idle is a strange subject. big cams are so inefficient in the idle range they usually cause a fake lean. i've seen some big cams which like to idle richer. one big cam would idle fine at 13.5AFR but would surge at both 13.4 and 13.6. there are no hard rules for it. try things, see what works.

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