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Thread: Increase Engine RPM In Gear

  1. #1

    Default Increase Engine RPM In Gear

    Hello. I have a Dominator ECU, and using two 1200 CFM throttle bodies on a blown Chevy small block. The transmission is a 4L80E with 3500 stall. When I put it in gear, the RPM drops too low 750-800 RPM. I need to increase RPM to 950-975. While in gear and parking brake on, along with front wheel chocked, can I adjust idle screw to achieve this? Also, I will preform TPS Autoset when completed. Any info will be helpful. Thanks.

  2. #2
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    Use the Advanced Tables to create an IAC Offset, or an Idle RPM Offset, or both.
    You will need to wire up a switch of some sort to tell it when it's in gear.
    Most shifters will provide a way to add a neutral safety switch, in which case,
    you can add that into the ECU, and that will tell it when it's in Park or Neutral.
    Effectively, you have it increase RPM or IAC when the Park/Neutral signal is disabled.

    Another option for a gear position switch is a standard PRNDL Switch for a 4L80E/4L60E.
    They provide a way to send voltage or a ground through them, and then you can send that over to the ECU for shifter position.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  3. #3
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    Quote Originally Posted by Udongate56 View Post
    While in gear and parking brake on, along with front wheel chocked, can I adjust idle screw to achieve this? Also, I will preform TPS Autoset when completed.
    The idle speed screw/IAC Position relationship should be done in neutral and at hot idle. Also ensure this isn't tuning related. On the Base Fuel Table, the "in gear" idle area is just above the "neutral" idle area. The "neutral" idle area may be tuned, but the "in gear" idle area may not be. Look at where the live cursor moves to, when you shift the transmission into gear. Is this "in gear" idle area, a little more rich (lbs/hr), than the "neutral" idle area? You'll have to look at the Learn Table too, since they function as one (LINK). Also, ensure the Target A/F Ratio Table and Base Timing Table are flat in these two idle areas.
    http://forums.holley.com/showthread....2523#post62523 (Holley EFI Tuning Tips & Information)
    http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read This!)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  4. #4
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    Quote Originally Posted by Danny Cabral View Post
    The idle speed screw/IAC Position relationship should be done in neutral and at idle. Also ensure this isn't tuning related.
    Actually, it's not necessarily a bad idea to adjust the throttle so that it idles at 0%-5% IAC while in gear, and then to allow the spark PID to bring down the idle while in Park & Neutral. It's actually the only way you can do it with a car that has no IAC. It does mean that it may idle higher in Park & Neutral, but it does guarantee that you have enough air all the time for while the vehicle is in gear. And some cars need quite an extraordinary amount of extra air while in gear, compared to Park/Neutral (usually signs of a converter that is broken/faulty, or that's not correct for your setup).
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  5. #5

    Default

    Another way if the tune is correct, you can use the IAC Kick, have it bring the rpm up a % while in gear. But you will need a wire from the shifter to tell the ECU your in gear.

  6. #6
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    Quote Originally Posted by procharged67 View Post
    Another way if the tune is correct, you can use the IAC Kick, have it bring the rpm up a % while in gear. But you will need a wire from the shifter to tell the ECU your in gear.
    IAC Kick is only momentary to allow the IAC to catch up from a sudden change in engine load. Once the initial kick has happened, it does nothing to help after that.
    -Scott
    Don't forget to check out progress on my Race Car:
    Project Blasphemy - 8.07 @ 171
    Low 8 Second Street Car

  7. #7
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    Exactly, it's only momentary, and a common misconception.
    http://forums.holley.com/showthread....6904#post76904 (Additional IAC Kick/High Idle Information)
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

  8. #8

    Default

    Thanks for the input on that. Tech mentioned this to be used here in this type of issue, but I never tried it. However, I've had the problem with low idle in gear, and after playing with the VE Table, I was able to see that it was lean, adjust the table and it's better than perfect now. I bet his problem is the same.

    Danny showed me how to use the datalog (LINK), and man, it took tuning to the next level.

  9. #9
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    Quote Originally Posted by procharged67 View Post
    However, I've had the problem with low idle in gear, and after playing with the VE Table, I was able to see that it was lean, adjust the table and it's better than perfect now. I bet his problem is the same.
    This is why I mentioned the tuning aspect in post #3.

    Danny showed me how to use the datalog (LINK), and man, it took tuning to the next level.
    You're welcome, and glad to hear it.
    May God's grace bless you in the Lord Jesus Christ.

    '78 BRONCO: 508" stroker, TFS heads, 11:1 comp ratio, Dominator MPFI & DIS, cold air induction, Spal dual 12" fans/aluminum radiator, dual 3" exhaust/Magnaflow mufflers, Moroso vacuum pump, Accusump, engine oil & trans fluid coolers, 100HP progressive dry direct-port NOS, A/C, LenTech Strip Terminator wide-ratio AOD/2500 RPM converter, 3:1 Atlas II, modified Dana 44/60-lockers-4.10s, hydroboost/4-disc brakes, ram-assist/heim joint steering, Cage long radius arms, traction bars, 4" Skyjacker lift, 35" mud tires

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