Page 1 of 4 123 ... LastLast
Results 1 to 10 of 38

Thread: Free Revving

  1. #1

    Default Free Revving

    OK, LS 6.0L, big cam, TB, etc, HP EFI on it. I have it running OK. Idle hunts a little more than I'd like, but I'm working on that. My issue is when I just go to WOT from any throttle position NOT under a load, in neutral or park, the engine revs but seems like it's laboring. In other words, not a quick clean rev. Now that being said, when driving this thing pulls like a freight train. It runs hard & clean with every gear change. It has been this way from day one. I just now remembered it, while moving some IAC settings that were causing the throttle to seem to hang and not dropping as I would like. I'm obviously not any type of expert, but I'm willing to learn! Any ideas? Thanks in advance!
    Last edited by oldskool; 10-15-2017 at 07:37 PM.

  2. #2

    Default

    I would do a datalog and capture the event. The datalog will show you what's going on.

  3. #3
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,157

    Default

    Quote Originally Posted by oldskool View Post
    I just now remembered it, while moving some IAC settings that were causing the throttle to seem to hang and not dropping as I would like.
    http://forums.holley.com/showthread....neral-IAC-Info (General IAC Information - Read "IAC NOTES")
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  4. #4

    Default

    Thanks Danny. I went back & adjusted the idle until the IAC was 3-5% at hot idle, and TPS Autoset. Drove the car, seemed to run good. It was taking away some fuel under moderate throttle at 40-60 MPH (7-12%). Free rev seems the same no different, but then all of the sudden, the idle started hanging high? In gear, if you opened the throttle, it wouldn't idle high, but in neutral it was high after you cracked the throttle. I did datalog a few revs. I feel like I'm moving back not forward, LOL. The datalog was only a few free revs not the high idling. I tried to zip the file, as I can never get anything to load here, LOL. Here's a copy of my tune, feel free to take a look. Thanks.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,157

    Default

    1st, fix the constant MAT sensor "High Error". 2nd, your Base Timing Table needs to be reconfigured, at least in the idle & off idle area (which should be flat - same values in idle cells). 3rd, same problem with the idle area of the Target A/F Ratio table.
    Try increasing the Idle Spark Control P Term to 40. Try changing the IAC Hold Position to 20%, the Ramp Decay Time to 1.0 sec, the RPM Above Idle To Start Ramp to 1200 RPM, and the RPM Above Idle To Re-enable Idle Control to 200 RPM.
    http://forums.holley.com/showthread....e-Tuning-Notes (EFI Idle Tuning Notes)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  6. #6

    Default

    Great! Thanks so much for the reply!!! I'll change the IAC Hold back to 20%. I made the rest of the changes except the Base Timing Table. I want to be clear there; change the timing so it has same values from say 600 to 1000 RPM, then ramp up? Target AFR same change. Thanks for your help. I have the air filter tube off at the moment, waiting on a coupler & elbow. It will be here tomorrow. I had to reroute the intake tract. Again, many thanks.

  7. #7
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,157

    Default

    Quote Originally Posted by oldskool View Post
    I want to be clear there; change the timing so it has same values from say 600 to 1000 RPM, then ramp up?
    Yes, the idle RPM columns and two or three more off idle too. (It doesn't have to be the entire column, it can be just the idle & off idle area of those columns.) This will help the engine return to idle (deceleration).
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  8. #8

    Default

    I would also overlay that datalog on the global File and watch the timing the engine is seeing through that free rev. For the first half of the rev the timing is 14° or less. Going to make it quite lazy. You will have to figure out what's best for your combo, but something to look into.

  9. #9

    Default

    Danny, I read in some of your tuning tips to try a richer idle? Right now I have 15.0 AFR, maybe try a 14.0 or 14.5 to clean up the idle? I'll have to figure out how to overlay the datalog on the Global File first, LOL. Thanks for the info!

  10. #10
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,157

    Default

    Quote Originally Posted by oldskool View Post
    Right now I have 15.0 AFR, maybe try a 14.0 or 14.5 to clean up the idle?
    You tell me how your engine likes to idle. It's user-programmable EFI, you have to experiment with the engine.

    I'll have to figure out how to overlay the datalog on the Global File first, LOL.
    Quick Datalogger Information:
    Always provide data, not just symptoms. Is the AFR & ignition timing optimized? Overlay the datalog onto your Global File.
    Ensure the Target A/F Ratio table is properly programmed for your engine. Ensure the ECU is "Learning" (Learn Table LINK).
    Scroll through the datalog to the problem area. Then look exactly where this happens on the Base Fuel & Timing Tables. Scrutinize:
    RPM, MAP, MAT, TPS, CTS, IAC, Target AFR, AFR Left, CL Comp, Ignition Timing, Duty Cycle, Fuel Flow, Fuel Pressure & Battery.

    Using the Holley EFI software (LINK), look at where the live cursor moves to during this occurrence, and
    manually tune that area of the Base Fuel Table (enrich or lean) & Base Timing Table (optimize ignition timing).

    I find the most helpful datalog function, is overlaying the datalog on your Global File.
    I'm in the habit of using the datalog Overlay feature every time I review a datalog.
    Click on "Datalog" (on the top Toolbar), "Activate Overlay", then "Open Data Log".
    You can literally "playback" a recorded event, and watch it as it happened on any screen.
    Minimize (shrink) the datalog window, and move it to the bottom of any Global File screen.
    Then click & scroll anywhere on the datalog, and watch it playback on your Global File (EFI software).
    http://documents.holley.com/techlibr...9r10543rev.pdf (Holley EFI Datalogger Instructions)
    https://forums.holley.com/showthread...s-amp-Datalogs (Datalog & System Log Information - Read "NOTES")
    https://www.youtube.com/watch?v=iqHO...C6FEA0BB99AF17 (How To Record & Email A Datalog)
    https://forums.holley.com/showthread...7531#post77531 (Closed Loop Datalog Tuning - Posts #2, #4 & #6)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: Dominator MPFI & DIS, A/C, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/X-pipe/shorty headers, 100HP progressive dry direct-port NOS, 160A 3G alternator, Optima Red battery, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

Page 1 of 4 123 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us