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Thread: Terminator X very lean off throttle.

  1. #1

    Default Terminator X very lean off throttle.

    Turbo 5.3L LSx, stock everything except, Cam & Injectors, and TH400 with 3200 stall. At running temp IAC reads 5% in neutral. When driving IAC is 40%. Mostly when I'm driving down the highway (50-75 MPH, 2450 RPM & up), or if I'm cruising on the street (30-45, 1650 RPM & up) and I let off the throttle, the IAC stays at 40% for a couple seconds then drops to 0%, and the AFR goes anywhere between 20 & 30 until the RPM gets down below 1450ish then the AFR will correct itself to around 14. I understand that the AFR should go lean for a second when letting off the throttle, but on the highway it will hang in the 20s and lean pop out of the exhaust sometimes for 30 seconds plus. Any ideas where I should be looking? Can the VE table be that far off in the deceleration portion of the table? Thanks for the help. If I need to load my tune let me know. I'm doing this on my phone right now.
    Last edited by LSx Skylark; 08-20-2019 at 10:10 PM.

  2. #2
    Join Date
    Dec 2009


    Quote Originally Posted by LSx Skylark View Post
    Can the VE table be that far off in the deceleration portion of the table?
    Record & review a Datalog of this occurrence. Also, see if the Decel Fuel Cutoff is enabled.

    Originally Posted by Danny Cabral
    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). (Holley EFI Datalogger Instructions) (Datalog & System Log Information - Read "NOTES") (How To Record & Email A Datalog) (How To Record A System Log & Diagnose A No-Start Condition) (Closed Loop Datalog Tuning - Posts #2, #4 & #6)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, 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.

  3. #3
    Join Date
    Nov 2014
    Ont. Canada


    When in deceleration mode the Closed Loop is turned off, so it will never Learn that part of the table. Try raising your Minimum Injector Opening Time.

  4. #4
    Join Date
    Feb 2017
    St Chuck, MO, USA


    I've been able to pin down that one of my biggest issues is the IAC on my Holly Terminator. Specifically, this is on a 400 Poncho, three pedal Trans Am and when I let off the throttle in gear (TPS 0% like coasting to a stop or slower cruising) the IAC moves from parked to dead closed (IAC 0%) causing the engine to go lean and buck like a mule (very lean) until you apply a little throttle (TPS >0% and IAC resets).

    I've covered the IAC hole with tape, disabled the Idle Spark control and dialed in a hot idle with 20° advance of 900+/- 50 RPM, then reset TPS, enabled the Idle Spark & IAC. IAC at idle is 8-15%, spark jumps +/-2-3°, it holds idle and seems happy there. I have attached my Idle settings for reference.
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    Using HP EFI V4, Comp Cams XR276HR Xtreme Energy 224°/230° Hydraulic Roller, Holley Dual Sync and am confident of the install (I've had it apart and back together a lot). If I set the "RPM above Idle to Start Ramp" at 500 RPM, it hangs at about 1500-1700ish. When I set it at 1000 RPM above, it of course starts ramping the IAC (making a lean condition) while you are cruising at say neighborhood/parking lot speed, it goes bad lean in seconds and starts to buck. The cam is not crazy big, but the whole bucking around is undesirable. Thoughts? Want to see a whole datalog?

    EDIT: I realized this is in the wrong forum, reposting in "Terminator/Stealth EFI" with more detail.
    Last edited by Dan Morrison; 08-28-2019 at 10:28 AM.
    "New" 1979 Trans Am, 400 Pontiac, Super T-10, Chassisworks front end, DSE Quadlink rear end, Wilwood 13in discs with Hydratech hyd brake booster, HP TBI EFI, HP Dual Sync, Comp Cams Hydraulic roller, MSD 6AL (6420) & Blaster 2, dual Spall 13" Elec fans, 150amp Alt, Compustar/DroneMobile alarm...and a lot of other new stuff I'm trying to get put together...

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