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Thread: Terminator X Idle stability tuning with A/C help.

  1. #1

    Default Terminator X Idle stability tuning with A/C help.

    This system is awesome! I just need a little help on getting that perfect idle stability. It's a 408 stroker with a cam with 228° duration. T56 transmission, Fast intake with Holley 112-589 throttle body, so it has an idle air bypass screw.
    I have the idle set at 850 with the IAC steps stabilizing at 4-6%. With the A/C off, it's consistently stable as much as I can tell, but it's hot out and I've been driving with A/C on for most of the three days that I've had it running. With the A/C on, it's inconsistent for its stability. Most of the time, it's great, but occasionally it'll stall when releasing the clutch when coming to a stop.

    Changes I have made to the tune after the first Wizard start are: IAC STARTUP DECAY TIME reduced by 20% across the whole range due to it running rough initially after startup. I saw the AFR in the 10s-12s then switch to 14s when it started running smooth. The 20% reduction really helped this. When it's cold (65°F right now) it still a bit rich on after start. If it's over 80°F then it starts like expected.

    Next I increased the A/C IAC Kick percentage to 5%. This seemed to reduce the effect of the ac compressor kicking on and the RPM dropping then recovering. I've just increased the IAC RAMP DECAY by .5 to 5.5, but have not test driven it.

    I thought about increasing the IAC HOLD POSITION to 45, but want to test drive the last change before the next. Does anybody have any guidance on this issue?

  2. #2


    I've made more changes. I upped the A/C IAC Kick percentage to 15%. That has made the RPM fluctuation hardly noticeable when the A/C turns on. I also increased the Idle base timing from 12° to 14°. That really seemed to help getting a consistent stable return to idle.

    Now I have one problem, when engine braking with the A/C on, it will usually stall once I release the clutch. I think this is happening from the computer seeing the TPS at 0% and it starts the IAC Ramp Decay Time and closes the IAC to far trying to get RPM to drop. Then when the clutch is released, the IAC is to far closed to catch the engine and it stalls. The only thing that I can think of is keep increasing the A/C IAC Kick percentage. Can anybody tell me if that'll keep the IAC from dropping to low during engine braking with the A/C on?

  3. #3
    Join Date
    Dec 2009


    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.

  4. #4


    Thank you for the link.
    It sounds like a fueling issue. So far I've done all adjustments with the handheld. Sounds like I should use the laptop and Holley EFI software and should be paying attention to the fueling tables during the stalling event. Do I want my A/C IAC Kick wire on the A/C activation wire from the Vintage Air controller, which is a - source, or on the compressor power wire with a relay to change the signal to negative, so the A/C IAC Kick happens when the compressor cycles on?

  5. #5


    Use whichever wire is energized when the A/C clutch engages. If you have vehicle speed as an input, these issues can be tuned out with an Advanced Table. Andrew
    IG @projectgattago

  6. #6


    So it seems to have been able to Learn. I drove the car for four days now without it stalling. I believe it was hitting an area in the Base Fuel Table that has finally Learned. Now, this is a Terminator X. It doesn't have a speed sensor wire. Can it be added?

  7. #7


    Is it the Terminator X or the X Max? It can be added to the Max, but not very easily to the regular Terminator X. Since you you're still tuning, you should Transfer Learn To Base and manually smooth the Fuel Graph. Andrew
    IG @projectgattago

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