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General IAC Info & Ford PWM IAC Wiring

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  • General IAC Info & Ford PWM IAC Wiring

    IAC NOTES:
    1) Adjust the idle speed screw on throttle body, to achieve an IAC Position of about 5% at hot idle.
    Remember to perform another TPS Autoset, whenever you adjust the idle speed screw on the throttle body.
    In the Idle ICF, the "Target Idle Speed (RPM)" must be programmed to the desired RPM speed at hot idle.
    Ensure the proper type of Advanced Idle Control is selected in Idle Settings. "Slow" may provide the best idle quality.
    FYI: Some throttle bodies require a 10% IAC Position at hot idle, to compensate for increased airflow due to further thermal expansion.

    2) Opening the throttle blades (idle speed screw "in"), decreases the IAC Position at hot idle.
    Closing the throttle blades (idle speed screw "out"), increases the IAC Position at hot idle.
    If the idle speed screw is unscrewed too far, the engine is inhaling air from an additional source - vacuum leak.
    Blocking off the entire throttle body amplifies the vacuum leak, and it usually makes a detectable hissing sound.
    Terminator TBI users may need to also adjust the secondary shaft screw (LINK), so the throttle blades are equally open.
    The Commander 950 EFI system uses IAC Position Counts, not IAC Position %, so don't try copying the Commander 950 IAC values.
    IAC motors have an IAC position range of either 0-255 counts or 0%-100% IAC Position (each 1% is the equivalent of 2.55 counts).

    3) Ensure the IAC Hold Position isn't set too high. At particularly low TPS Positions, this can induce more air (> 1% TPS) than some engines need.
    Ensure the TPS Position always returns to 0% at hot idle. If not, it activates the IAC Hold Position and raises the idle speed, causing issues.
    You may have to slightly back-off the idle speed screw (after a TPS Autoset), so the TPS Position always returns to 0% (V3 improved this).
    Ensure your throttle linkage moves/returns freely (hot & cold), and usually a stronger throttle return spring is all that's necessary to rectify this.
    Over-advanced ignition timing, rich AFR and/or primary throttle blades open too far at idle (idle speed screw) can hinder the return to idle RPM.
    Also, if the IAC Hold Position is set too high, or the RPM Above Idle To Start Ramp is set too low, the engine RPM will hang & not return to idle:
    http://forums.holley.com/showthread....8236#post48236 (Read sentences highlighted in red.)

    4) You can test the IAC motor function by changing the IAC Parked Position % (cycle the ignition key off/on
    after each change), turn key-on/engine-off, unplug the wire connector, remove it from the throttle body,
    and verify the pintle position (or just look down the IAC passage in throttle body). Try this at 0% & 100%.
    https://forums.holley.com/showthread...344#post235344 (Related IAC Testing)

    5) If blocking off the IAC air inlet port results in improved idle/deceleration operation, then problem is IAC related.
    If the ECU is commanding 100% IAC Position, it's because the IAC valve isn't increasing the engine speed.
    Ensure the fuel injectors or spark plug wires (or any other high voltage wiring) aren't too close to the IAC motor/wiring.
    The IAC motor is easily susceptible to electrical interference, and it'll cause strange occurrences and become inoperable.
    To eliminate the IAC valve as a problem, temporarily block off the IAC air inlet port with a strong piece of tape.

    6) * Initial Baseline Idle Speed Screw Setting *
    Sometimes the throttle blades are so far off adjustment, turning the idle speed screw triggers the IAC Hold Position.
    If this happens, the throttle blades will require a baseline setting without the IAC valve altering this adjustment.
    This must be accomplished with the engine at hot idle. Be careful of dangerous fan and belt driven components.
    With the air filter previously removed, block off the IAC air inlet port with your finger or a strong piece of tape.
    While temporarily ignoring the IAC Position, adjust the idle speed screw to the Target Idle Speed RPM (in Idle ICF).
    Turn engine off (remove tape). With the key-on/engine-off, perform a TPS Autoset. Cycle key off & restart engine.
    Now only a minute adjustment will be required to achieve an IAC Position of about 5%. Perform a final TPS Autoset.

    7) Sniper EFI Idle Setting/Throttle Blade Setting (Holley Sniper EFI Quick Start Manual):
    Once the engine is up to operating temperature, the idle speed can be set to what was configured in the Wizard.
    To do this, open up the Initial Startup gauge screen that was used in section 17.0. With the vehicle in neutral,
    adjust the idle screw until the IAC Position reads between 2 & 10%. While adjusting the idle speed screw, if the
    TPS Position begins to read higher than 0%, cycling the ignition switch will recalibrate the TPS back to zero.
    NOTE: Do not attempt to set the Target Idle Speed and IAC Position until the engine is above 160°F!
    http://documents.holley.com/199r11193.pdf (Holley Sniper EFI Quick Start Manual - "Idle Setting/Throttle Plate Setting", Page 11)
    https://forums.holley.com/showthread...-Idle-Solution! (Sniper EFI High Idle Thread)

    8) 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.

    9) Typical IAC Control/Ramp Down Parameter Settings
    Advanced Idle Control: ......................... Slow (Usually the best control.) Sniper EFI users select "Sniper TBI".
    IAC Type: .......................................... Stepper (4-wire), PWM (2-wire)
    IAC Hold Position: ................................ 10%-30% (Manual transmissions require the higher percentage.)
    Ramp Decay Time: ............................... 1.0-3.0 sec (Usually 2.0 sec.)
    RPM Above Idle To Start Ramp: .............. 1000 RPM (Or higher.)
    RPM Above Idle To Re-enable Idle Control: 50-200 RPM (This setting can be finicky.)
    Startup IAC Position - Hold & Decay Time: 1.0-1.5 seconds (Less is typically better than more.)
    Not IAC, but Idle Spark control usually works well at: 30-40 P Term & 50-60 D Term.
    http://forums.holley.com/showthread....neral-IAC-Info (General IAC Information - Read "IAC NOTES")
    http://forums.holley.com/showthread....ents-Read-This (Initial Checks & Adjustments - Read Step #3!)
    Scroll down to "IAC Motor" under "Other 5.0L Fox Body Mustang Sensor/Actuator/Hardware Notes":
    https://forums.holley.com/showthread...464#post100464 (Related Ford 5.0L Fox Mustang - Holley HP/Dominator EFI Installation)

    10) With a 2-wire Ford PWM IAC motor, you don't use any of the four existing IAC wires/connector.
    In the software (Idle ICF), select "PWM" as the IAC Type.
    In the Inputs/Outputs screen (Idle ICF), select "PWM+" as the Output Type.
    Then "Pin Map" this new output to an available pin/connector. (See "View Outputs".)
    Now you'll only need to run one wire to the IAC, and simply ground the other wire.
    (If "PWM−" is chosen, then two wires need to be run to the IAC; keyed 12V & ECU PWM− output.)
    https://forums.holley.com/showthread...4621#post54621 (Related Forum Post)

    11) If your throttle body accepts a Ford IAC motor, you may want to use it.
    The Ford IAC is supposedly faster, greater airflow and more expensive (for a reason).
    FYI: A radical camshaft could cause an inoperative Ford IAC valve due to a severe lack of engine vacuum (LINK).
    http://www.rockauto.com/catalog/moreinfo.php?pk=663918 (SMP S820 IAC Pigtail Connector - Late Model)
    http://www.rockauto.com/catalog/more...312&cc=1133952 (SMP S663 IAC Pigtail Connector - Early Model)

    12) To connect up to 4 Inputs & Outputs to the EFI main harness, use I/O Auxiliary Harness 558-400.
    Eight Wire I/O Auxiliary Harness Connector Pin-Out (also in the Holley EFI Wiring Manual LINK):
    Pin A...A12...White/Blue (Input #1)
    Pin B...A3...White/Red (Input #2)
    Pin C...A13...White/Black (Input #3)
    Pin D...A4...White/Green (Input #4)
    Pin E...B12...Gray/Yellow (Output #1)
    Pin F...B11...Gray/Red (Output #2)
    Pin G...B10...Gray/Black (Output #3)
    Pin H...B3...Gray/Green (Output #4)
    http://documents.holley.com/199r10516.pdf (Holley 558-400 I/O Auxiliary Harness Instructions)

    13) Terminator & HP EFI users (Ford engines), may still want to use the preexisting 4-wire IAC harness (Chrysler/GM IAC motors).
    This is because these ECUs only have 4 Inputs & 4 Outputs, so some users can't afford to lose one for a Ford PWM 2-wire IAC motor.
    In this case, it makes more sense to use the Chrysler/GM IAC motor that the harness is already wired for.
    Also, some aftermarket throttle bodies are machined for use with a Chrysler/GM type IAC motor.

    14) Electrically, the Holley ECU can drive two GM/Chrysler stepper type IAC motors.
    There's no additional channel/output involved. Simply splice each wire to the second IAC motor.
    https://www.yellowbullet.com/forum/s...11&postcount=5 (Similar post by Doug F. - Chief Holley EFI Engineer)

    15) The flat 4-pin IAC connector terminals are Delphi Metri-Pack 150/150.2 "pull-to-seat" connectors/terminals.
    The Delphi Metri-Pack 150.2 terminals have a flag for the slotted style connectors (LINK).
    Click image for larger version

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    http://whiteproducts.com/metripack-faqs.shtml (Scroll down for description.)
    http://www.repairconnector.com/produ...Connector.html (IAC Repair Connector Pigtail)
    http://www.powerandsignal.com/docs/D...%20Catalog.pdf (Delphi Connection Systems Catalog - page 2.22)

    16) Holley's HP EFI ECU & Harness Kits for LSx engines will obviously retain the flat 4-pin GM IAC motor.
    Holley's Universal EFI & TBI systems use a flat 4-pin Chrysler IAC motor, which looks identical to a GM unit but pinned differently.
    NOTE: Using a Holley/Chrysler IAC motor (in an Accufab IAC Adapter LINK or GM IAC valve), requires slightly elongating
    one of the two Holley/Chrysler IAC motor mounting holes (toward the center) with a Dremel tool for screw alignment:
    https://forums.holley.com/showthread...9323#post99323 (Related Forum Post)
    http://www.holley.com/543-105.asp (Holley/Chrysler 2-bolt flange type.)

    http://www.holley.com/543-34.asp (Holley/GM 2-bolt flange type.)

    Other Holley EFI systems, such as the Stealth Ram/TPI, use a threaded IAC motor with a square connector:
    http://www.holley.com/543-2.asp (Holley/TPI screw-in type.)
    http://www.holley.com/508-8.asp (Gasket)
    http://www.repairconnector.com/ (Connector)

    IAC Motors: Standard Motor Products AC416 (TBI, MPFI & Terminator), AC16 (Stealth Ram), AC234 (GM LSx)

    17) IAC Motor Harness Connector PIN-OUTS:
    Holley (Chrysler) IAC stepper motor pin-out with flat connector:
    Use a magnifying glass to see the four IAC connector cavities - designated A, B, C, D.
    These letters are located where the wire seal retainer clips to the connector body.
    The four wires are A: purple/blue "A LO", B: purple/black "B HI", C: purple/white "B LO", D: purple/yellow "A HI".
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual - page 31)

    General Motors (LS, LT, etc.) IAC stepper motor pin-out with flat connector:
    Use a magnifying glass to see the four IAC connector cavities - designated A, B, C, D.
    These letters are located where the wire seal retainer clips to the connector body.
    The four wires are A: purple/white "B LO", B: purple/black "B HI", C: purple/blue "A LO", D: purple/yellow "A HI".
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual - page 37)

    GM Screw-In (threaded) IAC stepper motor pin-out with square connector (Stealth Ram/TPI):
    Use a magnifying glass to see the four IAC connector cavities - designated A, B, C, D.
    These letters are located where the wire seal retainer clips to the connector body (C & D behind retainer).
    The four wires are A: purple/yellow "A HI", B: purple/blue "A LO", C: purple/black "B HI", D: purple/white "B LO".
    http://documents.holley.com/techlibr...10555rev17.pdf (Holley EFI Wiring Manual - page 39)
    http://forums.holley.com/showthread....y-HP-Dominator (Early harness wiring error.)

    Four IAC wires at the ECU P1B connector (same for all 4-wire IAC stepper motors):
    Pin B1
    - purple/blue - "A LO"
    Pin B2
    - purple/yellow - "A HI"
    Pin B8
    - purple/white - "B LO"
    Pin B9
    - purple/black - "B HI"
    http://www.fastmanefi.com/holley-tech (Determining Which IAC Motor - Scroll down to "IAC Wiring Considerations".)
    https://youtu.be/6dfigDyUUw4 (Fastmanefi.com IAC Connector Video)


    18) The predefined Advanced Idle Control parameter values are listed in the Help Contents (Tuning/Idle Settings, click "F1").
    However, the Slow, Medium & Fast selections aren't listed, so I posted those PID & Blanking values first.
    SLOW - IAC Idle Control:
    Main P = 6 ..... IAC Blanking Window = 30 ....... Low Side P = 7
    Main I = 8 ...... D Blanking Window = 40 ......... Low Side I = 11
    Main D = 45 ... Low Side Enabling RPM = 100 ... Low Side D = 60

    MEDIUM - IAC Idle Control:
    Main P = 18 ... IAC Blanking Window = 40 ....... Low Side P = 30
    Main I = 32 .... D Blanking Window = 40 .......... Low Side I = 50
    Main D = 60 ... Low Side Enabling RPM = 100 ... Low Side D = 60

    FAST - IAC Idle Control:
    Main P = 36 ... IAC Blanking Window = 40 ....... Low Side P = 50
    Main I = 64 .... D Blanking Window = 40 .......... Low Side I = 89
    Main D = 60 ... Low Side Enabling RPM = 100 ... Low Side D = 80

    Holley 4BBL TBI - IAC Idle Control:
    Main P = 18 .... IAC Blanking Window = 40 ....... Low Side P = 30
    Main I = 32 ..... D Blanking Window = 40 ......... Low Side I = 50
    Main D = 60 ... Low Side Enabling RPM = 100 ... Low Side D = 60

    Holley 4BBL MPFI - IAC Idle Control:
    Main P = 16 ... IAC Blanking Window = 40 ....... Low Side P = 30
    Main I = 32 .... D Blanking Window = 40 .......... Low Side I = 50
    Main D = 60 ... Low Side Enabling RPM = 100 ... Low Side D = 60

    GM LSx - IAC Idle Control:
    Main P = 18 ... IAC Blanking Window = 25 ....... Low Side P = 25
    Main I = 32 .... D Blanking Window = 40 .......... Low Side I = 40
    Main D = 60 ... Low Side Enabling RPM = 100 ... Low Side D = 60

    GM DBW - IAC Idle Control:
    Main P = 6 ..... IAC Blanking Window = 30 ....... Low Side P = 7
    Main I = 8 ...... D Blanking Window = 40 ......... Low Side I = 11
    Main D = 45 ... Low Side Enabling RPM = 100 ... Low Side D = 60

    5.0L Ford - IAC Idle Control:
    Main P = 4 ..... IAC Blanking Window = 40 ....... Low Side P = 5
    Main I = 14 .... D Blanking Window = 40 .......... Low Side I = 17
    Main D = 80 ... Low Side Enabling RPM = 100 ... Low Side D = 80

    19) PID Definitions:
    P Term – (Proportional) The speed/gain of the system when there's a large deviation in the
    target idle speed. Raising this value increases the speed at which the IAC moves in order to
    remove target idle speed error. If this value is too high for a specific application, the IAC Position
    will oscillate (be out of control) and cause the engine speed to surge up & down. If the value is
    too low for a specific application, the IAC will be slow to react to quick changes in idle speed
    deviation. However, it's much better for this Term to be conservatively slow, rather than too fast.
    The Proportional Term makes a change based on how far the engine is from the setpoint. For
    example, if the desired idle is 750, the IAC would move more if the actual engine speed was 600
    than if it was 700. The size of the Proportional Term determines how far the IAC moves.

    I Term – (Integral) The speed of the system when the engine speed is near the target idle
    speed. Raising this value increases the speed at which the IAC moves when the engine speed is
    close to target idle speed. If this value is too high for a specific application, there may be "too
    much IAC activity" around the target idle speed. If the value is too low for a specific application,
    the IAC will be slow to react to changes near target idle speed. However, it's much better for
    this Term to be conservatively slow, rather than too fast. The Integral Term acts to eliminate the
    steady state error. The Integral Term job is to get the engine to idle at exactly 750 RPM (or
    whatever the Target Idle Speed RPM is) and not at 740 or 760 RPM, for example.

    D Term – (Derivative) Higher Derivative terms reduce the tendency of idle speed overshoot.
    Smaller Derivative terms slow down the IAC movement as target idle speed is approached. The
    Derivative Term looks at where the engine is going and where it will be in a half of a second. It
    doesn’t look at where the engine is right now. For example, if the
    Target Idle Speed RPM is 750
    and the engine speed is 700, but it's rapidly approaching 750, the Derivative Term will try to
    close the IAC to slow the idle down and keep it from "overshooting" the
    Target Idle Speed RPM.

    Click image for larger version

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    Attached Files
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

  • #2
    In reading this thread on wiring a Ford IAC, it mentioned the difference between a Chrysler and a GM IAC.
    I recall from a long time back that I should be able to test an IAC to determine which one I may have. I have an old throttle body, and I don't recall which IAC it uses.

    Can I just check continuity or resistance between the pins to determine which one I have?
    For example, if I find continuity across pins A and D, then I should have the Chrysler unit. If I have continuity across A and B, then I have the GM unit.
    Is this correct? Appreciate the help.

    Comment


    • #3
      Originally posted by carbuff View Post
      Can I just check continuity or resistance between the pins to determine which one I have?
      For example, if I find continuity across pins A and D, then I should have the Chrysler unit. If I have continuity across A and B, then I have the GM unit.
      Yes, an Ohms continuity test will identify the two stepper motor coil windings; then refer to the wiring schematics.
      May God's grace bless you in the Lord Jesus Christ.
      '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

      Comment


      • #4
        Is there a screw in IAC with the flat connector? I have a Wilson TB with the Holley HP and don't want to use an output for the IAC. The Wilson TB uses a Ford style IAC. I have the FAST adapter (307022) which converts to a screw in type IAC. All of the screw in IACs have the square plugs. Thanks.
        '83 Chevy C10, 383, BW S475, TKO 600
        Installing a Holley HP

        Comment


        • #5
          Originally posted by Wild83C10 View Post
          Is there a screw in IAC with the flat connector?
          I've never seen one, and I don't know if it exists.
          The Weather-Pack connectors/terminals are easy to use,
          so I'd cut the flat connector off and install the square connector:
          http://www.repairconnector.com/produ...njection-.html
          May God's grace bless you in the Lord Jesus Christ.
          '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

          Comment


          • #6
            Does the PWM+ output only supply voltage when the engine is running? I have my IAC assigned to J1-B12 and cycled the key forward which primed my fuel pump but I never received any voltage out of that pin.
            93 Notchback, 383ci SBF, Highports, 80mm turbo, custom cam, TH400

            Comment


            • #7
              Originally posted by Rick90lx View Post
              Does the PWM+ output only supply voltage when the engine is running?
              I would imagine so. You wouldn't need/want the IAC motor powered with the key-on/engine-off.
              May God's grace bless you in the Lord Jesus Christ.
              '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

              Comment


              • #8
                I was curious because I'm metering things as I go before making final connections. The reason I ask is because I had my IAC assigned to J1-B12 and I wasn't getting 12 volts there. What I found out this morning is that my Fluke 77 wasn't responding to the voltage changes fast enough. I hooked up my Power Probe 3 and was able to see the voltage fluctuate very quickly. I then checked J1-B11 for voltage and there was none. I reassigned the IAC to that pin, sent it to the ECM and cycled the key. I now have the same voltage fluctuation on that pin. Apparently that is normal, so I'll go ahead and solder up my connections. Thanks again.
                Last edited by Rick90lx; 06-15-2013, 01:47 PM.
                93 Notchback, 383ci SBF, Highports, 80mm turbo, custom cam, TH400

                Comment


                • #9
                  Originally posted by Rick90lx View Post
                  I hooked up my Power Probe 3 and was able to see the voltage fluctuate very quickly.
                  Yes, most conventional multimeters can only measure Duty Cycle (%) and Frequency (Hz), which is all you really need to verify anyway.
                  To view the actual PWM (pulse width modulation) waveform (sine or square wave), a multimeter with an oscilloscope function is required.
                  May God's grace bless you in the Lord Jesus Christ.
                  '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

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                  • #10
                    Does the Ford IAC care which of the 2 wires is the PWM+?

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                    • #11
                      Originally posted by kbscobravert View Post
                      Does the Ford IAC care which of the 2 wires is the PWM+?
                      Yes, some have a built-in diode clamp to prevent reverse polarity. Look for the small "+" & "−" symbols on the connector.
                      May God's grace bless you in the Lord Jesus Christ.
                      '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

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                      • #12
                        I'm having a little problem trying to figure out which is the positive and which is the negative. I'm using the Mass-Flo EFI and it has the early version of the IAC motors that you showed in the opening post. I ordered a replacement connector from Standard, but the part isn't marked which terminal is which. Could someone tell me which one is which?

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                        • #13
                          Originally posted by [email protected] View Post
                          I'm having a little problem trying to figure out which is the positive and which is the negative.
                          I don't know because I don't use that type of IAC motor. But can't you figure it out from the prior Mass-Flo wiring?
                          May God's grace bless you in the Lord Jesus Christ.
                          '92 Ford Mustang GT: 385"/6.3L SBF, Dart SHP 8.2 block, forged steel crankshaft & H-beam rods, forged pistons, Trick Flow Twisted Wedge 11R 205 CNC Comp Ported heads, 12:1 compression ratio, 232°-244° duration/.623" lift/114° LSA camshaft, TFS R-Series FTI Comp Ported intake, BBK 80mm throttle body, Holley Dominator MPFI & DIS, Holley 36-1 crank trigger, MSD 1x cam sync, PA PMGR starter, PA 200A 3G alternator, Optima 34/78 Red battery, 100HP progressive dry direct-port NOS, R134a A/C, Spal Dual 12" HP 3168 CFM fans, Frostbite 3-core aluminum radiator, Pypes dual 2.5" exhaust, off-road X-pipe, shorty headers, Earl's -6AN fuel system plumbing, Walbro 255 LPH in-tank pump & Pro-M -6AN hanger, S&W subframe connectors, BMR upper & lower torque box reinforcements, LenTech Strip Terminator wide-ratio Ford AOD, 10" 3000 RPM C6 billet converter, B&M Hammer shifter, Stifflers transmission crossmember & driveshaft safety loop, FPP aluminum driveshaft, FPP 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 M/T Street Comp tires.

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                          • #14
                            I will have to dig out the manuals and look for the wiring diagram. Hopefully it shows some sort of detail.
                            I think I found it. Scroll down, the connector is shown open end, and the locking tab is visible.


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                            • #15
                              From the diagram, it looks like the pin next to the locking clip on the plug, is key on +12V, and the ground is what is controlled by the ECU. That changes things.
                              Last edited by kbscobravert; 11-10-2014, 05:56 PM.

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