Page 1 of 4 123 ... LastLast
Results 1 to 10 of 40

Thread: General IAC Info & Ford PWM IAC Wiring

  1. #1
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    17,623

    Default General IAC Info & Ford PWM IAC Wiring

    IAC NOTES:
    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, due to increased airflow caused by further thermal expansion.

    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.
    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).

    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 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.)

    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%.

    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 spark plug wires (or any other high voltage wiring) aren't too close to the IAC motor/wiring.
    To eliminate the IAC valve as a problem, temporarily block off the IAC air inlet port with a strong piece of tape.

    * 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.

    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)

    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.

    Typical IAC Control/Ramp Down Parameter Settings
    Advanced Idle Control: ......................... Slow (Usually the best control.)
    IAC Type: .......................................... Stepper (4-wire), PWM (2-wire)
    IAC Hold Position: ................................ 10%-30%
    Ramp Decay Time: ............................... 1.0-3.0 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.)
    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")


    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 Inputs/Outputs (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)

    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.
    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)

    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)

    Avenger & 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 & Outputs, so some users can't afford to lose one for a Ford 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.

    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.
    http://www.yellowbullet.com/forum/sh...11&postcount=5 (Similar post by Doug F.)


    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. 

Name:	Pull-to-Seat-Illustration.jpg 
Views:	14370 
Size:	83.5 KB 
ID:	476
    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)


    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 Chrysler IAC motor in a GM IAC valve requires one of the mounting holes just needs to be slightly elongated 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.)
    Click image for larger version. 

Name:	543-34_01.jpg 
Views:	341 
Size:	25.0 KB 
ID:	3187
    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)

    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".)
    Click image for larger version. 

Name:	82c417_2df442fc9c074f95bd1d5eae036c3c2f~mv2.jpg 
Views:	535 
Size:	68.3 KB 
ID:	3168

    Click image for larger version. 

Name:	HolleyECUs_zpsbd8866f7.jpg 
Views:	13986 
Size:	74.7 KB 
ID:	575
    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

  2. #2

    Default

    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.

  3. #3
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    17,623

    Default

    Quote 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.

    '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

    Default

    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.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    17,623

    Default

    Quote 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.

    '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

  6. #6
    Join Date
    Aug 2012
    Location
    Dayton, OH
    Posts
    307

    Default

    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.

  7. #7
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    17,623

    Default

    Quote 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.

    '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
    Join Date
    Aug 2012
    Location
    Dayton, OH
    Posts
    307

    Default

    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 at 12:47 PM.

  9. #9
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    17,623

    Default

    Quote 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.

    '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

  10. #10

    Default

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

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