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Thread: IAC Letting Air in Always

  1. #1
    Join Date
    May 2018
    Location
    Dublin, OH
    Posts
    49

    Angry IAC Letting Air in Always

    Hello, I'm having trouble with my IAC motor. I have a 1991 Mustang 347 stroker, with the Holley HP EFI system. I have an IAC motor from an LS1 IROC-Z Camaro. We have the IAC housing converter as well, but it seems to be always letting air in even when the IAC reads 0% on the Holley V4 EFI software.

    The software reads 0% for the IAC.
    I can put my finger over the IAC inlet to block flow and stall the car.
    You can hear it sucking air.
    This is making cold starts very hard up here in Ohio.
    Is it possible I mounted it wrong?
    Has anybody else had this problem before?
    I removed the IAC from the housing and changed its position in the software and saw it moving up and down with the changes I made.
    Any help is appreciated! Thanks.

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,893

    Default

    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

    Default

    I had the same issue and found that the LS wiring harness and Holley throttle body I used had different pin-outs. Switch two wires and now it's fine. When the ECU was commanding 0% IAC the valve was full open.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,893

    Default

    http://forums.holley.com/showthread....neral-IAC-Info (Scroll down to "IAC Motor Harness Connector PIN-OUTS".)
    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.

  5. #5

  6. #6
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,893

    Default

    Fastmanefi, I included your IAC information in my IAC LINK.
    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.

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