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Thread: High Idle On Startup

  1. #1

    Default High Idle On Startup

    So for awhile I was struggling with my car high idling and requiring a restart to fix. After reading that putting zeros in the Minimum IAC Position, I was pleased that fixed my problem. Now I'm struggling with if I turn off my car that's warmed up and wait 2 minutes+ and start it, it idles at about 2000-3000 for 4ish seconds before going down to the set idle. But if I turn the car off and start it again within a minute, it follows what I have set and doesn't high idle for the 4ish seconds. My IAC Parked Position is set at 70 from temps 138°-235°. So I guess my question is, is there anyway to avoid that 4ish seconds of high idle on startup?

  2. #2
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    Enter zero in the first three "Minimum IAC Position" cells.
    Set the "Max TPS for Idle" at least 2 higher than the idle TPS.
    Ensure the idle speed screw is set to achieve an IAC position of around 5-10 counts at hot idle.
    Try decreasing the Cranking Pulse Width, Afterstart Enrichment & Afterstart Decay Rate.
    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

    After multiple days of messing around and following your advice, I've had no luck in getting the car to not high idle, after 2+ minutes of sitting while warm then starting it. Any other suggestions?

  4. #4
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    Which ECU firmware version is it? Which WBO2 sensor kit is it?
    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

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    ECU Version 3.6
    PC Software Version 3.0.7
    I'm running the Holley WBO2 kit.

  6. #6
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    The C950 IAC circuit is very sensitive to electrical interference. Ensure the spark plug wires (or any other high voltage wiring) aren't too close to the IAC motor/wiring.
    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.

  7. #7

    Default

    They're as far away as possible. Today I began messing with the ECU again, and if I put my After Start Enrichment to 100, it actually starts to not high idle. Left it alone for two hours and came back, and it was doing high idle on startup again.

    After messing around for a little longer it's most definitely the IAC, because the computer says it's at where it's supposed to be. If I put my finger over the hole where the IAC takes in air, the car obviously doesn't high idle when it's started. The IAC is also brand new, one month old. Is this something that heat soak could play a role in?

  8. #8
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    Quote Originally Posted by Sneddon View Post
    Is this something that heat soak could play a role in?
    Personally, I've never dealt with an overheated IAC motor that didn't work.
    Try entering zero in only the first or second "Minimum IAC Position" cells.
    Try these IAC PID Terms. Proportional: 22, Integral: 18, Derivative: 32
    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.

  9. #9

    Default

    Turns out the WBO2 was reading 2 points lean, which was causing the car to be rich everywhere including idle/start.

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