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Thread: Overheating - IAC Question

  1. #1
    Join Date
    Jul 2019
    Location
    Austin
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    6

    Default Overheating - IAC Question

    I've gone 375 miles since I installed the Sniper. About 150 miles ago I installed the progressive linkage and letting it Learn, it had some early issues that Learning has sorted out and for the most part it runs pretty good now. My issue is since it was installed when I go to an idle my temp climbs pretty quickly to 215° and now that it is over 100°F outside it climbs to 215° to 220°. Before with a carburetor, it ran 183° moving and 190° at an idle. Now driving, it runs 187° to 193° and climbs at idle. Driving the IAC Position is always at a constant 20%, but when I come to an idle it climbs to 60% and the temp climb with it. IAC issue? I hope this makes sense.

  2. #2

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    The 20% when driving is normal, but you need to adjust your IAC for between 2-10% at hot idle. Not really sure if that would affect the temp though. Maybe it’s super lean causing it to heat up?

  3. #3
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,109

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    Yeah, the 20% IAC Position while on the throttle is the IAC Hold Position. See page 23: http://documents.holley.com/techlibrary_199r11259.pdf (Holley Sniper EFI Help Manual - EFI Software, Tuning & Datalogging)
    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

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    What is your idle RPM set to? Seems like the engine would be screaming with a 60% IAC at idle. Did the idle overheat issue start after the progressive linkage install? If so I'm wondering if you're having a fuel balance issue where some of the cylinders are running lean. Another thing to look at is your timing at idle before & after EFI install. Retarding the timing at idle will cause the engine to heat up.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
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    23,109

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    Quote Originally Posted by mfc133 View Post
    Retarding the timing at idle will cause the engine to heat up.
    Yes, insufficient idle timing can definitely cause overheating at lower RPM.
    https://forums.holley.com/showthread...12-Idle-Timing (Related Forum Thread)
    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.

  6. #6
    Join Date
    Jul 2019
    Location
    Austin
    Posts
    6

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    Quote Originally Posted by mfc133 View Post
    What is your idle RPM set to? Seems like the engine would be screaming with a 60% IAC at idle. Did the idle overheat issue start after the progressive linkage install? If so I'm wondering if you're having a fuel balance issue where some of the cylinders are running lean. Another thing to look at is your timing at idle before & after EFI install. Retarding the timing at idle will cause the engine to heat up.
    My Idle is set to 750. I talked to Holley and adjusted the idle screw and now the IAC% runs at about 2%, it moves up & down sometimes 0%, and sometimes 12%, but settles down usually to 2%. I had to go out of town for the weekend after the adjustment, but I did some driving Friday before I left and it seems to have helped with idle temp. I'll check my timing again. By the way, I am running the Holley EFI Dual Sync distributor and Sniper EFI Coil Driver Module.
    Last edited by paulw; 08-12-2019 at 11:16 AM.

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