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Old 03-29-2022, 03:26 PM
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Default Holley Sniper EFI

Recently , I nstalled the Holley Super Sniper 1250 EFI
My IAC( Idle air control) remains a constant 90- 100% engagement when cold.The engine is a 470 Pontiac with a Sr cam only making 8/10 inches of vacuum at cold idle. AFR is set at 12.8 idle@ 1k rpm. And goes up to 14.5 cruise acceleration, with a 40% IAC default setting. There is no idle or throttle response issues. Just wondering if anyone else is experiencing these issues with large street cams.( 254/262@.050, .582 lift with 1.5 HS. 72* of overlap. And what are your settings?
I'm very new to this EFI stuff and old, so keep it simple guys. Lol

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Old 03-29-2022, 03:55 PM
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Are you saying the IAC counts are 100 when cold and 40 when hot, idling? Or does it actually read in %? There are ways to manipulate the IAC with the throttle adjustment. If you need more opening when cold, then adjust the throttle position to achieve minimal IAC opening when hot. Yes you'll have to recalibrate the tps closed position after making this type adjustment. 12.8 seems a little fat for idle. Just my opinion
ETA yes it's normal to need a lot of idle bypass air(the IAC function) with a cam like that.

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Last edited by Scott65; 03-29-2022 at 03:57 PM. Reason: Addition
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Old 03-29-2022, 04:34 PM
62posbonny 62posbonny is offline
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With the engine fully up to temperature, hot oil and after a good long drive, you will want to set your IAC to between 2-10% at idle per Holley instructions. You will likely get better drivability by not using the IAC to overcompensate for throttle blades being closed too far for your combination at idle. Should be a quick adjustment.

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Old 03-29-2022, 04:37 PM
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I don't have a sniper, but the methodology should be the same.

You want to set your IAC counts at warm idle, in park or neutral. There should be a throttle blade adjuster on the throttle body itself, typically towards the front of the unit, on or near the throttle linkage.

Like the FiTech I believe the Sniper should have a digital stepper motor for the IAC which should display counts from 0-255. I don't believe it's in percentage, but correct me if I'm wrong as I'm a FiTech user.

Your warm idle counts should be around 10. If your counts currently are at around 40 warm, that's not really that far off and if you aren't noticing issues with cold starts, it may be okay as it sits.

I think your Idle AFR is a bit on the rich side. With as large of a cam as you run, it may like mid to upper 14:1 range better. Use your cranking and afterstart fuel to compensate fueling for a cold engine, not your base map.

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Old 03-29-2022, 04:40 PM
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And also timing to help idle QUALITY, but also speed in certain circumstances. Hopefully you are controlling timing with the ecu. That's a game changer

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Old 03-29-2022, 06:17 PM
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Quote:
Originally Posted by Scott65 View Post
And also timing to help idle QUALITY, but also speed in certain circumstances. Hopefully you are controlling timing with the ecu. That's a game changer
This, x1000!

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Old 03-29-2022, 06:40 PM
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68WarDog,

I recently had a Holley Sniper EFI put on a '70 GTO with a 461 CID engine. The cam is definitely smaller than what you have. It is the off the shelf Comp Cam XR 288HR. The Holley replaced a FI-Tech system that was nothing but problems.

I wish I was able to give you more information, but I'm shackled to my desk until April 18th. After that I can provide some video of the read out which might help you out.

In the mean time, I have some video of the engine with open headers and another after I got it back that should provide you with the idle quality. I just don't have the numbers you are looking for

Open Headers:
https://www.youtube.com/shorts/tku6RdlCeiQ

Full exhaust and walk around:
https://www.youtube.com/watch?v=GYMaDAeOO3g&t=126s

I will be having the same Holley system put on my '73 TA with a 496. The cam in the engine is 242/248 @ .050. The Brawler 850 CFM carb will be replaced.


Last edited by napster; 03-29-2022 at 06:50 PM.
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Old 03-30-2022, 12:00 AM
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Quote:
Originally Posted by Scott65 View Post
ETA yes it's normal to need a lot of idle bypass air(the IAC function) with a cam like that.
Thanks, that's the information I needed. Hot idle IAC is 2/4.

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Old 03-30-2022, 12:05 AM
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Yep, have similar cam and 1250 Sniper and have the same behavior with the IAC counts.

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