# 70 Formula 400 Sniper EFI issue



## MattDipiet1 (Jan 14, 2021)

I’ve got a 70 Formula 400 (actually 463) that’s had a sniper EFI on it for over a year and can’t get it to run more then 10-15min before it starts choking out and stalling. All readings drop out on the data monitor. I’ve taken live snapshots to report back to Holley and nothing seems to work they’ve suggested. Fuel pressure is ok etc... Any ideas of who I can just take this thing to in New England and have it fixed? Any info would be Greatly appreciated!


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## GTO44 (Apr 11, 2016)

What is your cold IAC% and what is it when it dies out?

You should take a data log of when it happens so we can take a look at the all the numbers.


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## MattDipiet1 (Jan 14, 2021)

I will for sure see if I can get that info tomorrow, thanks for the reply!!


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## GTO44 (Apr 11, 2016)

MattDipiet1 said:


> I will for sure see if I can get that info tomorrow, thanks for the reply!!


No problem. The reason for the IAC is to control the air coming in at idle when the throttle blades are closed. As the engine warms up the IAC starts to close down as it doesnt need as much air. If your idle throttle stop screw is not adjusted properly the IAC % can be out of whack and wont perform its job correctly. At that point the engine isnt getting the right amount of idle air and can can die out.

There are a lot of modifiers for cold start. Thats when your car seems to run ok. By 160 degrees all the modifiers have been ramped out and your at the final values of the tune setup. As long as adaptive learning is active it wont be the fuel table causing it to die. And it souldnt be timing related. Which leads us to the IAC. There are also serveral ways in which to adjust the operation of the IAC, ie. IAC Parked position, IAC ramp decay, IAC hold position, IAC ramp start, IAC startup hold time, sIAC start up decay time.

There are more adjustments that can be made if you’re using timing control as well.


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