[JLMounce]

Originally Posted by HWYSTR455

Or the throttle blades are hanging up. Is the throttle return spring too weak? Is the throttle cable hanging? If it's not fully closed when you turn the key on it will use whatever position it's at as 0% (TPS autoset occurs at every key-on)

If the IAC AND the TPS are at zero, sounds to me that the throttle blades aren't closing all the way, and it's referencing the open position as 0%. Maybe take the throttle body off and check to see if there's any witness marks on the gasket etc, and that they are near closed.
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Any exhaust leaks?



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Good call on the throttle hanging up. My system did the same thing when my throttle cable started binding in its sheath.

[Formulajones]

On the holley it's pretty common to have the rear blades hang up. Sometimes after they are run a while and go through some heat cycles things move around. Sometimes it's apparent right away.

It's an easy fix. You can have a look at the blades and make sure they are centered but most just give the rear throttle blade spring another wrap around the shaft.

https://youtu.be/avRqQZBOxP0

[TransAm400]

Interesting. I'll check out the secondaries first. I also have an extra IAC on hand I can swap out if needed.