Holly HP EFI-- Idle & IAC Tuning

[Signman]

Originally Posted by Robin Lawrence

Not really any issue. Chevrolet Performance did just that during testing on the COPO's in 2013 and 2014. I believe they had worked on the cylinder to cylinder on the dyno so it was fairly well matched.

Using the Holley to perform closed loop in the primary allows you to enable closed loop at a lower RPM. The optimum A/F ratio will probably be slightly richer than in the collector. Optimum A/F is relative so it will need to be tested to determine the best for a particular combination.

Robin

Thank You for that Robin.
Been saying the same years.
People have asked me what AFR I run. Usually turn the conversation to asking where their O2 sensor is located and why optimum AFR may be different due to location if simultaneously recorded. Then go on to explain how fresh air is sucked into the collector. At low RPM fresh air influences the sensor even when located in the primary tube.
Not always easy to wrap your head around this stuff but once understood opens a lot of doors of understanding.