Fuel injection? Open or Closed loop?

[Robin Lawrence]

I saw this post last year and always meant to respond. I see it's back from the dead!

I prefer closed loop. While I am not very consistent the system has been. I suggest to most racers to use a CTS and IAT modifiers if their engine combination is temperature sensitive. In a street application it can help drivability at various air temps. In the race car not so much.

Our system reacts very quickly to input from the 02 sensors. Probably faster than most of our competitors. Once you have a good base tune the closed loop will chase the target within 1 to 2 percent. Like someone previously stated you can limit the parameters of the amount of correction either up or down in air fuel ratio.

The Holley also has a learn table. It's exists on top of the base fuel table. The learn table retains the correction that the ECU uses to attain the target A/F ratio. This table can be transferred to the base or deleted. It can be left alone as many street cars use this as their "self learning" or "self tuning" function. The latter being very overused in the EFI Market. The learn function is similar to long term learning in early to mid 2000 year cars. It's a great feature to get a map within a few percent of the target. I use it on the dyno and then turn it off after I have a good base map. The system reacts faster when in Closed Loop with the Learn feature turned off.

I have seen many tuners have very radical air temp correction tables. Unless you are running a supercharger where the temps change dramatically during the run I would not spend a ton of time on that.

Robin