I know it's been rumored that some teams are using the current rule to take control of idle speed control systems. Most idle speed controls are setup with some kind of variable valve that routes additional air around the throttle blade at idle to allow electronic control to stabilize the idle speed during varying load situations and during cold warm up. The rumor is that teams are using the open box rule to pin these valves open to serve as an alternate route for additional air to enter the engine. This makes more power. Here's what's important. This could be accomplished with a simple jumper inside the stock box (gray area legal?) and isn't the direct result of an EMS change. It would also be possible if we speced an EMS and harness to have the harness shipped from the manufacturer with just enough leads to only allow interface between the ECU and the needed sensors and needed outputs. No PWM outputs for things such as idle control valves that would be used for an unintended purpose. I suspect this is where GA Cup is going with their spec ECU/harness rule. Want to eliminate this? Require all idle speed control systems be removed and any holes left in the intake blanked if an alternate EMS is used. Idle speed control is not required for a race engine where cold start is of little concern and there is not an a/c compressor continually cycling. In fact, probably 90% of the street cars that I do installs on do not utilize any form of idle control with their aftermarket EMS. They cold start and idle just fine.
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1) Sure you can bypass the throttle but all the air still has to flow through the air meter and snorkle. On my car I couldn't tell a bit of difference with that valve open or closed. Seat of the pants dyno and logging of MAP agreed - nothing. The restriction is downstream of the throttle.
2) I like the idle control valve on my race car. Much less hassle warmup and more consistent idle.
3) I don't see anywhere in the current rules where having the ECU operate signals that the stock harness brings to it is even remotely illegal. No gray in my reading of it. The only exception I see is traction control.
4) I don't like the idea of a spec ECU. Write the rules to nail the issues and use any brand that conforms.