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Discussion Starter · #1 ·
I was putting on my K&N Intake this weekend and noticed that with the car off the throttle plate is open probably 15 deg. Is this normal??

Thanks in advance.
 

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Discussion Starter · #3 ·
Thanks! Never seen that before.
 

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The Corvette throttle is fly-by-wire. The throttle butterfly is operated by a servo motor that opens/closes as a function of what the PCM tells it to do. The gas pedal talks to the PCM, the PCM talks to the throttle plate. It's all electronic.

This is totally unlike a "normal" car where the throttle is operated mechanically by a wire connected to the gas pedal. In a "normal" car, the throttle has a return spring that pulls it closed when your foot comes off the pedal.

On the Corvette, the throttle probably stays at the position chosen by the PCM when power is removed when shutting off the engine, and when you next energize the circuit at start up, the PCM moves the butterfly to whatever new position it wants it in.

If you shut down with your foot on the gas, you might get the throttle plate to stop in the fully open position.
 

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Discussion Starter · #5 ·
Thank you very much for that explanation. Just never had a electronic TB.

Thanks.
 

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Because of the servo, does that mean it's a bad idea to finger the spring to get the engine to rev when your under the hood?

I would think that forcing the servo wouldn't be a good idea
 

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The throttle off position is set internal to the throttle body. When you turn on the key, the throttle plate is closed and then opened a fixed amount for start (approximately 8 degrees). Once the engine starts, the feedback controls the RPM.
 

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bigbay00 said:
Because of the servo, does that mean it's a bad idea to finger the spring to get the engine to rev when your under the hood?

I would think that forcing the servo wouldn't be a good idea
There is no spring. The servo motor is attached directly to the butterfly pivot. The only way you could force the throttle open would be to remove the air bridge and push the plate with your fingers. Depending on how strong the servo motor is, you might just bend the throttle plate. You could strip gears in the servo motor, too.
 

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RocketSled said:
There is no spring. The servo motor is attached directly to the butterfly pivot. The only way you could force the throttle open would be to remove the air bridge and push the plate with your fingers. Depending on how strong the servo motor is, you might just bend the throttle plate. You could strip gears in the servo motor, too.
Are you sure? When I had mine apart to changeover to the ported unit, I thought there was a spring under the gears that returns the TB to its closed (or almost closed) position. With the engine off, the throttle plate will move quite easily spinning the motor with it.
 

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I recently moved the servo motor from one throttle body to another pushing the throttle plate without the motor in place resulted in a quick return to the close position. I believe there is an internal spring under the gears, see the photo below.

 
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