Kind of basic question but what kind of spring/gear mechanism is behind that throttle body's butterfly flap?

If I want to open that for a smoke test should I just open that manually and put something under the flap so that it's stays open or is there a more sophisticated method for that?
Of course another method is to remove that TB completely but I would like to keep that in place so that possible leak from that TB seal is also possible to detect.

 

You can just put something in there to keep it open , just don’t turn on the power and make sure it’s not something that will fall in

 

You don't list your year so it's hard to say. I can tell you that I my '99 cable throttle car it uses a standard coiled spring on the shaft to the right of the throttle body. I don't know how it works on e-throttle cars.









I just use a piece of wadded up rag for smoke tests but anything soft should work.

 

OP - The TB has a mechanical drive geared with an electric stepper motor metered by a couple of potentiometers.The gears are sturdy enough to move hundreds of thousands of times while still overcoming the significant torsional strength of the closing spring. The issue with using gorilla force on the TB plate is possible damage to the sensor rotor attached to the sector gear at the end of the plate shaft that tells the ECU the TB plate is at the commanded angle.

When I smoke my intake system, I push the butterfly valve at the bottom and wedge a 3/4” silicon stopper.