Not sure what this thing is near the throttle.

[bytes311]

Hey guys,

Does anyone know what this is? It has a metal flap and two contacts, but it appears to be missing something. Any ideas?

Thanks.

[vwdmc16]

That is your full throttle enrichment microswitch, it tells the lambda system that you are at full throttle and it's sets your frequency valve to a preset frequency to change your fuel pressure in the fuel distributor so the car runs rich which is what you need for maximum acceleration. It is complete you are not missing anything.

[bytes311]

Thank you for your quick response. The reason I thought it was missing something was because the flap isn't always pressed against the contacts. It just sits there. Good to know it's complete!

[hmcelraft]

The car is an automatic - automatics have two switches stacked like that. One is lambda enrichment for full throttle and the other is for transmission kick-down at full throttle. A 5 speed has just one of those switches - the Lambda enrichment.

What you are missing is the rain cover for the throttle mechanism. Those switches are prone to stick open or closed which can play possible havoc with the Lambda and auto shifting.

[Lightning]

Just FYI, the metal flap isn't to create a circuit between them, both metal buttons are switches. The metal flap allows for pushing both switches in.

[bytes311]

Good to know. Thanks!

[Timebender]

Just FYI, the metal flap isn't to create a circuit between them, both metal buttons are switches. The metal flap allows for pushing both switches in.

Can it get anymore high-tech than that? Wow...

[Lightning]

Can it get anymore high-tech than that? Wow...

In all honesty, when I first got my car I believed it was connecting the two metal buttons. The plastic casing had changed shape over time so the buttons wouldn't press in. It wasn't until I unbolted them that I realized they were normal switches. Bolted them back on without over tightening and shifted them so that it lined up nicely and worked as it was meant to.

[DMCMW Dave]

You should check the switches with an ohm meter sometime. One provides a crude full throttle enrichment (bypasses the O2 sensor) and the other is the kickdown switch for the auto trans (manual cars won't have the second switch)

Honestly if they are open (as if disconnected - infinite ohms) you may never notice as the impact is pretty subtle, but if they are stuck closed (close to zero ohms) you'll never get your CO adjustment right and/or the automatic trans will tend to shift "late".

If either of those switched has failed closed it's better to leave it disconnected until it's replaced.

[bytes311]

Thanks for the tip, Dave. I will look into that tonight.