unknown emission thing

[dlb]

i noticed this thing on the automatic '87 T4 i'm working on right now and have no idea what it is. no mention of it in the FSM. it appears to work similarly to the throttle positioner in that it acts on the same part of the throttle as the TP and is activated by a vacuum diaphragm, which is hooked up to manifold vac. the difference is that the vacuum first runs through something that resembles the VSV from the fuel evap system. so the sequence is

manifold vac --> VSV-type thing --> diaphragm --> linkage --> throttle

here, i'm pointing to the diaphragm and linkage.



another shot of the diaphragm and linkage. you can see the 10 mm bolt/flat blade nut that can be adjusted, but to what end?



here is the VSV-style thing.



any ideas?

[john]

I'm looking in my Chilton manuel and can't be sure, but is it called the Secondary Throttle Diaphragm?
john

[rer233]

think it kicks the throttle open a little more when the ac's engaged??

[dlb]

think it kicks the throttle open a little more when the ac's engaged??

that could make sense. the car had AC until i ripped it out. i'll plug the stuff and remove it later if it runs ok like that.

[ARCHINSTL]

dlb - look at the second diagram on https://tercel4wd.com/forums/viewtopic.php?f=7&t=2810; It's for the USA Fed cars, but it's the same for yours.
Also check the FSM's section on Ac - as rer323 wrote.
Of course it's irrelevant, as you removed your system - as did I.
Tom M.

[tercel4wdrules]

That is the AC idle up. It shows up in the underhood emissions sticker as well I believe.

[Petros]

as noted, it is not for emissions, but rather to speed up idle when you have the A/C engaged. remove it and all the related stuff, will not harm a thing, it serves no other function.