High Idle (Warm)

[brickster]

I have a new-to-me 1984 automatic with early (two switch) setup, and have been trying to troubleshoot a high idle condition when warmed up.

I initially assumed it could likely be a vacuum leak and/or auxiliary air valve regulator failure, but yesterday I warmed the van up and manually pushed the throttle valve all the way closed (a few mm) and it returned to a normal idle speed.

I have the Bentley, and will refer to that for adjustment steps, but does anyone have any BTDT advice? I will check that both switches are still functioning.

I noticed that there is a return spring from throttle valve to the plenum. Is it possible that it just needs to be replaced with a new spring with stronger force? There is also a good possibility that the throttle valve itself is pretty gummed up, and I am planning to dismantle and clean.

Anything else to look at with respect to the automatic transmission to TV adjustments (inline spring, etc.)?

[jlrftype7]

Things that I've run into with our Double Switch equipped '84 Automatic.
Throttle, clean it, and if needed, oil it if it binds. If it's really worn, you'll need to source a good used one or a rebuilt one. If you have the Bentley Manual, follow the specs for adjusting the closed idle switch, and make sure no one tampered with the set screw that's supposed to be left alone for throttle plate stop. Sometimes people turn it instead of the large idle air bypass screw near it when trying to set idle speeds up....
Make REALLY sure that the relay level on the transmission, that connects to your throttle, is not binding itself. There are a couple of pivot points on the assembly setup that can get sticky, and you need that relay level to operate like 'butta' so both engine and trans are happy.

Make sure the accelerator pedal pivots under the Vanagon are not rusty and binding as well, your cable needs to be free and easy. You should have a plastic cover over the bottom of the pedal, held on with 4 tiny screws, if it and the screws are still there..... You can spray lube on the cable as it enters its sleeve/casing, and also the underside of the pedal assembly.
I have a new Accelerator Cable installed that I fed ATF down through the entire cable before installing it[ on advice of Ray Greenwood for very long lasting lubing of the cable]
However, with your cable installed, you really only get to attack and lube what you can reach, so plan on hitting what you can, every little bit helps.
Lube or oil the pivot bushing at the throttle arm as well[the one the spring and cable go through, ]

While I doubt your vacuum advance plate is sticking based on your posted notes, it doesn't hurt to lightly oil it either, so you avoid that issue[ I've seen it on other European Cars/Vehicles where a rusty plate started binding once the engine got fully hot]
Remove your distributor rotor and added a bit of light oil to the felt type pad that should be under the rotor, on top of the shaft. I do this every 2 two years now as a maint. item when performing a tune up.

Return Spring tension, I'd do all of the above before I worried about a new spring, a binding throttle or worn throttle alone will not be corrected by a higher tension spring.
_________________
'68 Westy- my first VW and vehicle/Bus- long gone.- sold it to a traveling Swiss couple....
'67 Type 3 Fastback, my 2nd car- gone
'69 Semi-Auto Stick Shift Beetle-gone
2017 MINI Coopers, our current DDs
‘84 Tin Top - Hilga....Auto

[brickster]

[jlrftype7]

Adding pictures of a rebuilt Throttle in case something on yours jumps out as not to spec or out of whack[ highly technical term.... ]

_________________
'68 Westy- my first VW and vehicle/Bus- long gone.- sold it to a traveling Swiss couple....
'67 Type 3 Fastback, my 2nd car- gone
'69 Semi-Auto Stick Shift Beetle-gone
2017 MINI Coopers, our current DDs
‘84 Tin Top - Hilga....Auto

[brickster]

Mine looks just like that except with 37 years of benign neglect. Yours looks great!

I'm planning to replace all fuel & vacuum hoses and the TB gasket (on back order) once I have all of the pieces together to start the job.

I did notice that my accelerator cable boot is completely disintegrated, so it's likely original. Until I can replace, I'll lube and tweak to see what I can do.