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engine won't stop. Throttle valve?
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williamM
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PostPosted: Thu Feb 08, 2018 10:04 am    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

asiab3 wrote:
Wildthings wrote:
New S-boots (the big shoddily repaired S shaped hose) are available if yours take the same as used in later years.


I don't think the '74-only S-boots are available. Apparently the PO didn't either… Laughing

Robbie



if it's just not as tall- will it work with early air cleaner???
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raygreenwood
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PostPosted: Thu Feb 08, 2018 2:26 pm    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

Here is a little more information on the throttle kicker valve. I forgot where I posted this so it took me a while.

https://www.thesamba.com/vw/forum/viewtopic.php?p=8164179&highlight=#8164179

Ray
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vacilador
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PostPosted: Fri Feb 09, 2018 10:28 am    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

Back on the road, now sometimes after driving a bit, when I'm coasting to stop the engine depowers below an ideal idle....

the engine shutters, rumbles and wants to stall out.

I don't allow it to stall, and keep a little bit of my foot on the gas pedal to keep the engine power up, even while braking. (The indicator lights on the dash flash a bit at the lowest engine power.)

To fix this, I assume the idle could be adjusted (no idea how) or
this is related to adjusting the bolt on the "throttle kicker" / deceleration valve. (some idea how to do that)

Thoughts?
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airschooled
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PostPosted: Fri Feb 09, 2018 11:15 am    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

The engine should idle down just fine without the mechanical deceleration valve, or "kicker" valve. (That's a new term for me!)

How judiciously have you checked for vacuum leaks?

Have you ever messed with the CO (mixture) settings on your AFM?

Robbie
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Wildthings
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PostPosted: Fri Feb 09, 2018 11:56 am    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

I am wondering if this is a 411/412 engine that was transplanted into a Federal model verses it being a California model. Additional pictures of the engine might help. Do the various sticker and tags on the rig say its a Federal model or a California model?
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raygreenwood
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PostPosted: Fri Feb 09, 2018 1:37 pm    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

Wildthings wrote:
I am wondering if this is a 411/412 engine that was transplanted into a Federal model verses it being a California model. Additional pictures of the engine might help. Do the various sticker and tags on the rig say its a Federal model or a California model?


Quite possible.....but that throttle kicker part "was" used on some automatic buses. I was surprised to find that out.

You can see the adjusting instructions and pictures in the Haynes #226 Transporter manual 1972-1979.
It is in the supplement section, chapter 13, page 218, 2nd to the last parargraph. They call it "the idle speed regulator".

It has a very specific adjustment and one of the main tell-tale symptoms they list that indicate it is put of adjustment is if the idle speed drops more than 200 rpm when a gear is selected from neutral or park. To me.....that text is vague.

There is a little more detail on adjusting this part in the 411/412 manual....but the specs for idle and pushrod gap are different.

Both texts note that throttle cable and TB plate positively closed and standard idle should be adjusted carefully first. Ray
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vacilador
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PostPosted: Sat Feb 24, 2018 6:28 pm    Post subject: Re: engine won't stop. Throttle valve? (Updated: engine stalls) Reply with quote

As of this morning, now the engine consistently stalls when I take my foot off the gas pedal (whether in park, neutral or drive) the engine depowers, shutters, and stalls.

If I keep RPM's up, the bus can drive but it's risky. (One foot on the gas, one on the brake on the way home from Lowe's earlier today)

Attaching photos of the engine and the placard on the door frame - evidently the bus is a Federal Model.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

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vacilador
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PostPosted: Wed Feb 28, 2018 7:39 pm    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

Thank you guys for all the feedback, appreciate all the guidance. I love learning about this car and working on it!

This afternoon, I adjusted the idle speed regulator plunger. The Haynes manual says the plunger should be set to between 0.5mm and 1.0mm clearance at the intersection of the end of the plunger and the throttle valve shaft.

This sort of works - the idle is now higher than it was and the engine doesn't stall, which does resolve the issue.

There may still be a vacuum issue, a mixture issue perhaps. If there's an easy or systematic way to approach evaluating those systems, I'm all ears.
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KentABQ Premium Member
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PostPosted: Wed Feb 28, 2018 8:49 pm    Post subject: Re: engine won't stop. Throttle valve? Reply with quote

Here's the easiest way I've found to track down vacuum leaks...
https://www.amazon.com/AutoLine-Pro-Automotive-Dia...ke+machine

It requires an air compressor, but will make even the smallest leak easily detected.
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