Throttle Position Switch

[aguabonita]

Hey all,
First off, I did Search quite a bit, so please don't flame me. I even found Terry K's post a couple of years ago stating that this topic seems to come up once every week or two. I haven't seen it around for a while so I thought i'd do my part to up the average.

Having idle issues. New GW 2.2 motor installed 6 mos ago (around 6k on it now). Was revving like crazy when cold (sometimes up to 4k rpm), surging, hunting, etc. Local mechanic adjusted TPS and it worked like a charm. That was two months ago. The idle prob is now back which seems weird as I don't know how that thing could get out of wack that quickly. (Maybe I need a new throttle body?) Now it is low revving to the point of stalling when coming to a relatively quick stop (though every once in a while it will high rev too, especially when cold). I have learned to turn off the motor for a minute after the engine is warm. The probs disappear after restart and it idles nicely.

On a side note, when I do start up the van cold it make a squeal noise for a second (sounds like a belt). I don't know if that is related or just coincidental.

Anyways, I would like to learn how to adjust the TPS myself as this seems like a common issue in Vanagons. My questions are the following:

1) Could someone send me a link or post detailed instructions outlining this procedure?
2) What tools will I need? I gather from DogPilot's post a while ago that I need an allen wrench. What else? Is there some feeler gauge or something to measure the gap mentioned in the Bentley.
3) It would be really neato if someone outlined how these things work so that numbskulls/newbies like me could integrate it into their VW mental workings.

Pretend like you are teaching a eighth grader (minus the hormone surges) how to do this. Be kind, gentle, yet firm.

Kevin
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'87 Westfalia, GW 2.2, and some other goodies
'90 Volvo 245

[McVanagon]

Of those two Allen heads, one of them loosens the switch (Red Cricle), and the other (Yellow Circle) has a adjuster cam in it. When you turn the adjuster head it moves the switch in and out of adjustment. (white arrow is pointing towards the front of the car)

If your throttle body is worn (like mine) you might not be able to use the recommended gap. I adjust it by feel. I want to hear the switch ‘click’ at the slightest opening of the throttle, then ‘unclick’ when it returns. With the worn throttle body, you’ll have to increase the gap so it will be able to click back on it’s own……

So, with the (car off) switch loose, stick an allen wrench in the adjuster screw, and start opening and closing the throttle with your hand, adjusting the switch until it ‘clicks’ with the slightest turn, but still ‘unclicks’ with the return spring’s tension. It is that ‘unclick’ at the closed position that gives you your idle.

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'69 Mike
'85 GL
'87 Wolfsburg Hardtop

[brooklynvanagon]

Hint pretend they are made of a delicate pot metal, ready to shear off if your are more than delicate with them. Consider that it's easier to remove the entire throttle assmb.

[OilNBolts]

And if you do remove the throttle body, be prepared to replace the gasket.

[VanagOnly]

Also the plastic cam does wear out making it unable to stay in adjustment.I have to adjust mine way too much.Have a new switch just need the time to install it.
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87 Wolfie
Past rides:72 Bus- RIP
72 Volvo 145 wagon-RIP
76 Jeep Wagoneer-RIP
67 Bug Dad's Daily-Project

[Terry Kay]

<<Local mechanic adjusted TPS and it worked like a charm. That was two months ago. The idle prob is now back which seems weird as I don't know how that thing could get out of wack that quickly. >>


Kevin,

Sounds like a simple problem.

The operating cam is worn beyond it keeping a consistant adjustment.

Replace it, & the retaining washer, and you should be good to go for some time.

Any time the TPS is outa wack, the throttle body should be removed and the switch arm & operating cam should be inspected for wear, as should the throttle body bore & plate.

The throttle shaft should be inspected for excessive wear also.
If it's not tight in the bushings It'll wobble and create a problem in the TPS operation.

These are the most popular things to consider when setting up the TPS correctly.
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T.K.

[volkswagatron]

is this the same tecnique as a 1.9 tps adjustment mine looks like this?

[McVanagon]

[volkswagatron]

she is in deed an 85 gl...doesnt the digifant get vanagon syndrome as well.i was told never to look for that on an 85?

[volkswagatron]

so do you need to have the ignition at the on position just not engine running?so the switch will have power.or do you do this with everything off.????

[RGS Paul]

This sounds more like an idle control module issue then a TPS issue, the hunting idle and ability to 'fix' it with a restart are telltales. Have you checked the operation of the TPS with a multimeter? Lots easier then adjusting it just to find out it was ok.

Paul
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'87 Syncro 7-Pass. Adventure Touring Vehicle
"Simplicate, then add lightness." Colin Chapman

[Terry Kay]

Paul,

The wandering idle issue, and the all of a sudden shutting down is usually the TPS switch adjustment or the cam is just worn out and not able to move the switch at the right time OR--the switch is is shot itself.

Hope that the switch isn't DOA,a and still functioning.

There isn't any more of them anywhere, and this may be a problem.

And this is all only if the Van is a late model digijet 85 with a single trottle postioning switch.
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T.K.

[volkswagatron]

i believe it is,because its the same switch.i took it off last night.its pretty grungy and i couldnt hear it click at all,the cam was fine but not moving the lever enough to push the button very good so i adjusted that.but like i said it looks pretty dirty id say its original for sure.i am going to try to find one,sucks they are few and far between.

[Terry Kay]

If the cover is missing off the bottom of the switch--this probably the reason the switch has gotten filthy.
But--the switch having an accumluation of some dirt on the outside won't usually prevent it from operating.
If it's done, it's done.

No, they aren't far & few in between.
There isn't any available new from VW.
It's a discontinued parts--NONE.

Contact the Van-Cafe, and talk to Peter or Chris.
They might have a fix for you

They had a guy making a switch repair--but you have to send them your switch plate.

Try that if the switch is shot.
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T.K.

[ccisco]

IIf you do need a new one...What TK said about Van-Cafe, and also check out Tencent's classified. I think he's developed an alternative....Ben, of Benplace may have some used throttle bodies/switches. Also, you may want to hit some wrecking yards, you may find one that could be cleaned up a bit... The list of critical parts that are NLA is getting larger and larger.
Charles

[chimivee]

The Van-Cafe switches are available:

http://www.van-cafe.com/home/van/page_1224_305/throttle_switch_1985_through_1991.html
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-James
86 Syncro Westy, etc

[volkswagatron]

hey thanks chimvee,thats a good price as well,i just recently heard of van-cafe.as i am new with these f@#$in vanagons,love it to death though.

[BulliBill]

Hi all,

Are these the switches you are talking about, or are these earlier air cooled Type 4 FI switches, or are they something else entirely?

They have different part numbers. One is 021 906 028 and the other is 055 906 028. Can anyone shed light on the differences? The only visible difference I can see is that the terminal positions are slightly different (the "021" is on the left and the "055" is on the right). I found a few of each in my stash and wonder if I'll need 'em for my '87 Digifant FI Westy or if I should make them available to someone who does need 'em.

Thanks for any clarifications!

Bill
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I'm looking for these license plate frames for my fleet:
Coeur D'Alene - Lake Shore Volkswagen
Mission VW - San Fernando
Thornton VW - Stockton

Thanks for any help!

[Terry Kay]

They look like early TPS switches.
One is low speed, the other is high speed.

They won't work in your 87 Vanagon where you only have a single switch that does both low & high speed operations.

Take a look at the picture of the Van Cafe's switch Fix---

One single switch for any late 85 to 91 Vanagon Throttle Body.
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T.K.

[syncrodoka]

Those won't do any good for your '87. They are for the older DJ motors and possibly the aircooled ones.