Throttle Valve Switch Question

[Sobeys]

In reading this post: http://www.thesamba.com/vw/forum/viewtopic.php?t=268356&highlight=tps+switch (McVanagon Reply) there is an indication that at full throttle an ohm meter would read infinity.

Bentley (24.5 states "switch must display continuity only during idle and full throttle position of throttle valve switch" This would lead me to believe an ohm meter would read 0 at full throttle.

Is there a second switching point at full throttle?
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Dave
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87 Vanagon Westfalia

[tencentlife]

No, it's the same switch closing twice, at CFC and WFO.
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Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[Sobeys]

Not sure what CFC and WFO is

Should I be able to hear the switch close at full throttle?
_________________
Dave
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87 Vanagon Westfalia

[tencentlife]

Completely F'in Closed and Wide F'in Open.




(they fall for it every time.....)




Yes, you should hear the switch click at idle and at full throttle.
_________________
Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/

Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[syncrodoka]

If you can't get it to work get out the BFH- big f'n hammer.

[Perales]

[Sobeys]

OK... can't hear swich at WFO. Is there an adjustment I can make?
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Dave
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87 Vanagon Westfalia

[Perales]

Read Dogpilot's post on this thread.
http://www.thesamba.com/vw/forum/viewtopic.php?t=298058&highlight=tps
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-- 1987 Westfalia automatic (Captain Vino)

[tencentlife]

[Perales]

[240Gordy]

[Terry Kay]

<<can't hear anything at WOT>>

You won't be able to hear the switch going onto the cam--just coming off of the cam's ramp at low speed.

Adjust / replace the cam & retaining washer.
The cam is plastic and will wear out, once or twice every 100,000 miles or so.
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T.K.

[tencentlife]

Click, click, click-click-click! (apologies to the Specials).

Put an ohmmeter on it.
_________________
Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/

Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[Terry Kay]

The second "click" is incoincendental.
The TPS is has an initial set up procedure using the first cam lobe only--
The switch set up is done at, and on the firt lobe, the vacuum reading and ohm meter reading is taken on the first lobe of the operating cam.

If everything is set up right the second lobes high speed WFO operation will automaticly be correct---

If, and only if, the second lobe on the cam isn't worn out and not closing the switch at the right time all will be good.

8 times outa 10 the plastic cam is worn out and not allowing the switch to function properly.

It's wear item.
the other 2 times outa 10 it's the switch---it's worn out from doing the click-click maringa every time your foot hits the accelerator.

Try adjusting the switch first with the eccentric.
If it's a no go, and you can't get to the proper TPS adjustment specs, first replace the cam, and see if your there-- if no, then the switch .
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T.K.

[iceneweb]

[teej]

Ok, WBX university continues for this Digifant beginner.

In working on the idle, I discovered the TPS is not closing at WFO. First I checked by ear, heard no click at full throttle, so I got out the multimeter to double check. Switch tests closed by click and continuity check at idle position, switch not closed by both listening and then verifying infinite resistance at full open.

So what? What does this mean in terms of engine running? I suspect it has been this way for a longish time. Is this an "urgent fix" or just an "important fix" or even a "when I get to it" item?
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1986+ Wolfsburg Weekender Pop-Top 2.3 WBX Manual Trans

[Baxta]

On my Corrado, which has the same fuel management software (digi-1) the WOT switch activates fuel enrichment. This I believe is more important on the forced induction engine because bad things happen if you run short on fuel in boost.

So I guess the answer is 'how fast do you want to get there - RFN, pretty soon (both unlikely using a WBX but that's another (all the other?) thread...) or sometime this week?'

Good luck!
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Greg
'87 Syncro Westy 'Bastian'
2.2l

[tencentlife]

The WFO response on this system isn't very prompt. I've watched it on a wideband and it can take 30 seconds before the ECU goes open-loop. It isn't a programmed amount of enrichment per se, it just tells the ECU to go open-loop so the AFM has a direct influence on mixture, the rest of the time it's closed-loop and the O2 sensor lambda system effectively overrides the AFM, to keep the air/fuel ratio close to 14.7:1 so the catalyst will work.

So not having the WFO switch closure is one of the least worrisome things that could be wrong with your Digifant. It's not as if there's even a noticeable power response when it does work, but that does depend on the AFM settings. If you drive the van heavily loaded or up a lot of long grades the WFO response might help keep pinging at bay by eventually resulting in some enrichment, once again that depends on the state of tune of the engine and fuel used, these engines are very detonation-resistant and can withstand a lot of abuse under high load.
_________________
Shop for unique Vanagon accessories at the Vanistan shop:
https://intrepidoverland.com/vanistan/

Please don't PM here, I will not reply.

Experience is kryptonite to doctrine.

[teej]

Thanks for the replies, exactly the type of explanation I was hoping for. We generally run premium, maybe not necessary but was advised it a good idea, and have driven some pretty mountainous country so far while heavily loaded. Sluggish, yes, but no knocking or pinging at all while under full throttle. Perhaps the higher octane is compensating for the faulty WOT switch response, and/or these are tough little engines. I like ours.

I think I know which list to put this fix on, thanks all.
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1986+ Wolfsburg Weekender Pop-Top 2.3 WBX Manual Trans

[Terry Kay]

If you can't here that switch coming off of the low speed cam , or the high speed the ECU doesn't ave a clue waht postion that throttle plate is in at any given time.

That's the basic plan for the TPS to give the ECU the correct throttle postion readings.

Now, if you plan on overriding the basic engineering plan dialed in by the krauts--i think your going to have some lean or real rich thottle issues and poorer than normal engine performace & fuel economy.
If you can live with that-forget about that switch--it'll run--like shit---
But it's running up to your expectations--so leave the switch & cam alone.
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T.K.