TheSamba.com :: View topic - Early 4 pin TVS adjustment and troubleshooting

Tue Jun 12, 2018 10:23 am

Sorry this will seem like an overly long and complicated method.

The gist is this.....

Its not that the books are not correct on how to adjust this sensor. In fact....when the TVS is NEW...and the throttle shaft and throttle plate are NEW...the simplistic book method works probably 95% of the time.

In short the books...none of them...are using 40+ year old parts and do not have any observations or checks to allow verifying ...not just the overall function...but the exact position of each switch part....so you can figure out WHY a TVS may not give you correct function when you use the simple book method of adjustment....and what if anything you can do about it.

One of the biggest failings of the books with reference to D-jet is the damn TVS adjustment. For decades...thousands of owners patiently and carefully follow the Bentley and Elfrinks guide and others and adjust their TVS religiously like the book....and when the car STILL does not function correctly...they figure the TVS is not the issue and move on and chase drivability functions elsewhere forever.

I would have a much better pictorial for this...but I do not any longer own a TVS of this series. :cry:
I think I have a mangled one in a bucket somewhere but...hopefully this will get the point across along with understanding details about where the actual wiper arm contact point is from my other later TVS pictorial.

Ok….the trick to adjusting each type of TVS...when its got some mileage and wear on it..…is knowing exactly what is happening and what it’s supposed to do at each stage of its movement while the throttle is opening.

Right now we are ONLY talking about what I call the early 4 wire TVS….with the four wire soldered plug.

It has two main circuits/switch sets:

A. the idle running circuit and switch…which is NOT enrichment. It’s just basic fuel for idle.

B. The fuel enrichment circuit for during the period of throttle opening movement.
This enrichment does not happen or continue…unless the throttle is in motion. It is essentially…the equivalent of the accelerator pump in a carburetor.

In the red circle with red trace connected to pins #14 and #17 is the “idle”/throttle closed contacts. When these are closed/connected, the switch in the yellow circle will be open. There will only be fuel supplied by the ECU to run basic idle.

In the yellow circle is the enrichment switch that connects to the inside wiper arm or ground track and is ALSO connected to pin #14 as you can see in the white circle and the switch connects it to pins #9 and #20 alternately as the outer wiper arm moves over their tracks. When the throttle moves and the “idle” contacts open/break contact, the enrichment switch connects/makes contact.
Pin # 14 does double duty. It is effectively the ground pin for the wiper/enrichment circuit AND the idle switch/circuit. It should never serve both contacts at one time. One should always be open and one should always be closed depending on throttle position.

This TVS has three functions:

1. At idle, with throttle FULLY closed…it signals the ECU to simply run with no acceleration enrichment because the throttle is closed
That is done when this contact is closed creating the electrical loop between pins #14 and #17.

NOTE: you will notice that in this diagram wire #14 does two things. It provides linkage for both the “common” or ground wiper track and for pin #17. So effectively for the conversation…it acts like a GROUND for both circuits.

2. Once the throttle STARTS to open…it signals for enrichment mode to start and idle mode STOPS…by breaking the throttle closed (idle) contact between # 14 and #17….and making contact between #14 on the inner wiper GROUND track…and alternately…tracks # 9 and #20 as it passes over each one.

Every time it passes over part of track #9 or # 20 alternately it fires one of the two injector pairs…without regard to current injection timing sequence. Its EXTRA injections.

3. It MUST accomplish the signal “hand off” listed above.... from idle to enrichment mode…AND….it must handle the wiper tip making contact with either the 1/3 or 2/4 enrichment track….seamlessly ….without a significant time break….or you get flat spots or misfires from lean spots.

IMPORTANT: #3 is the most important drive-ability factor….and is where that 2° of rotation thing in the book comes into play.

The idle contact and the acceleration contact should never really BOTH be closed or making contact at one time. I am not sure it would hurt anything….but there has to be a hand-off. One contact set has to open and the other has to close.

In a perfect world this “should” happen simultaneously…or with just a fraction of a degree of space/time between them.

BUT…..at the same EXACT time that the acceleration “start” contact closes….the position of the actual contact on the tip of the wiper arm MUST be either on…or very close to the lead edge of one of the alternating wiper contact strips for # 9 ….it must be within just a couple of thousandths of an inch….from moving onto one of the wiper strip contact pads and starting enrichment….like in the sketch below.

Sorry I did not redraw this…..it is just to show that the actual wiper contact DIMPLE…must be at this very close position to the first wiper pad of track #9.

Technically the wiper arm contact could even be positioned already ON or in contact with the first contact of the closest strip…which is #9….but the difficulty is that with the slop in the hub…by the time the acceleration contact is actually closed and making contact…..the wiper tip may actually in one of the spaces BETWEEN two contacts on tracks #9 and #20…leading to a FLAT SPOT.

So…really the TVS is accomplishing TWO switch hand-offs……SIMULTANEOUSLY. It is handing off the connection from the idle contact set to the enrichment contact set…with as little time/rotation gap as possible…and…connecting to and handing off the connection AND position of the wiper arm tip contact with regard to the #9 and #20 track positions.

All three of these connections must be made…so the book says….within a 2° window of throttle rotation. In reality…to prevent flat spots………at least two of these must happen within a 1° to 1.5° span of time/rotation to each other.

This is really hard to do…with wear and age….and….it can rarely be accomplished with just moving the plate an exact 2° each time. And…a sloppy throttle plate and shaft can add to this.

Adjusting this TVS:

Important Notes about getting set up for adjusting and testing:

A. you will never have a need to set your meter to any setting other than continuity. Resistance and voltage are irrelevant during the adjusting process. This is the confusing issue from the books. They state this primarily because of the VOM types of the day from 45 years ago.

B. Use some D-jet female connectors to make pigtails to attach to the pins in the TVS plug to test with….or you will never get this right because you do not have enough hands.

C. You notice that in all of the books…they say that with your volt meter connected between #14 and #9 or #14 and #20….you should hear 9-10 beeps when you open the throttle?

They say 9 or 10 beeps….and not exactly 9 or exactly 10…because in order to get exactly 10 beeps…your wiper arm tip MUST be exactly positioned right before the first line or bar on track # 9.

And….you may not be able to get that exact wiper tip position AND have the “hand-off” between idle and enrichment between the other two sets of contacts…happen on time.
So…you may actually have your wiper arm tip in the space between the first line of track #9 and the first contact line of track #20. In that case you will get 9 beeps from track #9 and 10 from track #20.

For reference…these are the wiper track pin #’s:

D. You have to do two adjustments and two observations…..and then maybe a readjustment:

NOTE: there is nothing here…..step wise…. different than the book…except that the book does not tell you anything about the IMPORTANT OBSERVATION DETAILS to make sure the adjustment is actually working.

The throttle must be closed under its normal spring pressure.

E. You are not allowed to let the throttle shaft or plate move AT ALL….not even part of 1°. Also you do NOT want to push the throttle closed excessively tight. There is a little tolerance and wear that is normal….but the shaft MUST not move at all while adjusting.

F. The screws on the TVS plate should be just snug enough that it takes careful effort to turn the TVS plate. There must be no slack between the TVS plate and the mount on the throttle body.

G. I close the throttle under normal spring pressure and use one of those small orange tipped squeeze clamps in the bell mouth of the TB just up against the plate to act as my third hand to hold the throttle plate closed.

Adjusting steps: Turn ignition off. Set VOM to continuity. Make sure the throttle plate is fully closed and clamped shut lightly.

The TVS plate screws must be just tight enough that any TVS base plate movement stays exactly where you put it without you holding it there.

1. Connect your VOM to pins # 14 and #17. Turn the TVS plate very slowly until the “whisker” contact set shown in red in the sketch below…juuuust closes and your VOM beeps. DO NOT move it any further…yet…..do not lock the screws… yet.

2. First important Observation: Look at the contact button/tip on the wiper arm. Where is in in relation to the first step or crossing point of the “zipper” on circuit track #9? It should be about 1/32”…maybe a little less… from the first contact on the wiper strip?

If this contact button on the wiper arm is too close…..like maybe just a few thousandths it is a little too close….turn the TVS plate slightly more toward closing the idle switch you just checked in step #1. It will bend that leaf switch back a little more but this is no problem.

This is why that switch is a “leaf” switch…so you can bend it back a little under pressure during positioning without damage.

The most common observed condition is that the wiper arm contact…will be some distance…like 1/32” or a little less from the first step on track #9.
This is normal.

Observed normal condition at this point: The throttle is completely closed…and the idle contact between #14 and #17 is closed and reads continuity on the VOM and the wiper arm tip contact is positioned…about 1/32” or less before the first step on track #9.

On a type 3 with the TVS mounted to the TB in the car…you may need a mirror to watch this.

Lock ONE of the TVS mounting plate screws slightly for the moment.

3. Pull the VOM probe out of pin #17 for a second. With the other VOM probe still connected to #14 and the other probe you pulled loose from #17 in your hand…. lightly touch it to the side of the acceleration enrichment switch that is connected to the wiper arm that sweeps across tracks #9 and #20…..rotate the throttle slowly toward open…. (see diagram under #6)

DO NOT connect the spare probe to either of the pins #9 or # 20 in the plug while doing this…you want to have it in your hand and placed lightly on the open side of the enrichment switch.
We are checking for enrichment switch closure right now…and not wiper arm position on track #9…yet.

Listen for the beep from your VOM as you rotate the throttle open until the enrichment switch just closes.

Now…holding the throttle plate very steady in this position. Observe where the contact tip on the wiper arm is in relation to the first contact step on track #9. It should NOT yet be in contact…but should have closed about half of that original 1/32” distance…and be about .015” from the contact strip step. Closer is better…but it should not actually be ON it ….yet.

4. Close the throttle all the way and put your squeeze clamp back on to hold it shut. Loosen the screw again…just slightly. Now…ignoring the book instructions to move the plate one whole graduation mark ….which is 2°….instead…. turn the TVS plate just very, very slightly…about half a graduation or less.
Lock the screw.

5. Connect the leads to #14 and #17 again. You are going to check to make sure that with the very fine adjustment you just made….about half the distance of one of those 2° marks on the plate….that the idle contact is still closed and still causes a beep.

6. Keeping one probe connected to #14 and the other one pulled loose from #17 again… with probe in your hand just touching the pole of the enrichment switch that connects to tracks #9 and #20 in the spot shown in the sketch below……

…..open the throttle plate until the enrichment contact closes and the VOM beeps.

Important observations at this point:

A. The enrichment switch is closed/in contact and shows continuity/beeps on the meter.

B. Check to see….If the contact tip of the wiper arm is now actually ON/in contact with the first step of wiper track #9. Ideally….it would be now…..but It usually will not be…. but will be very close….like .005” distance from making contact.

If it’s too close to tell visually…. reconnect the loose probe to pin #9…so you are connected between #14 and #9. If it beeps then the wiper arm contact is on there.
C. make sure that the idle contact between #14 and #17 now visually breaking contact …meaning open.

If this is the condition you have….enrichment contact closed and making connection..…idle contact open and making NO connection…and the VOM connected between #14 and #9 beeps showing the wiper tip is in contact with the first step of #9…..you are done!

Lock down the screws and test it to see if it has moved…which it usually has, requiring another adjustment….but we will get to that.

Further adjustment (if needed) and readjustments:

7. If #9 and #14 are not yet making contact on the VOM, it means that the wiper arm contact button is not yet on the first segment of wiper track #9. It means you need another minute adjustment of the TVS plate.

So…carefully…with the VOM connected between #14 and #9…..close the throttle plate and lock it with the clamp again.

Loosen the TVS plate screw and turn the TVS plate another very minute amount further….you are turning maybe 1/3 of one mark on the plate.

Again…ignore the book instruction to turn complete marks on the plate. Turn it just until you get a beep when connected between pins #14 and #9.

8. Lock the TVS plate….cycle the throttle and test it again.

This is a recap of what has to happen all at the same time in the TVS at this point if it’s adjusted properly:

A. the Idle contacts must be closed/making contact when the throttle is completely closed.

B. The enrichment contact must be able to be closed/make contact within about 1° of throttle opening rotation….and the idle contact must be able to open/break contact within that same 1° of rotation.

C. the wiper arm must make contact with the first step of wiper strip #9 within no more than 1° further throttle opening rotation or there will be a flat spot or misfire because there will be a long gap of time before you get any fuel.

With wear, and abuse….it’s hard to get all three of these things to happen within 1° of each other.

Trouble shooting:

Usually if this is not all happening…. it’s usually not primarily a wear issue between the “D” shaped hub on the throttle shaft….it’s mostly slightly bent or worn contact leaves in this particular type of TVS.

The alternate and most common problem…is that the wiper arm contact location for track # 9 may be fine…but the “hand-off” gap between idle and enrichment may be too wide….so you get a big flat spot….because both idle and enrichment switches are open/not in contact. I call that “switch float”.

You are not getting idle or enrichment for a period of maybe 1°-2°. Schematic wise…it looks like this:

This happens usually when the contacts are worn or bent. It takes too many degrees of throttle rotation to make the hand off. It means that either you have a big time lag…or by the time the enrichment contact closes the wiper tip is in the wrong place and you get a hiccup.

To fix this…you can bend the contact arm..NOT THE WIPER ARMS…..BUT...AND….do not bend the small copper arms on the enrichment switch FIRST.

You bend the ones on the idle side FIRST if you need to make an adjustment.
To do this….adjust the TVS the best you can first. Then open the throttle and lock it open just at the point where the enrichment switch is closed and the contact wiper tip is exactly on the very leading edge of the first mark of track #9….then bend the idle contact leaf nearest the hub….so it is maybe .005" closer…then bend the other contact of that set to match so the operating gap is the same as it was. Then check for function readjust the TVS again.

If anything is not clear or gets confused…please let me know.
Ray

Tue Jun 12, 2018 1:53 pm

Thanks Ray! In step 3 you mention to put the probe tip on the acceleration switch pole that makes contact to #9 and #20. Then in step 6 you say to touch the probe to the other pole of the acceleration switch. Your picture seems to show the green negative probe touching the pole of #9 and #20 as in step 3. Am I wrong or is the green probe supposed to be on the other acceleration pole?

In step 4 which direction do I turn the plate very slightly.

Tue Jun 12, 2018 4:54 pm

tmitoraj wrote: Thanks Ray! In step 3 you mention to put the probe tip on the acceleration switch pole that makes contact to #9 and #20. Then in step 6 you say to touch the probe to the other pole of the acceleration switch. Your picture seems to show the green negative probe touching the pole of #9 and #20 as in step 3. Am I wrong or is the green probe supposed to be on the other acceleration pole?

In step 4 which direction do I turn the plate very slightly.

Thanks for the feedback. To clarify:

1. what you are doing at step #3...is identical to what you are doing at step #6.

To clarify....I added to step #3 to look at the diagram below step #6. I also added to the image....a red line from teh contact you need to have your probe on so its clear what tracking you are checking.

To further clarify....at a quick glance....without inspecting what you are putting your probe on...you WILL get it backwards. The copper contacts...cross over each other.

This is the altered sketch I added to clarify which half of the switch to put your probe on. You can now see that just because the wiper arm is on the outside...does not mean that its switch contact is on the outside. :wink:

Here is a shot of that from your picture:

Step number 4....which way to turn: Ok...this is not just for you...but I want you and everyone to think through this answer.... to get your heads inside of the TVS.

What you are seeing or how you are looking:

Looking right at the TVS plate from the side...just like in my diagrams.....

A. You are holding the throttle plate and therefore the throttle shaft stationary...locked...right?

B. and with the throttle plate closed and locked....the hub in the center of the TVS on the throttle shaft...is pushed hard up against the idle contact switch holding it together/closed...right?

So...if the throttle is closed....and you turn the TVS plate COUNTERCLOCKWISE....it crams the hub harder up against the idle contact set...which it is already up against and holding closed/on.

This idle idle position switch position was already checked/set in step #1....and that was the only time we turn the TVS plate counterclockwise

So in step #3 and Ste[ #4 and all subsequent steps...we will always be turning the TVS Plate...CLOCKWISE...away from the idle contact set.

This is WHY you want to only move in very small increments...not just whole 2* blocks.

That idle contact set has some give built into it because its a leaf spring contact set.
Remember?...that in step #1...we noted that to get both the wiper arms and the enrichment contact set into the correct.....pre-position..... WHEN the throttle is closed which means the idle contact set is also closed......
......we over rotated a little bit (if necessary) COUNTERCLOCKWISE.....to spring load that idle contact closed a little bit.

Once that idle contact set was adjusted in step #1....all movements/adjustments of the TVS plate will always be in teh clockwise direction...and after each adjustment.....you are closing the throttle plate all the way...and rechecking that when the throttle plate is closed...the idle contact set is also still closed.

This is why there are so many steps......you adjust TVS plate....close throttle ...check with VOM...observe....adjust TVS plate....close throtle.....check with VOM...observe.
:wink:

Ray

Tue Jun 12, 2018 8:30 pm

Am I in the Bay forums? :D

I miss the good old days of "remove air cleaner- loosen TS screws- rotate TS all the way CCW, making sure throttle is closed- turn key to "run" position- adjust switch clockwise till it clicks, then 2 more hash marks- lock it down- done."

If it didn't work it was defective and you replaced it.

I hate thinking. :lol:

Tue Jun 12, 2018 8:54 pm

Tram wrote: Am I in the Bay forums? :D

I miss the good old days of "remove air cleaner- loosen TS screws- rotate TS all the way CCW, making sure throttle is closed- turn key to "run" position- adjust switch clockwise till it clicks, then 2 more hash marks- lock it down- done."

If it didn't work it was defective and you replaced it.

I hate thinking. :lol:

:lol: ...really...with the two wire....and even the three wire it was that simple....and not far off with the late 4 and 5 wire!

As I noted in the beginning of this......if the TB and throttle shaft are tight.....and the TVS is either new or in very good shape.....95% of the time.....its that simple.

However....most have "some" slop in them now.....and new ones do not grow on trees any more. The "book" directions still stand but to get it spot on you need to do a little checking. Ray

Sat Jun 23, 2018 2:59 pm

Back at it. You can see in my pictures that the middle "button" that connects to the throttle shaft has play. I can rotate about .04 inches without the throttle shaft turning. I think that this play is making adjusting per Rays directions difficult. Should there be movement of the button about the shaft without turning the shaft? If so how do I adjust the play out? Thanks

The throttle is closed in this picture. Picture meant to show free play not contact placement. Just to verify from top to bottom the wires on the TVS pin assembly are 17,14,9, and 20. Thanks

Sun Jun 24, 2018 12:08 pm

tmitoraj wrote: Back at it. You can see in my pictures that the middle "button" that connects to the throttle shaft has play. I can rotate about .04 inches without the throttle shaft turning. I think that this play is making adjusting per Rays directions difficult. Should there be movement of the button about the shaft without turning the shaft? If so how do I adjust the play out? Thanks

The throttle is closed in this picture. Picture meant to show free play not contact placement. Just to verify from top to bottom the wires on the TVS pin assembly are 17,14,9, and 20. Thanks

No....That play between shaft and D shaped hub.... is NORMAL and required.....

This is what makes TVS adjustment.....not just a "move it one notch" and lock it down process.

Understand.....when the throttle is closed .....and the TVS is properly adjusted.....the hub....is very lightly spring loaded.....forward.....towards enrichment.......by the enrichment off/idle contact switch leaves....which are a spring. And at the same time the throttle plate and shaft are kept pulled closed by the throttle return spring......loading the shaft in the opposite direction toward closed/off.

The whole object of this.....is that when you push the throttle..... the throttle plate will move just about 2° toward open before taking up the slack in the D shaped hub and starting to move the hub and wipers toward enrichment.

The throttle NEEDS to open this 2° .....BEFORE enrichment starts to get air moving into the engine to mix with the fuel you are about to give it.....AND....give a small but critical drop in vacuum to trigger the MPS to give SOME enrichment.

This is what this adjustment is ALL about. You need that 2° of throttle movement BEFORE enrichment starts......or you get a rich stumble......BUT..... you also cannot have MORE than 2° movement before enrichment starts.....or you get a lean stumble.

And.....most importantly.....because of how critical this extra fuel enrichment is to off the line drivability....and especially shift points and the "bucking syndrome".........DO NOT......start adjusting the TVS......until FIRST adjusting the valves and ignition correctly, making sure advance is working and coming in on time.......and only then adjust the TVS.........and then....when its nominally driveable (knowing the TVS may still cause issues off the line).....make sure your fuel mixture at the MPS and with fuel pressure is spot on.

This is critical to getting very smooth driving and perfect fuel mixture.

Why? Because if you are already running rich or lean.....the TVS is an intermittent load enrichment device. Its input is a multiplier to whatever fuel mixture the MPS, fuel pressure and TS-1 and 2 are already giving you. If your baseline is wrong.....the TVS can make it,feel worse.

Really......if you are correctly adjusting the TVS.....you can adjust it at any time. You do not have to adjust the ignition first......but I suggest you do all of the footwork first.

The volt meter and observation of the contacts will tell you when the TVS is adjusted properly.....but not being used to it.....when a perfectly adjusted TVS causes the engine to run "different"......too many people starting dicking with it.....when the problem is really elsewhere. Ray

Sun Jun 24, 2018 12:31 pm

I explained a piece of that last answer poorly. So to clarify......a small amount ....the smalleat amount.....of the slack you are seeing between shaft and hub.....is actually between the shaft and the walls of the D shaped hole in the hub. That hog ring/ C-clip keeps this uniform.

Most of the slack is between the shaft hub and the wiper arm hub.....but the amount of slack you are seeing ia pretty normal. It is only deemed excessive......if you notice that the slack eqyals more than 2-3° total rotation at the wiper tips. Ray

Sun Jan 22, 2023 3:23 pm

I have my air intake assembly with TVS attached on my bench. I attached a throttle return spring to the throttle assembly to keep tension on it while closed. I adjust the idle contacts and notice a proper position of the pin before the first contact on acceleration strip. When I perform the next step I rotate the throttle waiting for the acceleration contacts to close. This is what happens. Opening the throttle moves the TVS hub and. Closes the contacts before there is any movement of the wiper arm. This is because of the small amount of slack in the hub. It turns and closes the contacts before the wipers move. What is the best way to adjust out the slack so I don’t get a big lag? As I am moving the throttle assembly towards open there is just a small amount of play before it catches the throttle plate and starts it moving open Thus moving the pin. Thanks Tom

Thu Jan 26, 2023 11:29 am

tmitoraj wrote: I have my air intake assembly with TVS attached on my bench. I attached a throttle return spring to the throttle assembly to keep tension on it while closed. I adjust the idle contacts and notice a proper position of the pin before the first contact on acceleration strip. When I perform the next step I rotate the throttle waiting for the acceleration contacts to close. This is what happens. Opening the throttle moves the TVS hub and. Closes the contacts before there is any movement of the wiper arm. This is because of the small amount of slack in the hub. It turns and closes the contacts before the wipers move. What is the best way to adjust out the slack so I don’t get a big lag? As I am moving the throttle assembly towards open there is just a small amount of play before it catches the throttle plate and starts it moving open Thus moving the pin. Thanks Tom

Sorry for the delay in reply. I was out of town on business.

OK....so let me try to lay out what you are describing as I work through what you wrote.

1. So you have the throttle plate (and therefore the D-shaft) properly spring loaded so its just like it is when installed in the car and running.

2. At this point, the pair of points attached to the plate by the single screw are closed....or should be.

3. The wiper arm outer contact...the one that slides over the alternating contacts for each channel....should be NOT touching the first contact on the "zipper" strip...but should be poised maybe 0.005" away from making contact.

But what is happening....is that when you turn the throttle shaft.....the D- shaft moves the hub enough that the idle contact which signals throttle fully closed.....opens the idle contact FIRST.....and then closes the enrichment contact on the wiper arm....BEFORE the wiper arm has moved onto the first contact of teh "zipper" strip.

In a perfect world....the enrichment contact set for the wiper arm would close nearly simultaneously at the point the wiper arm moves onto the contact.

But, that is hard to time. What you do NOT want is that contact to close too late....meaning the wiper arm is moving BEFORE the contacts close. This can happen and when it does, the wiper arm is lagging and has moved off the contact and into the gap between the two wiper arm channel strips by the time the contact set has closed.....all the while the throttle is moving toward open...and you get a very short lean spot or stumble.

So to be safe...you WANT the wiper arm contact to close BEFORE the wiper arm starts moving. So what it is doing is correct.

But what you do NOT want, is for the idle contact to open and the enrichment contact to close and then have a long time lag between when the wiper arm moves.

So.....before trying to do anything to take up slack in the D-shaft and hub.....

1. Start like you are...spring attached, throttle closed....and adjust the plate until by rotating it until the wiper arm contact is exactly where it is supposed to be...poised just a few thousandths from making contact with the first step on the wiper strip. Tighten the screw lightly.

2. cycle the throttle plate and bring it back to closed under spring pressure. Check the wiper arm tip position again. If it has moved onto the first enrichment contact or has moved away from the contact....make a very slight plate adjustment in whichever direction is needed until you get it right.
Lock the plate down.

So far you are just adjusting the plate to achieve wiper arm position in the the "fingertip" position.

3. With the throttle plate still held closed in the idle position by spring pressure.....the idle contact should be closed.

4. Unlock the screw that holds the idle contact to the plate. Push/move it slightly to push against the plastic cam that is holding it closed. Push it until you see it moving the plastic hub and the gap on the wiper arm contact is NARROWING.

What you are doing: You are using the spring force of the idle contact to pre-load the plastic hub on the D-shaft toward the wiper arm contact.

You want to close up the gap in the wiper arm contact by a little less than half but do not let the contacts touch.

As you start to slowly open the throttle....observe both sets of contacts. You want to make sure that the idle contact set....comes apart...shortly....very shortly.... before the wiper arm contact set closes.

NOTE: if the wiper arm contact set closes....and the idle contact set is still closed (in contact) as well...then you have pre-loaded the idle contact slightly too much. Take some tension off of it until you get it right.

You want the shortest amount of time you can get for the "hand off" of idle contact open to enrichment contact closed.

Once you get that relationship correct....then close the throttle under spring pressure...and re-check the wiper arm tip position. If its off....readjust the plate rotation position.

Then re-check the idle and and enrichment contacts and adjust again.

You need to work back and forth between these two adjustments.

I have a "possible" solution...if you REALLY end up needing to make up slack in the D-hub.....but try these adjustments first. Ray

Sun Jan 29, 2023 1:03 pm

Ray! That was the piece of the puzzle I needed. Adjusting the idle circuit block with that screw did the trick. This should be a Sticky!

Fri Feb 10, 2023 7:07 am

Ray, when accelerating the wiper switch makes contact alternatively with contacts on the zipper plate . What happens when you are driving. If going down the road with no change in throttle movement, what if the wiper arm happened to stop on a gold strip. Would those injectors continue to fire additionally?
If you are driving with some small changes in throttle movement because of foot movement on the accelerator pedal, does the TVS activate the injectors with just casual driving not active accelerating? Thanks Tom

Mon Jul 17, 2023 10:44 am

Tmitoraj had some tuning questions. Its been busy...sorry or I would have gotten back to this a few weeks back.

Question #1 from back on June 23rd:

Quote: Back at it. You can see in my pictures that the middle "button" that connects to the throttle shaft has play. I can rotate about .04 inches without the throttle shaft turning. I think that this play is making adjusting per Rays directions difficult. Should there be movement of the button about the shaft without turning the shaft? If so how do I adjust the play out? Thanks

The throttle is closed in this picture. Picture meant to show free play not contact placement. Just to verify from top to bottom the wires on the TVS pin assembly are 17,14,9, and 20. Thanks

Question #2 from July 16:

Quote:
Ray, I have been following your instructions on adjusting the 4 prong TVS and I can’t overcome the slack in the center hub. I keep getting a beep on 17, and 9,20 whisker before there is any movement of the arm on to the first contact strip. It seems that if I bent the whiskers apart some it might allow the contacts to close when the arm is on the first contact strip. That might overcome the slip in the hub which seems to allow the contacts to close before movement of the contact arm. Does this sound reasonable? Any other ideas? You can follow our conversation on the type 3 early TVS thread. Thanks a lot. Tom

So, the picture you posted June 23rd is instructive in several ways:

As a recap so you do not have to keep scrolling backwards, below is your picture with the wire/pin #'s applied and a few cryptic marks I will explain:

First: a couple of things you must remember and keep in mind:

1. There are two sets of contacts in these and all TVS. One for off/park/throttle closed and one for on/inject/enrich. In the picture below the “park/off” contact set is in the red circle with 14 and 17. The “enrich/on” contact set is in the redcircle with 20 and 9.

2. At park/off the 17/14 contact set is closed/touching together and the 9/20 enrich/on contact set is open/not touching.
During enrich/on cycle when you open the throttle, that reverses and the 14/17 contact set opens and the 9/20 contact set closes.

3. These two contact sets (depending on the hub tolerance and wear) “MAY” both be “open” for a very small amount of degrees of rotation…..BUT….they can never both be CLOSED at the sme time.

4. MOST IMPORTANT RULE TO REMEMBER:
Ideally, the 14, 17/park contact set MUST be open…not touching… AND…. the 9, 20/enrich contact set MUST be closed….touching….BEFORE the wiper arm starts to move.

Why is this?

Because if 14/17 contact set does not break contact, then the 9, 20 contact will not be “live” and you get no enrichment.

The IDEAL situation is to have the 14, 17 contact break open the smallest amount of time/degrees as possible before the 9, 20 contact closes, to not have a time lag.

SIMULTANEOUSLY…..that same small gap/time lag should also apply to how long it takes the wiper arm to move onto one of the hash markes on the wiper strip.

However, Its too difficult to get all three of these “time gaps” to happen at one time….so to take the wiper arm tip out of the equation….it should be “parked” within a couple of thousandths from the edge of the first hash mark or right on the start of the first hash mark so that the very millisecond that the 9, 20 contact closes….you have instant enrichment start with no time lag.

An observation based on your picture from June 23rd:

Observation:

You say the throttle is “closed” in this picture. You also note that you are only trying to illustrate the amount of slack in the hub at the D-shaped shaft. I get that.

I am assuming that you are holding the throttle plate closed and have rotated the plate counter-clockwise for this picture right?

Note the yellow arrow points to how far you are advanced onto the wiper strips. You are either on strip 3 or in between strip 3 and 4. The blue line shows how far you are from the maximum “park”….throttle closed….position.
This is too far.

Its not the slop in the hub you are fighting. It’s the adjustment/position of the 14, 17 contact set.

Do this:

1. Clamp the throttle plate closed

2. Turn the TVS plate clockwise until the wiper arm tip on track # 14 is approximately on the blue line park area.

Really, since the inner wiper arm in contact with track #14 moves at the same time as the outer wiper arm that contacts tracks #’s 9 and 20, you really want to make sure that the little “pellet” or ball on the outside wiper arm is either JUST touching the first mark of track #9 or is just a couple of thousandths from touching it. A really minuscule gap. Track #9 is the first wiper strip in line.

3. At this point you TEST THIS by the book method of rotating the plate CLOCKWISE by 1 mark….which is ~2°. As you rotate through that 2° mark….the 14, 17 contact should open. And when you rotate even a half or third of a degree further, the 9, 20 contact should close and the outer wiper arm tip should be in the middle of the first tick mark on wiper track #9.

What will usually be found wrong at this point:

4. You will probably notice that with the throttle plate clamped closed, and the TVS plate rotated counter clockwise to put the wiper arms in the park position…..that the 14,17 contact set is BENT backward too far.

THIS IS THE PROBLEM YOU ARE HAVING!

What you need to do is:

5. As per above, clamp the throttle plate closed. Use a clamp or something. You will need both hands. Rotate the TVS plate counter clockwise until the wiper arms are in the position I described above in #2. At the blue line and the first hash mark of circuit #9. Contact set 14, 17 should be closed-touching each other and contact set 9, 20 should be open- not touching each other.

LOCK THE PLATE SCREW LIGHTLY…temporarily…to hold this adjustment.
6. Loosen the screw in the yellow square in the picture below: Rotate the contact set clockwise just slightly until the 14, 17 contact set just opens up. Now close it by rotating the contact assembly counter clockwise until it just touches and closes the 14, 17 contact set.

All this while, the wiper arms should be stationary and the 9, 20 contact set should remain open.

7. Now, lets do the factory adjustment. Make sure the throttle plate stays clamped closed. Rotate the TVS plate clockwise 1 graduation mark which is ~2°.
During this 2° rotation, the 14, 17 contact should NOT open up…..but should be very close to it.

Also, the 9, 20 contact set should NOT close…but should be very close to it.

Also, the wiper arm tip should not be fully on the first hash mark of wiper strip #9 but should be either just a few thousandths from touching or just touching at the very leading edge of it.

The OBJECT being is that another 1/2 degree of rotation should close contact 9, 20 AND simultaneously have the wiper tip somewhere on the first hash mark of contact strip #9.

So, the tolerance in your “D” shaft may or may not be excessive….but you should be able to work around it. The trick is to do that by adjusting the position of the 14, 17 contact set via the mounting screw on the TVS plate.
The reason that 14/17 contact set is installed with a screw is because all of this had to be done at the factory on some jig.

Over the eons, you get throttle plate/shaft wear and maybe some bushing on shaft wear and some fatigue to the contact set spring rates etc. Or, it could just be that a previous owner played with that screw!
Then this “sensitivity” adjustment needs to be reset.
Is this all clear?

Ray