TPS variations - has anyone else noticed this ?, trouble shooting and comparing 2 with same part numbers but different stop tabs etc Options

[DRPHIL914]

i will post a picture here of 2 OE TPS with part number that cross references to the 75-76 2.0 D-jet cars.

i recently pulled mine due to it bucking badly @ 2800-3400 rpm on part load or mild acceleration.
i also have one from Gatornapper to test for him and he is sorting out his D-jet parts and prepping to eventually going back from carbs to FI.
What i found was that the stop peg is located on a different place. his
essentially stops the tps from going all the way to the bottom at idle but not at the top on acceleration.
mine on the right. stops the pivot of the shaft from going all the way on the top and keeps it from being able to go off track on max, his would not.
they have the same part number. neither had been tampered with.
also i bought mine as an NOS part 7-8 years ago and now may need to be replaced.
his on the left has much more wear, actually live testing it causes same bucking but at a different lower rpm, due to wear pattern.


any thoughts? i will be putting a new board on mine as soon as it arrives
Right now i am running with it unplugged and no skip buck or hesitation now. i had been thinking it may have been an issue with my rebuilt MPS or developers valve set up or a wire shorting somewhere else, but it’s the TPS.

[SirAndy]

The part number printed on the boards is different. Yours seems to end with 006/008 (?) while the other one seems to end with 013

(IMG:style_emoticons/default/idea.gif)

[DRPHIL914]

The part number printed on the boards is different. Yours seems to end with 006/008 (?) while the other one seems to end with 013

(IMG:style_emoticons/default/idea.gif)

back side the VW numbers both end in 111 but left one has an “A” thats the only difference. top number is hard to see but same on the back, but yes I see the board number appears to be different on the front. I don't see a dffference in the circuit though.

[DRPHIL914]

The part number printed on the boards is different. Yours seems to end with 006/008 (?) while the other one seems to end with 013

(IMG:style_emoticons/default/idea.gif)

i looked closer and it is 006 on that one. , so good eye the boards have a different number but the case and back are the same except for the A at end of the VW number on his.

[Nojoah]

Hmm interesting. The TPS I pulled off of my stock 74 2.0 -

[DRPHIL914]

Hmm interesting. The TPS I pulled off of my stock 74 2.0 -

Interesting, that is really worn bad!! same part # on the board/13 , as the one in my pic on the left , what is the part number on the back side?

[Nojoah]

Interesting, that is really worn bad!! same part # on the board/13 , as the one in my pic on the left , what is the part number on the back side?

Definitely worn - pulled it off for replacement as I was experiencing similar bucking. Sorry I don't believe I have a picture of the part number on the back this was a few weeks ago. (IMG:style_emoticons/default/confused24.gif)

[bdstone914]

Try a pencil eraser to clean it up. If the metal is gone replace it. Shorten the pencil and put it in a cordless drill an medium speed.

[nordfisch]

You won't have to replace the board.

Just clean it using a fibre glass pencil. Bend the feelers just a little bit sideways so they run on fresh material. < your outer feeler seems to be misadjusted >

Don't oil or grease anything. There is so low electrical current that even WD-40 could make problems. Just clean the board and all will be fine.

---------------------------

I'm quite sure your unit is the only one that was assembled properly in the factory.
The other units will not give correct idle signal because the arm will never reach the stop-sheet. The arm turns by exactly 90° - no more. You can see the marks of the full-throttle-opening on the board - turn the arm back by 90° and the arms of both othe units will not reach the stop sheet!

Idle signal is given only when the arm reaches the stop-sheet, otherwise the signal is broken by the slide-contact located in the arm.

This misfunction (missing idle signal) will not affect any other function of the TPS.

It will only disable the function of adjusting idle CO at the ECU potentiometer and make idle adjustment more difficult.

-----------

It would be interesting to know the production code of the 3 units. The left one has the code '426' = June 1974. Nojoah's code is '329' = September 1973.

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The production marks / numbers printed on the boards don't matter at all. They have identical design, that is what matters. Don't care about this.

Regards
Norbert

[DRPHIL914]

You won't have to replace the board.

Just clean it using a fibre glass pencil. Bend the feelers just a little bit sideways so they run on fresh material. < your outer feeler seems to be misadjusted >

Don't oil or grease anything. There is so low electrical current that even WD-40 could make problems. Just clean the board and all will be fine.

---------------------------

I'm quite sure your unit is the only one that was assembled properly in the factory.
The other units will not give correct idle signal because the arm will never reach the stop-sheet. The arm turns by exactly 90° - no more. You can see the marks of the full-throttle-opening on the board - turn the arm back by 90° and the arms of both othe units will not reach the stop sheet!

Idle signal is given only when the arm reaches the stop-sheet, otherwise the signal is broken by the slide-contact located in the arm.

This misfunction (missing idle signal) will not affect any other function of the TPS.

It will only disable the function of adjusting idle CO at the ECU potentiometer and make idle adjustment more difficult.

-----------

It would be interesting to know the production code of the 3 units. The left one has the code '426' = June 1974. Nojoah's code is '329' = September 1973.

-------------------------

The production marks / numbers printed on the boards don't matter at all. They have identical design, that is what matters. Don't care about this.

Regards
Norbert

231 is the number on mine, you are saying that the production date would be "72 31 week)?

[nordfisch]

231 is the number on mine, you are saying that the production date would be "72 31 week)?

231 means November 1972

Regards
Norbert

[DRPHIL914]

231 is the number on mine, you are saying that the production date would be "72 31 week)?

231 means November 1972

Regards
Norbert

interesting since the part number coinsides for 2.0L cars yet no 2.0's were made in 72 correct? hmmmmmm

[nordfisch]

231 is the number on mine, you are saying that the production date would be "72 31 week)?

231 means November 1972

Regards
Norbert

interesting since the part number coinsides for 2.0L cars yet no 2.0's were made in 72 correct? hmmmmmm

The Bosch listing says it was first produced in 1972/8, developed for VW-Porsche 2.0

VW-Porsche model year 1973 starts 1972/7. I don't know when the production of the 2.0 started...

Regards
Norbert

[DRPHIL914]

ok update:

took advice here and i cleaned the surface and leads , pencil eraser then bent the outside longest one so that it could track along a clean unworn path and Presto!! perfect run on 45 minute drive with no hesitation or bucking!! i will hold on to the new Sprinkle board just in case or for future replacement but right now no need to change it!
i have to say in 12 years of ownership i have never had the car run better, it’s always had a bucking slight or lots, with other TPS’s used, until now.
now to fine tune my idle and accel/decel- decel is very slow to come down after letting up on pedal- it’s not the throttle body or the springs. that comes back fast and tight tho are all new including pedal and accel cable, so why would this be?

You won't have to replace the board.

Just clean it using a fibre glass pencil. Bend the feelers just a little bit sideways so they run on fresh material. < your outer feeler seems to be misadjusted >

Don't oil or grease anything. There is so low electrical current that even WD-40 could make problems. Just clean the board and all will be fine.

---------------------------

I'm quite sure your unit is the only one that was assembled properly in the factory.
The other units will not give correct idle signal because the arm will never reach the stop-sheet. The arm turns by exactly 90° - no more. You can see the marks of the full-throttle-opening on the board - turn the arm back by 90° and the arms of both othe units will not reach the stop sheet!

Idle signal is given only when the arm reaches the stop-sheet, otherwise the signal is broken by the slide-contact located in the arm.

This misfunction (missing idle signal) will not affect any other function of the TPS.

It will only disable the function of adjusting idle CO at the ECU potentiometer and make idle adjustment more difficult.

-----------

It would be interesting to know the production code of the 3 units. The left one has the code '426' = June 1974. Nojoah's code is '329' = September 1973.

-------------------------

The production marks / numbers printed on the boards don't matter at all. They have identical design, that is what matters. Don't care about this.

Regards
Norbert

[DRPHIL914]

thought i’d post a picture after cleaning up the boards.
This is gatornapper’s , cleaned up like new.
you can hold onto it until
you are ready to put the FI on the car but so far your ECU, and TPS should be good, the MPS has to be rebuilt but that’s not hard. the one i had i was going to offer up the diaphragm for you has a tear in it. at some point get a kit from Tangerine, we can rebuild and tune it up. i know you got your carbs dialed in now so it’s hard to argue with making a change . i can say my FI has never stranded me. now with the TPS figures out and a nice tuned MPS it’s almost set.
one issue i have is when i just start the car idle is too low for about 1-2 minutes then comes up once it warms up some, and that’s at 75-80 degrees outside temp- once it comes
up it’s what you would expect with aar open ,
then once it closes it comes down to perfect idle about 950rpm. wondering if this is a CHT that has too low of resistance when cold, but balanced out once he’d temp comes up a bit?

[nordfisch]

Hi,
the cold engine needs extra fuel AND extra air.
Seems the AAV doesn't open enough in cold state.

Regards
Norbert

[DRPHIL914]

Hi,
the cold engine needs extra fuel AND extra air.
Seems the AAV doesn't open enough in cold state.

Regards
Norbert

I appreciate the suggestion, I checked this last night, appears full open and closes up as well, other thought was the CHT resistance at cold, this seems to be off, I added an adjustable rheostat goes from 5-500ohms, to the cht line just to see if that helps, and it does bring cold start up idle up some, then once warmed up fully , idle air valve closes and the idle comes back down to a proper 900, might try a different new 012 cht from 914rubber tonight too, but the extra resistance did the trick.

the other issue was that on acceleration it was very slow to return back to idle even with me manually operating the accel cable at the throttle body, and quickly closing it, so I looked closer at the decal valve, which I recall I ddint have this issue until installing that. disconnecting the decal allows the rpms to return back quickly to normal not hang up and "lag" . not sure what the d-jet experts make of this but with out the decal hooked up all seems better.

will keep playing around with this, but I cn tell you I had it hooked up according to the pictures I had for this.

[Gatornapper]

Phil -

"disconnecting the decel allows the rpms to return back quickly to normal not hang up and "lag" . not sure what the d-jet experts make of this but with out the decal hooked up all seems better."

It's been a number of years since I've worked on FI systems in any depth, but I believe the decel lag created by the device is purely for emissions purposes - a slow decelleration produces less emissions that a quick cut-off of fuel.

If this is correct - you don't need the decel valve - and, as you said, the car will run better.

Some of the FI gurus here can tell you if this is correct or not.

GN

Hi,
the cold engine needs extra fuel AND extra air.
Seems the AAV doesn't open enough in cold state.

Regards
Norbert

I appreciate the suggestion, I checked this last night, appears full open and closes up as well, other thought was the CHT resistance at cold, this seems to be off, I added an adjustable rheostat goes from 5-500ohms, to the cht line just to see if that helps, and it does bring cold start up idle up some, then once warmed up fully , idle air valve closes and the idle comes back down to a proper 900, might try a different new 012 cht from 914rubber tonight too, but the extra resistance did the trick.

the other issue was that on acceleration it was very slow to return back to idle even with me manually operating the accel cable at the throttle body, and quickly closing it, so I looked closer at the decal valve, which I recall I ddint have this issue until installing that. disconnecting the decal allows the rpms to return back quickly to normal not hang up and "lag" . not sure what the d-jet experts make of this but with out the decal hooked up all seems better.

will keep playing around with this, but I cn tell you I had it hooked up according to the pictures I had for this.

[JeffBowlsby]

Using the decel valve is said to reduces stress on the MPS diaphragm.

[DRPHIL914]

Using the decel valve is said to reduces stress on the MPS diaphragm.

yes I have heard that so was reluctant to do this but looking at the set up I don't see how directly it would do that , its not like the MPS vac is hooked up to the decal directly , so other than just only allowing a slightly slower decel to minimize a sudden pull down or back pressure , I don't see how it would really protect it. that last MPS disc that gave out back a few months ago with the decel hooked up properly.

BTW Jeff, I am ready for you to rebuild that MPS I sent you !!!

@jeffbowlsby