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.

[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.