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Posted by: jsayre914 Jul 27 2012, 11:47 AM

I have a 2.0 D-jet setup. The classic bucking at constant speed. I have disconnected the TPS and the car runs super smooth with no bucking at all. The board has been replaced with Dave's board. I have adjusted it as per the pelican article. I have searched and searched. I printed the picture out of what it should look like before you put the cover back on. My adjustment is perfect. My TPS is adjusted right where it should be BUT is still Bucking




Can there be somthing eles wrong with a TPS other than the correct adjustment??


Should I get another TPS to try it?

Posted by: ape914 Jul 27 2012, 11:52 AM

new board in the tps? I'd try the old board and see if it goes away. Did it have this problem before the new board was installed?

Posted by: jsayre914 Jul 27 2012, 12:56 PM

no idea, this motor was just built. the original tps was sitting in a box for 4 years or so, i never tried it, but it sure looked worn to me

Posted by: yeahmag Jul 27 2012, 01:04 PM

Have you checked your fuel pressure?

Posted by: The Cabinetmaker Jul 27 2012, 01:05 PM

Did you use an Ohm meter to set it? did you check it at the ecu harness connection? I have installed a new tps board that i got as a door prize at last years MUSR. I don't know who made or where it came from, but it was not good. Retry you old tps. If its shot, i''l send you a known good one to try out.

Posted by: 914_teener Jul 27 2012, 01:08 PM

+1

Posted by: SLITS Jul 27 2012, 01:18 PM

Did you check that all the finger are actually touching the board with enough tension or the contacts on the fingers are not broken off?

Posted by: jsayre914 Jul 27 2012, 03:39 PM

I did use a multimeter on the ohm setting to set it. Fuel pressure is strong at 29psi and again with the tps unplugged, there is no issues at all (other than no acceleration)





TPS

T= Total
P= Piece
of
S=_____

Posted by: SLITS Jul 27 2012, 03:52 PM

Let me see if I have any TPOSs left & I'll send you one (I think I gave them all away).

Posted by: The Cabinetmaker Jul 27 2012, 03:57 PM

I got him one going Ron. I have a few.

Posted by: jsayre914 Jul 27 2012, 04:35 PM

You guys are the best

Posted by: davesprinkle Jul 27 2012, 09:20 PM

Hey guys,

Seems like a couple of you are having some trouble with the replacement TPS board. Send me a PM and we'll discuss options for checking out the sensor.

-dave sprinkle

Posted by: jsayre914 Jul 29 2012, 02:26 PM

So, why is the shop manual procedure for adjusting different than the pelican procedure ?

Pelican: using a meter on the correct leads, start turning the tps clockwise until you see 0, STOP. now continue clockwise one more hash mark exactly and then tighten down. Your finished.

(with this one, once you are at 0 then you move it one more mark, you are no longer at 0 when you tighten it down)

Shop: using a meter on the correct leads, start turning the tps clockwise until you see 0, STOP. Tighten down. Your finished.





p.s. I tried both ways and it didnt seem any different. I have a TPS on the way from Cabinetmaker and I just sent Dave a pm

Posted by: jsayre914 Jul 30 2012, 10:10 AM

Posted by: jsayre914 Jul 30 2012, 10:10 AM

Double post
oooops

Posted by: r_towle Jul 30 2012, 12:46 PM

This is what it needs to look like at rest with the throttle plate closed.
If you look a the board it has different contact areas and those represent different levels of fuel based upon the position of the switch. (hope that makes sense)

Consider that our Djet system is not super flexible and its really a hard coded map of a certain amount of duration to open the injector with almost zero tuneability.

There is a special Idle circuit that you need to make sure is enabled when you have the throttle plate closed and that is the Ohm meter test that verifies that you are resting on the correct idle circuit...if you line up the switch properly, the ohm meter lets you know, then lock it down and forget it.

I have no idea what Pelicans extra step is for, but remember it was not written by Bosch, so I favor the Bosch instructions and it has never steered me wrong.

The reason the switch is adjustable at all is because they made one TPS switch for about 15 cars and each throttle body is a bit different.

This is a set it and forget it switch...its really not adjustable or you doink the whole system.

The best and most perfect way to set the switch is by eye.
Remove the throttle body, pull off the black cover and set the switch while looking at it.
You can verify its properly done with an ohm meter, but visual always works.

Damn, wrong computer....I will find the pic in a second.

Rich

Posted by: r_towle Jul 30 2012, 12:48 PM

Look here

http://www.914world.com/bbs2/index.php?showtopic=108094&hl=throttle++position

Posted by: Spoke Jul 30 2012, 07:24 PM

What is it in the TPS that causes bucking at constant speed?

I know it has a throttle closed switch to engage the idle circuit in the ECU. But in this case the throttle is open a bit and so the throttle closed switch should be open and out of the circuit.

Then there are the fingers and associated contact to sense if the throttle is moving in the open direction. I guess if this contact is not clean the resistance from the TPS could be changing with constant open throttle causing the ECU to add spurts of fuel through the injectors.

Is this contact clean and in good operating condition? Did you measure the resistance when opening the throttle? you should get zero-open-zero-open on one pole and open-zero-open-zero on the other pole.

Posted by: jsayre914 Aug 1 2012, 03:43 PM

Got it today, just went out to put it on on my lunch break.
I am working till 8pmEST so I will not know if it runs any better till after then. I just adjusted it to exactly where it 0s out like you said.


Thanks again


Cant wait to try it out

Posted by: r_towle Aug 1 2012, 04:03 PM

Take a look at the Tps switch...it has 20 or so different contact that the fingers ride along, this determines the fuel duration.
A loose finger or inconsistent contact will make the wcu go from position x to idle and back again...
Idle is a non contact area on the middle finger

That is how I figure it's doing it, but I am sure someone will correct me.

Posted by: The Cabinetmaker Aug 2 2012, 08:43 AM

Well? Whats the verdict?

Posted by: jsayre914 Aug 2 2012, 10:33 AM

Runs like a champion, no bucking at speed and smooth accleration. It pulls like a roller coaster


Thank You

Posted by: Vacca Rabite Aug 2 2012, 11:05 AM

?

Posted by: The Cabinetmaker Aug 2 2012, 03:33 PM

You are most welcome. thats why we're here.

Posted by: jsayre914 Aug 2 2012, 03:36 PM

Working sucks

I wanna drive !

Posted by: jsayre914 Sep 9 2012, 12:34 PM

Just to follow up, I sent my orginal TPS with the new board to Dave Sprinkle. He checked it out and found that corrosion on the two upright post on the arm itself was prohibiting the TPS from making a good connection. He sanded it and mailed it back to me, I swapped it back out with the one that was working fine and now BOTH are working fine.


THANK YOU DAVE !!!

GREAT PRODUCT !!

and he took care of my problem in a timely way, even called me to follow up today

Posted by: davesprinkle Sep 9 2012, 12:46 PM

I contacted jsayre regarding the behavior of his TPS with my replacement board. He sent me the TPS and I debugged its problem. The issue was corrosion on the post in the shaft of the sensor, which prevented a good connection with the leaf-contact and would never allow the sensor to detect the idle position. I dragged some 2000 grit sandpaper between the contacts. According the jsayre, this fixed the problem. I've attached a picture of the post and the leaf-contact.


Attached thumbnail(s)

Posted by: rdauenhauer Sep 9 2012, 01:49 PM

Great thread!

Posted by: toolguy Sep 9 2012, 06:56 PM

Wow. . what a difference friends make. . that's a whole lot of good Karma going on. . . this is a great site. .

Posted by: 76-914 Sep 10 2012, 02:22 PM

True, the people on this site regularly expose themselves for the "good Joe's" that they really are.