Hi Everyone. I'm playing around with my 74 2.0 liter trying to get it to run a little better. It "bucks" occasionally so I was looking at the TPS yesterday. I couldn't get the TPS off to open it up,I think there may be locktite on the screws and I was afraid to really reef on it!! But I did try the 20 click test,but I heard no clicks. None!! What does this mean? Is the TPS not functioning at all? What would that do for driveability? I don't have much frame of reference as this is my first 914, but the car does seem to exhibit the ususal TPS problems. That is...it bucks, and the acceleration is sluggish.
Any and all comments really appreciated!!!
Cheers
Mike

Before you condem your TPS I would check the wires and make sure that they are in good shape. One trick to check your FI system is to remove the connector for the "brain" and use an ohm meter to probe your components. DO NOT probe the brain--just the components.
Check this out: http://members.rennlist.com/pbanders/djetparts.htm

Good morning, the 20 clicks you are trying to hear are your injectors not your tps, as the tps wears its internal armature drags across a internal printed circuit board and creates a groove in which little tiny specs of gold from the contacts get dragged in the groove and then this wear groove starts to make a connection between 2 of the contacts and when your armature (throttle) comes across this worn in unintend connection between the 2 contacts the TPS sends a confusing signal out to the ecu and the bucking starts.

good news is you can now get a new printed circuit board for the tps for about $35 and install it your self, but you have to get the tps off the throttle body..

someone will chime in wear to buy them,...

your can take the cover of the tps off without removing the tps, but it is easier to unscrew the 2 screws, sometimes screws on these cars can get stubborn, you can replace the screws but don't stript the threads on the throttle body...

bucking is common for worn tps..

here is the article on how to re-install the tps w/ proper calibration, whihc is really just the angle you screw it down so the interal contacts start at the idle position..

someone may provide a pic as well..

http://www.pelicanparts.com/techarticles/9...alibrate_20.jpg

Click to view attachment

Just to be clear...you are saying there may be problems with thw engine wiring harness? Is that common? I'm just trying to get this car to run a little better.
It doesn't "pull strong" like others cars seem to!!
Mike

Dextocowboy...thanks. I have those instructions from Pelican but couldn't get the TPS off the throttle body. The angle at which it is attached would make it very difficult to work on still attached I think. I just don't want to turn those screws too hard and break something.
Cheers
Mike

you do have 35 year old wires in the car. The symptoms you describe are indicitive of a bad tps, but I feel it is prudent to check all of your components. It does not take that long. Then you can go about fixing your issues...

yes, getting it off would make it easier to work on, if you cant turn the screws with a screw driver, take a pair of pliers or something that has good grip and some leverage, you can replace the screws they are m4x6 i believe.. i would says use some heat but the tps could get hot, not good..

One of the things that I found was that the wrong way to do things was to adjust things and then replace the harness with a Bowlsby harness. I should have done that first. I had things running as best they could and then replaced the stock harness with a Bowlsby harness only to find that all that fiddling to get things set perfectly was only compensating for the ills of the old harness and weak components. I had to restart all the fiddling around when I put the new harness in. Should have started there.

40 years of corrosion and broken wires will screw up everything you are trying to do. Those Keyser/Bowlsby boys make a harness that is well worth the money...

I bought Jeff's harness first then replaced everything, but might as well take a look at the tps circuit board, replacing it is only $35 and if that fixes what ail you and your satisfied then great!! If not then you may want took take a look at the wiring and fix or replace before you hunt down and pay for potential causes, bucking is common issue tps especially at low constant speeds..

Ie: what he is saying is that if you phone calls keep getting dropped or poor connection buying a series of new cell phones won't fix the problem you need a new carrier..

I have mine unplugged now and it runs better. I would rather have it functional, so where can I get a new circuit board for a '72 1.7L?

Thanks!
BK

find Dave, davesprinkle, is his user name on this and the club site

Thanks for all the comments. I think I'll try again to get the TPS off to have a look at it. Then maybe look at the wiring harness if my issues are not solved. I'll contact davesprinkle about a new circuit board if mine looks bad.
On another note, I recieved and installed my Triad muffler. What a nice piece of gear that is!! It looks like a piece of art and the car sounds great now.
Just a little plug for Tiad there....
Mike

Found him, thanks!! Have one on the way.

i have a question about the TPS. general question that i couldn't locate an answer for anywhere.
if you set the tps further than 'one more click' what happens?
it seems that it would force it to think throttle was in a completely different place but which direction and what does it cause? i may try this next time i get out to the car if no one has an answer like 'i did that once and this happened'
theory is great but i want someones first hand experience if possible.

thanks

Mipstien...that's a good point. I'd like to know what happens if you try that!
I tried the 20 clicks test but heard NO clicks...what does that mean? What kind of driveability issues will I have with a TPS that doesn't make the injectors CLICK?
Mike