TPS, what a difference a fraction of an inch makes!

[Guest Bagheera85]

Ok, so I cleaned and adjusted my TPS today. And I must say, adjusting it like the Haynes manual says, it makes quite the nice difference. Doesn't do that stupid shift, then lag, then pick back up thing anymore. And it shifts more.. correct now. Just plain feels better.

[Guest Sydfloyd44]

What exactly did you do in the adjustment process?

[Guest Legacy777]

YES, do tell what that haynes manual says. Chiltons was smokin crack when he wrote mine up on adjusting the TPS.

[Guest CipeR]

I think I know how to adjust this. This knowledge was gained on Toyota's but is applicable.

 

For most functions it doesnt matter WHERE THE SENSOR IS LOCATED.

 

The important one is the idle position lead. When the throttle is closed it will be no resitance, with it open a small amount it will be infinite.

 

This will effect alot of things, depending on how the computer is designed. My legacy would act funny with shifting, and it would jerk sometimes when coasting until I adjusted it.

 

First you have to figure out which wires control the "closed throttle" portion. Remove the sensor and measure it. Once you find the right one (on mine i think it was the first and last connector).

 

Now place a dime in between the throttle screw and the throttle. with this much space the sensor should NOT be active. running all the way through the throttle range should also have no effect. When the throttle rests against the screw with the dime removed it should be connected.

 

That is the correct way. The service manual probably specifies a certain feeler gauge to use but a dime is almost dead on.

[Guest Bagheera85]

Ok, with the throttle closed, you should get 0 ohms resistance on terminals 1 & 2. Term 1 & 2 are the 2, on the left, next to each other, when the 3 plastic 'prongs' are pointed towards you(this should put you on the pass side of US cars). When the throttle is completely open, there should be infinite ohms. Now, stick a feeler guage of .028 in between the throttle stop screw, and throttle stopper. You should have 0 ohms. Put in a .035inch feeler gauge, and you should have infinite. If this is not correct, turn the TPS slightly(as in just barely bump it, screws loose), until the ohmmeter goes to 0. Test again until you get it right.

 

And have fun!

[Guest Legacy777]

interesting.....I'll have to play when I get to Houston....cause I don't have time now....damn packing. Where's that transporter beam when I need it.

[Guest unobtainium]

Every time I see nicely-written instructions like that I want to cheer - and go do the work right away. Thanks, Bagheera.

[Guest CipeR]

Isnt that what I said?

[Guest st2eelpot]

Ciper- Yes, I think that is what you just said. The only difference is he had term numbers. Though for the record (bored at work with a dime and some calipers) it looks as though a dime is around .045 inches thick, so that might be a bit much... though I don't remember the last time I got anything to .001 inches specific anyway.

 

just poking fun, no offense intended.

Cheers,

Dave

[Guest Bagheera85]

It actually does seem to matter, in other than idle position. I don't feel as much lag during certain condition shifts as I did before.

[Guest OutbackKY]

<<...Term 1 & 2 are the 2, on the left, next to each other, when the 3 plastic 'prongs' are pointed towards you(this should put you on the pass side of US cars). ... Now, stick a feeler guage of .028 in between the throttle stop screw, and throttle stopper... If this is not correct, turn the TPS slightly(as in just barely bump it, screws loose), until the ohmmeter goes to 0. Test again until you get it right. >>

 

I'm trying to follow along. When you are testing the terminal, you're talking about on the sensor itself, not the wires/connector that snap onto it, right? The throttle stop screw and throttle stopper are on the other side of the block, opposite the TPS? What cleaning was necessary on the TPS? Does all this require you to open the TPS itself?

 

Thanks in advance,

Bryan

[Guest SmashPDX]

This thread is archive-bound when it's done (I know it's not done yet). Somebody tell me when it's done so I don't forget

[Guest Bagheera85]

Yes, the TPS itself, not the wires. The stop screw is opposite the TPS on the throttle body. The throttle 'stopper' is what hits the screw, and is attached to the spring and throttle cable.. that whole little contraption.

 

As far as cleaning, no I did not take it apart. I took it off(watch the screws, I lost one to the great abyss underneath my intake manifold), and sprayed electronic cleaner into the small holes in the plastic it has. Then I sprayed some electronics compressed air duster in it to dry it out some, followed by a little bit of time. I then put it back on, and adjusted it properly. Hope that answered all yer questions.

[Guest shortlid]

I have a '88 camry that is doing the shifting weird thing. What year and engien did you do this on??

[Guest unobtainium]

That really makes a night-and-day difference in how my car runs. No more rubber-banding at 1500rpm.

 

For those without manuals:

 

[Guest CipeR]

Dont forget to clean the connections along with the internals. An emory board helps to clean them up.

 

If these are adjusted correctly when the car is new, and the idle screw hasnt changed how to do they get so far out of adjustment?

[Guest Bagheera85]

Electronic components can fade over time, especially when subjected to such temperature extremes as an engine. Look at a light bulb.. it's just a resistor that glows with enough current flow. Eventually, the heating and cooling fatigue the metal and it breaks. As metal fatigue sets in, resistances change. Therefore, you have to adjust to compensate.

[Guest CipeR]

This isnt the cause for the tps. The only reason it needs adjustment is to get proper reading from an on/off based idle switch.

 

The resitance portion can vary wildly from part to part. The important thing is a steady increase/decrease when the sensor is moved.

 

Judging by the readings I took of all the different terminals it looks like the computer might be able to see total resistance and compare that to the reduced resistance the sensor is giving at a specific point. With the self tuning its able to pretty acuratly tell what percentage of WOT you are at.

[Guest Legacy777]

Ciper's right about the wild resistance. My TPS was not really close to what the book said it should be. It seemed to be fairly steady, linear response. I will have to check out the stop screw and IAC valve thing though.

 

The ECU must be able to translate where or how the TPS reacts or something....beats me

[Guest PaganQWA]

Id like to do this but I'm still a little fuzzy on some things...

 

How do you know when your multimeter is reading infinate Ohms? I'm still learning this funky tool

 

Where do you put marks on to line it up when you want ot put the TPS back on after cleaning it?

 

Think I could do this in my 1 hour lunch break?

 

Thanks!

[Guest Legacy777]

you see where the two screws are, and the outline of the sensor....sorta take a scribe and etch in the metal where the sensor bracket was and such.

 

I'd suggest spending more then your hour lunch break. It would be VERY VERY close....and that would be if you knew exactly what you were doing.

[Guest CipeR]

Infinite ohms means no conenction. The same reading you get when the meter is off!

 

The marks you can put where ever you want, they are for your future use so you can get it in the same place again. Actually Id suggest not marking it. Any time you remove it you should readjust anyways.

[Guest Bagheera85]

But if you want to mark it.. white out is good.. that's how mine is(but I think with a paint marker). From the factory, or the dealer.. the TPS was marked across the screws, along with the IAC motor and throttle stop screw.

[Guest PaganQWA]

Ciper: Um when mine is off id displays nothing! I have a digital multimeter. Would infinate Ohms be the same as if having the meter set to read Ohms but the probes are not touching anything (i think it just reads a 1 then)

[Guest Bagheera85]

If I remember right, they will read 1 to indicate infinite.. and just 1, not 1.0 or anything.. you can always test it.. by putting the two ends on a piece of wood.. cuz it won't conduct.. and that is what infinite ohms is like..