TPS fluctuating, idle problems.
 

I have adjusted my TPS to ~1v DC with engine warm and key on, and set idle and it was fine. The next morning I check TPS on my Rtek and it has changed, and in turn my idle has risen up to about 1100. I have swapped out another S4 TPS from a forum member and it did the same thing. Both TPS's sweep from ~1ohm to ~5ohms, but if I let the plunger out quickly on both they will show a 0, then quickly jump back to ~5ohms. My Rtek 2.1 shows the TPS in a % value, and I set it to spec which is 20%. Then today it jumps up to 26% which I assume is why my idle is off.

Do I need a new TPS? Or could this be something else?
My Car is the 10th AE in my sig.

yea, that doesn't seem right. I know mine goes to 0 when alllll the way in, but, with the gas pressed all the way down, the plunger never goes all the way.

Also, are you using a DMM? If you use an analog, you should be able to see it sweep back. Sometimes a DMM will get confused if it goes from like 5k Ohm to 1k Ohm. And, it will take it a second to figure things out. Use an analog MM if you really want to check the TPS thoroughly.

My, my.

Anytime the throttle linkage moves, the TPS value changes. That's a given and I'm sure anybody/everybody knows that.

You get the engine HOT before setting the TPS so the waterthermowax will fully extend it's piston and drive the cam off the roll pin. See the FUEL AND EMISSIONS section of the onlne FSM if it's not known what the waterthermowax/cam/rollpin are. They're shown in a picture.

So. You set the TPS with a fully hot engine. The cam is off the roll pin and the trottle linkage is fully CLOSED, because the engine is HOT.

The car sits overnight or even for a couple of hours. The waterthermowax's piston retreats into its housing. The cam and rollpin engage again and the throttle linkage MOVES to open the throttle plates a bit.

When that happened, the piston on the TPS moved. Now the output value of the TPS on your RTEK should read a higher value than it did after you set it when the engine was HOT.

Now you start the engine and get the engine hot once more. The value on the RTEK comes back to its value where you set it the other day. It should read approx 20% on a RTEK, which would be an output of one volt dc if you looked at the green/red output wire on the TPS plug or at the ECU.

The rpms should read approx 1100-1300 rpms when the car is started up, and decrease to approx 750rpm when fully HOT. Normal. That's the way it's supposed to work. The waterthermowax/ fast idle cam/roll pin are what cause the 1100 rpm idle. The TPS HAS ZIPPITY TO DO WITH THE IDLE (on the whole that's true).

Again, this is NOT a *fly by wire* system with a mechanical cable backup. You move the throttle plates using the cable connected to the foot pedal...then engine gains rpm. NOT done by the TPS output.

Thank you for clearing that up.