Throttle Sticking - any ideas for fixing?

[tony-baroni]

TPS info
Tunerpro RT plugged into vehicle, looking for connection.
Turn key to ON.
TPS voltage displays 0.5, frequently switching between 0.4 and 0.5
TPS throttle position % shows 0% initially, but then starts creeping up, gage moves up/down by a few tenths, or points...after a minute it's fluctuating around 3-4%, wait a bit, now it's steady at 5.1%

Then V drops to 0.4, and TPS% fluctuates between 3.9 and 4.3%

pedal to floor, shows 4.6V, 100%
release pedal, shows 0.4-0.5V, 3.9-4.3%

Tapping throttle, not exceeding 10% throttle position, and V varies/jumps between 0.7 and 0.2V, let it sit.
V stabilizes between 0.2-0.3V, TP at 0.4-1.6%

Pulled doghouse, and unplugged TPS from harness. Connected tunerpro, and switched key to ON, engine still not running.
TP5 reads 0.0-0.1V, at 0%TP
TPS sensor is rigidly attached to TBI as I expected, no movement there.
Plug in sensor to harness, V jumps to fluctuate between 0.3 and 0.5V, and TP% jumps right up to 5%, and fluctuates.
I find that I can tap on the sensor itself, and the reading fluctuates. Is this typical with the sensors? I've got two from my mod'd TBI provider.

Also, I am getting continuous TUnerPro fluctuating between DA: Connected, and DA Data Error!

Any ideas on why that would happen as well? I've tried various USB ports, and it behaves the same.
I also tried turning OFF the connection within TP5, then turned off key, flipped TP5 connection on (status DA:Connecting...), and then turning key ON. No connection.
Toggle the connection on/off, no change. Had to reboot TP5 twice to get a connection.

[lionelhutz]

Bore for the throttle shaft worn out so the shaft has play in the hole? You can find bushing kits fairly cheaply if you search Ebay.

[tony-baroni]

Throttle shaft is a-ok...the TBI is as new - from SPR performance. Super smooth, no friction or binding.

[lionelhutz]

OK, didn't see it mentioned in your posts. It has to be a mechanical binding of some sort. The vacuum might be pulling the blades in the direction to cause a bind.

The TPS should not cause it if it's properly installed. The MAP sensor can't cause it.

[tony-baroni]

It is puzzling...I like where you're going with the vacuum pulling blades in a particular direction. I can't feel ANY sticking when moving the blades or the cable attaching bracket. I have taken a bunch more video's of diagnosing this...and will update with new links when I get them up on youtube.

FYI, I also had the throttle cable inspected by a mechanic back when it first occurred. I also checked it when I first had this problem with the new rebuild. There is no stiction in the cable.

[tony-baroni]

My continued chasing a root cause has uncovered what appears to be three issues.

1. Throttle blades intermittently sticking OPEN when engine is running, clearly noticeable w/o load, haven't noticed while under load.
2. Intermittent issue with voltage output from TPS, being disturbed by tapping, moving wires on harness, and sometimes the voltage dropping to 0.2-0.3V. other times it works great.
3. Intermittent issue with throttle position percentage, rising above 0, to as high as 8%, and staying there, when the throttle has NOT opened, and the TPS voltage is performing properly (~0.5V).

Regarding throttle blades, the video's linked earlier in the thread show this in action. Still looking for a solution.

Regarding intermittent voltage output from TPS, my first thought is a bad TPS, however the symptom is intermittent, and the symptoms re-occurred with a new TPS sensor, I think it's something else.

Regarding the throttle position percentage issue, I think this may be a fault ECM issue.

Here are some video's showing this odd behavior.
https://youtu.be/qaS7B4cauSM

The manual diagnostics requires a scan tool, which I don't have. I'm looking for some guidance in troubleshooting the root cause of these issues, and fix them, before I start tuning the engine/chip.

Here is what I did to start troubleshooting.
Test sensor values going INTO the ECM at the connector (sensor is working properly in this one)
https://youtu.be/Hf6qk8nx4gI

Confirm the ECM input pins, match the output from the ALDL cable. (sensor also working, but TP5 connection errors)
https://youtu.be/cypYZXFOZkU

https://youtu.be/f7A9RTLiXJU (same, another test, working this time)

[myburb]

As posted earlier I think you need to address the sticking throttle. It's got to be worn throttle shaft bushings, misinstalled throttle plates or throttle cable interference. I know you said they were good but??