Hey,
I've got an 02 neon - vanilla SOHC, automatic.

I just recently got an ELM327 interface, and hooked it up to the lappy computer... and discovered the ECU reports absolute throttle position at 12.5%, with my foot off the pedal - and up to about 78% with it floored.
Why?

Today i just yanked the intake box and investigated.
I pulled off the the TPS, turned on the ignition so the computer was on, and it said something like 3.5% - then i turned it with a screwdriver, and it went up to like 93%... which is way more than when it's installed and at wide open throttle. But it still isn't zero to 100%.
Whats the deal?

Does anyone know about this?

Is there a way to calibrate the computer with the sensor so it sees 0-100%?
I think this is affecting shift points considerably...

(As an aside: i screwed with the IAC electrical plug, and the engine went "puke bog die", and the meter said zero voltage on both wires, wont stay running -- and then suddenly it's ok again?!... pretty sure it's a wiring issue. And it looks a bit gunky on the valve plunger too.)

 

What makes you think those reading are out of tolerance ?
Computer likely calculates ATP using more data points than just the TPS position.
This is a complex closed loop feedback system and what you are observing could be perfectly normal

 

Well - it's not a question of "out of tolerance" - and don't think there's anything complex about it. As I understand it, that figure is a percentage, intended to represent a physical position of a mechanical device.
Q.E.D.
It's not "virtual throttle position" is it?

Every other vehicle i've plugged this onto has reported 0-100% throttle position just fine.

I reset the computer several times, and polled this value without starting the engine. Same result. 12.5% to 78 or so. I don't know of any calibration procedure - i'm no guru dodge technician, or whatever.

My best guess at this is sloppy firmware programming.
Any programmer worth his wage should be able to figure this out.
1. What's the voltage at closed position?
2. Write subroutine to monitor this and store value in non-volatile memory.
3. What's the voltage at Wide Open Throttle?
4. Write subroutine, etc...
5. Write simple formula to calculate throttle position: (Current value - closed value) / (WOT value - closed value) * 100 = ATP in percent.

It's not "sensor voltage / reference voltage = throttle position"... which is what appears to be happening here.

Anyways - I know the computer can work around this, with the o2 sensor, etc. That's the "complex" part of it.

As for my comment about shift points, i think there's something else going on. It's a torque issue. I hear a faint "zzzz" pinging noise, at partial throttle.
Tried higher octane, and it lessened a bit, but didn't stop.
Not sure what it is yet - bad knock sensor comes to mind?