How important are perfect idle TPS readings?
 

I have another thread regarding my truck running rough and sometimes dying at idle or when accelerating from a stop sign.

Alternator brushes and TPS are suspect. Want input before buying a new TPS because it's somewhat pricey.

I have been adjusting the TPS per 4crawler instructions and the best I can do is:

Closed throttle 4k ohms,
.5mm feeler 5k,
.8 feeler OPEN

or

Closed 600, 2000, 2400

I can't get it to read around 2000 (or lower) at .5 and open at .8.

Anyone have experience with this?

It has a bit of an error margin, the less than 2500 Ohm. May not be obvious but it's much easier to inspect the TPS if it's not attached to the throttle body, With the TPS in it's home position you should have near zero resistance between Idle and Earth, higher Ohms here give an idea of the sensors age due to the crud on the wiper. If the resistance is over ~2k it's really old, shorted, or other wise just time to r&r.

What is that second bit, is that with the sensor rotated fully to the front(CCW)?

It's the original TPS as far as I know so maybe it's just time. Do you think the reading being off by that much is enough to cause it to run rough and sometimes die at idle?

The second set of numbers is just what I end up with if I adjust it so that I have around 2300 ohms with a .5mm gap.

Seems like my two choices for adjustment are to target barely OPEN at .85mm gap, or ~2000 ohm at a .5mm gap.. following the 4crawler specs. The problem is I can't have both, so I probably need a new TPS, but I do wonder if that alone is causing all of my idle problems. Seems like it's running worse than I would imagine but I don't have any experience with the how much someone can gain by replacing the TPS.

Interesting note- I tried running it with the TPS unplugged and it still pops and missed although at a higher RPM.

Perhaps my problem lies elsewhere (or there are multiple problems. Likely..)

I've read reports of the ECU using some "at start up" calibration for the air meter, let's assume it does a similar check on the TPS when it is powered on and it sets the low throttle point. In that case you want as much available signal as you can get to Vta with IDL disconnected around .7 or .8mm. iirc the IDL section is about 10k ohm long.

The air meter is constructed internally similar to the TPS and has the same wear issues, resistive material abrading off the board and onto the feather contacts.