Sigma 125 TPS setup.

[nickhi]

I am trying to diagnose/check my Throttle Position Sensor, I have searched Blatchat but can't quite seem to find the info that I think I need relating to a Sigma 125 2013 vintage, standard single Throttle Body. I have a little problem when the engine is idling, applying the throttle pedal the car seems to stutter and kangaroo momentarily resulting a bit of a jerky moment. Once the pedal is pushed a little further it seems to be fine.
 
So I have been looking at the TPS using Easimap and monitoring the Throttle Site and Throttle Angle and trying to figure out if these are correct.  I am no expert in this so apologise for my potential numpty questions. As I understand it the TPS is basically a variable Resistor and the ECU measures the voltage at the wiper which essentially gives the Throttle position (I believe this is the Throttle Angle in Easimap). This is then related to a Throttle Site.  So using Easimap with ignition on but car not running I seem to have a Throttle Angle that seems to flicker between 0.4 and 0.39 (occasionally 0.41). This then seems to result in a Throttle Site flickering between 0.1, 0.5 and 1.0. I have also noticed that the Throttle Site can flicker between 0.5 and 1.0 without the Throttle Angle voltage changing.  I have also managed to get to Throttle Site 0.0 (Throttle Angle indicated 0.39) momentarily.                    

My question is, are any of these numbers/readings correct. If not does anyone know what they should be so that I can possibly adjust the TPS so that I am in the right area. I suspect that the TPS needs replacing so any setup info would be most helpful.

Many thanks.
Nick

[Tom_Arundel]

TPS is VERY sensitive to position at closed throttle and is difficult to get right.

The `dithering` seems a bit much but they all do it to some extent. Check all relative loom connections

Throttle should run 0-15 on the sites and go fro 0 to 1 as soon as throttle moves

All you can do is adjust by VERY small amounts until you find what works.....It`s not far away

DO NOT over tighten the 2 screws holding the TPS as this can cause the throttle to stick wide open!!

Check rubber pipe to manifold pressure sensor for leaks/splits

This type of TPS is generally reliable....how many miles has it done?

[nickhi]

Hi,

Thanks for the info.  Car has done just over 14,000 miles.  I checked at full open throttle and the site read just on 15.2 so I guess I have the full range ok, but as mentioned maybe just a little tweak at the low end to settle things and hopefully stop the 'dithering'.  Thanks for the note about not overdoing the TPS screws. 

I can't see any splits in the hose, but will probably replace as it's an easy maintenance job. Any recommended source of pipe?