Throttle potentiometer, test passed?

[dkw_dude]

Did a test on my throttle potentiomer as described on this brilliant website

http://s2central.net/ds_F60_G69.html

Test was passed exept ohm value between pin 2 and 3, according to the test it should be approx 3600 ohm, on my pot. I measured it to ~2600 ohm, not good.

But I think I have seen somewhere that the barometric pressure sensor is connected in series with the pot, an then the reading should be ok I think.

Maybe someone can eventually correct me on this, or confirm that it's right? I don't trust my memory 100% on this one!

[Graham]

Dont know if it is a similar problem, but i had a problem with my golf where its tickover was lumpy and it used to pop and crackle decelerating , i done a test on the potentiometer and the output voltage was IIRC supposed to be between 2V and 5 V, the further up the range it went the higher the voltage (and revs), but between tickover and 2000 revs the voltage was jumping all over from 0V to 5V, and was very erratic. Phoned the stealers and they quoted me £460 as they would only sell me a complete throttle and potentiometer in one piece so i stripped it all down one morning and removed the securitorx which VW put in to stop people sussing the problem and looked at the potentiometer contact face, all there is in them is a wiper arm rigidly attached to the throttle shaft (so as you squeeze the throttle the wiper sweeps across its range) and on the wiper is a set of three or four contacts. The contacts mate up against the potentiometer face which consists of a carbon coated face where the carbon is set on like an element as can be seen below. The carbon element is about 5mm wide all the way round but the contact pointers are like pins so they only touch a tiny area of the contact face. On mine the first 1000 revs (1K-2K) was worn out where the pointers had gouged the carbon off the face over time, but the rest of the face (the other 4.5mm ) was fine. So as the bolt holes which hold the potentiometer to the throttle body were slotted axially i just turned the potentiometer a degree to put the contacts onto a new part of the carbon face and Presto £460 saved and it has done 14K miles since i done that.

[dkw_dude]

Thx Graham, nice solution to that problem

Don't have those symptoms, I have the common hesitation and the car sometimes doesn't want to WOT (losing 0,2-0,3 Bar) have checked out most options and thought I was going to give this a try. And then discovered that the ohm value for pin 2-3 was not right.

Had a look here
but couldn't find specific values for my TPS, nice book on Bosch fuel injection in general though.

Checked out the "family album", TPS part no. for 3B is different from ABY. Then maybe my TPS is ok, wasn't erratic at all when I did the measurement, smooth increase from min to max ohm.

[audiman]

Those values are only approx values, virtually no two sensors measure the same.

[jameswkr]

When I was chasing a lack of boost, I measured a similar value on full throttle.
PN confirmed it was the "relative" value that was more important, so I went looking elsewhere. Make sure its adjusted correctly so that the idle switch just clicks as the throttle finally closes and that the damper is also correctly adjusted.