6n1 Throttle body questions

[pontiff]

All,

Just a few questions regarding the throttle bodies on the 6n1. I have (yet another) automatic 6n1 which has erratic idle. Using vagcom I have checked the fault codes and have ran a throttle body adaptation run. It does not complete as when it is stepping back to its closed position it gets 'stuck' and just sits there whirring away. Trying a spare throttle body that I have fixed all the problems as in the adaptation run works fine and the car idles just fine which leads me to saying that the throttle body is faulty.

Okay... not that I 'need' it working as I have a spare but I am curious about why its not working correctly. Googling around as one does, i have given it a good clean as while it was not clogged it had a little bit of gunge on it so after doing that still no luck. So i removed the back housing and checked for anything out of the ordinary in terms of dirt and what not in the electrical mechanism but it was all okay as far as one can see, the range of motion of the unit is full and without impedance so i gave it a spray with some electrical contact cleaner anyway and put it back together but the same issue remains. The manual side of the throttle works fine as in the cable that's connected to the throttle pedal ranges the butterfly across the full range so for some reason the electrical idle side must be faulty.

Has anyone investigated these throttle bodies before in terms of the electrical side of things? There is a lot of info around cleaning the butterfly and what not but not much around why the electrical side fails. I would not be so concerned if the electrical side did not work at all, but it completes about 80% of the test and then fails, so its not like the actuation does not work at all... weird.

Then it comes to the part number... the part number on the unit is 037133064F, ETKA (numerous sources) say that It should be 037133064E. I know that people say that they are indeed different (and even 037133064D gets a mention) but i have honestly replaced about 4-5 of these now and i always just replace it with whatever number I have around which is mostly D but have replaced an F with a brand new D before and they always work just fine so whatever difference is, it does not appear to affect the long term operation of the car in terms of idle or power. The question I have is around what 037133064F actually is and why ETKA would not list it anywhere. I have had a polo that I have known from new and the original throttle body is an F even though as I say, ETKA says E is the correct one... Has anyone managed (or cared) to work out what the discrepancy is? D also appears to be cheaper than F to buy.

TLDR: throttle body part numbers dont match ETKA and has anyone worked out why the electrical side of it fails.

[Umai Naa!!]

Not 100% familiar with the throttle bodies on these, but what are the chances of say, an air leak in the unit itself, causing the erratic idle?

Perhaps it leaks at the linkage end of the shaft?

Or, maybe there's oil breathed from the crankcase entering the elecronic side of it, again, via the shaft? This in itself, will cause issues.

Only mentioning these examples, as I've seen both on other makes and models.

[Jmac]

Reasoning for me would be a superceded item, they are both cable type, and they are compatible with auto and ac both which have idle up. Be interested to see you use a second handie, in my minds eye they should be the same.