General TB opening 90% ?

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General TB opening 90% ?


VW Polo 1.9 TDI Sport
Dec 9, 2005
I've just fitted a new custom 38mm TB which is great.

But when I get someone to put the pedal right down it doesnt seem to open the thottle fully, I cant turn the plastic bit about anouther 10%.

Are there any adjustments i can do or is it ment to be like this?

Looks like i have to adjust the two nuts?

I didnt think this would make a difference since the cable was inside it :confused:
yep you adjust the 2 nuts, 13mm spanner (i think)

1 way will make it slack the other will make it tight

i think i remember reading there needs to be little play with the cable when you pull it

have you tried opening the TB 100% manually, maybe it stuck or something
Is the flap inside the TB totally vertical to the 90 degrees position, with the pedal to the floor? Then it's ok. It's also ok to move another 20 degrees past the vertical.

If it's not, adjust the two nuts, so it becomes totally vertical when pedal to the floor.
I've taken up most of the slack, feels a lot better now on the pedal and seems little nippier.

Havn't checked the butterfly yet, but its as much as i can adjust it without it pulling the thottle open.
rallycinq said:
I think you might have to back it off a little bit, you need a bit of slack. In general, you don't need it absolutely vertical.

Yep, the 32mm TB I have in bits here has 85 degrees stamped onto the butterfly...Id think that means its designed to run over a 85 degree range from its neutral point (which isnt a perfect horizontal!)
Yeah i'll back it off a bit

Was idling at 1000 so i think it must be pulling slightly

I'll give it a little of slack