Mi16 Lower Throttle Butterfly Not Opening Fully

[Powers 13]

While adjusting the TPS (on or off) on the throttle body i realised that the lower butterfly didnt open fully.

Is this normal, to induce swirl and turbulence in the chamber? Or is it that the nylon rod on the linkage warn?

Cheers.

[Sandy 191]

IIRC the Mi16 linkage opens both simultaneousl, but the 405 8v linkage is two stage. I fitted the two stage to my first Mi16 and enjoyed improved economy as a result, because I tended only to push the second open deliberately!

[KRISKARRERA 2 1 Cars]

You might have the 8v throttle body fitted but what exactly do you mean when you say it doesn't open fully? If it's about 2mm closed more than the other one that's just normal.

[Powers 13]

The top butterfly opens at approx 90 degrees (WOT) to the direction of air flow, whereas the lower one is about 75 to 80 degrees.

 

Just checked and they are simultanious, however the bottom butterfly only begins to open when the top butterfly is around 10 - 15 degrees open.

Edited October 13, 2006 by Powers

[Sandy 191]

Slack in the linkage by the sound of it, unlikely to make much difference though.

[pug_ham 244 3 Cars]

I've recently rebuilt two Mi throttle bodies & they had the staggered opening where the top butterfly opened to about 60' before the second one started to open, at full throttle both were fully open.

 

I'd suspect the same as Sandy that the linkage needs adjusting.

 

There are at least two makes of TB & some of them only open both butterflies together, not staggered.

 

Graham.

[ada205 2]

I've got a complete inlet mainfold off a 1.9 Mi at the side of me now, as you do, and both butterflys open simultaniously, though the top one connected directly to the linkage starts to open a tadge earlier, but probably due to linkage just being old and worn. Both look cock on 90 degrees at full throttle.

[Powers 13]

Thanks ada205 thats exactly what i wanted to know.

Now all i need to do is adjust/ rebuild the linkage.

[KRISKARRERA 2 1 Cars]

Can the linkage be adjusted though?

[pug_ham 244 3 Cars]

Can the linkage be adjusted though?

Not on the ones I've seen, either they open staggered or together & there isn't much to adjust but if the linkages are worn they can stick which could be the problem here.

 

Graham.

[KRISKARRERA 2 1 Cars]

Yes I remember Jackherererer talking about worn linkages and needing a new TB. I wonder if Weber or Pug still sell them.

[C_W 3 1 Cars]

Will be mega bucks for one though I bet. I think its a nylon bush on the pivot point of the linkage that might wear (or even break up and fall out) meaning it doesn't open as far as it should.

[Powers 13]

Cheers for the replies. It is the Nylon rod that is worn on the linkage. Unfortunately i will have to strip it down inorder to change it. Oh well, best get on with it.

[C_W 3 1 Cars]

It may be possible to bend the pivoting lever? or pack it out with something??