Mixture Screw seized

as above really, the mixture screw on my GTI has been seized since I've owned the car, I've sprayed WD40 in there regularly for a few weeks now but can't get the thing to budge, don't want to be over zealous and end up damging the screw or breaking something. anyone get any little tips to free it off?

Plumbers pipe freezing spray may break the bond and also try plusgas,it penetrates a little better than wd40, make sure you get a really good quality allen key and it is in really well before trying to move the bugger!

how far down is this screw?i dont know if mine is missing one? when i put a screw driver in  it seems to go really far down.is the screw on something else inside the metering head?

its really deep inside the assembly, its actually a 3mm allen key if you didnt already know this.

you can take the air flap assembly apart, its fiddly but doable. once you get the arm out you can then get some mole grots on the screw to gently crack it loose, if buffing it with a wire brush and penatrating oil doesnt help

ah right i see.my cabby runs fine but has a slightly rough idle.i sprayed contact cleaner down that hole where the mixture crew is and the idle leveled out.does this mean its deffinetly my mixture out?

Have you checked your exhaust gases on an analyser? That's the only way to tell for sure if your mixture is correct.

When I got my Golf I thought it was running a bit rich, but in fact it was lean. The ignition timing was also out (too advanced) and the cam timing was wrong too - out by 1 tooth so retarding it slightly.

Not trying to worry you, but now those 3 things are sorted it runs a lot more smoothly, pulls more strongly, especially at low revs and idles nicely too, when it was a bit rough before. In short it has transformed it!

It doesn't take long to check with the right tools so might be better to get a garage with the right kit to make the checks for you (although you can check the cam timing easily enough yourself - there will be a thread somewhere on how to do it)
Hope this helps

Mike

ah right ok.my manifold is blowing slightly so i dont think that helps the idle.it pulld nicely through the gears tho so i dont think the timing is out.and it starts first time with no trouble.shall i try the mixture first then try something else?thanks for your help

It doesn't sound like there is much wrong with it then! I wouldn't advise fiddling with the mixture yourself in any case without a gas analyser.

The emissions check for the MoT is effectively the same as the check you would do to check your mixture - if your MoT is due soon then maybe get them to check and set up at the same time if necessary?

An ignition timing light is about a tenner on Amazon - instructions on how to check in the Haynes manual so you might want to have a look at this. Also make sure all of your thin vacuum pipes from the inlet manifold to the distributor are connected and sealing properly. It'll affect the running if they are not (you check the timing with the vacuum pipe disconnected from the distributor and blanked off)

it just passed mot with no problems so it cant be out by much.i might get a timing light and adjust the distributor abit see if that helps.could the exhaust manifold leak cause a lumpy idle?