i need some old school help!

[FD3SNuttah]

have been having a \'mare with my 1986 1.3 carby $hitter VW Polo recently. The car was fine till a week ago where it suddenly decided to spit its dummy out.

I was in traffic and noticed that the temp was creeping up a little bit more than it usually does. I got the car home (the temp guage was pointing at 3/4) and anyway found that the thermostat had stuck closed. i changed that part and now it doesnt over heat. (you would think this is an easy job - but it isnt as it wont stop it leaking - however i sussed out how to fix the leaks)

but since this happened it refuses to idle!!

first it was pretty lumpy but now its got to the point where I\'m constantly left foot braking when i come to junctions(LOL). It doesnt cut out when the auto chokes on - it runs as per normal. till it warms up then it start dying on me when i stop.

So naturally off i go to my local GSF and i get some parts

new plugs and the dizzy cap and the rotor arm,
gave the engine new oil and filters
and gave the little bugger a wash.
stuck some injecter cleaner in the tank
sprayed some hammer drill oil/cleaner into the carb
checked vacuum hoses they seem fine but im thinking of changing these next anyway.

non of this has fixed my problem with the idle. but now when I\'m driving along the car feels very responsive and its more refined and feels like its going a bit quicker than it did before! its not drinking anymore fuel than it used to.

earlier today i took it on the motorway for a good run and drove it up to 85mph and i heard a big pop out of the exhaust! i bet it must have spat a flame!!  :King

i was advised by a mate to adjust the ignition advance by a few degrees which didnt change a thing as he thinks its running too rich. however when i push the little flap on top of the carb choke down - it seems to idle fine until you let go

so what have i got here? am i too rich or am i too lean at idle? air leak? someone please help me for god sakes and make the madness stop! ive tried asking on the club polo site and theres been NO response!! LOL

i have had a search on there and all i can find is people changing carbs for DMTL\'s which i dont wanna buy new - cant find one second hand!

[RobbieRX-7]

Could be a couple of things. Airflow meter, automatic choke unit. I would put my money on either of those

[grinder]

have you checked the advance/retard pipe ( i know my mini had exactly the same problems ) and this fixed it

does it have a manual choke - is it working OK ?

if you can push the flap on the carb and it runs well - then this would be my starting point

can you not adjust the idle slightly and raise it

[FD3SNuttah]

hmm when its cold it idles fine at 1.5 to about 2k  i think that when it is warm the auto choke is disabled? besides if it was on all the time the car would drink loads of fuel...

grinder i twisted the dizzy (advanced and i retarded it) but it didnt do anything, so i put it back to where it was. and no it doesnt have a manual choke

it doesnt have an air flow meter or an ECU!! which is what makes this all confusing.

im going to try and adjust the idle mixture screw. this might be cheating a bit but if it works then ill be happy.

[RobbieRX-7]

You said yu put injector cleaner in the tank

[FD3SNuttah]

yeah cos the shop didnt have any carb petrol treatment. i thought it would be the same stuff?! to be on the safe side i stuck a more concentrated mix into the tank - its supposed to be 50 litres to one bottle but i put 35 litres to one bottle!

i have managed to find a blow apart diagram of the carb - i was struggling with what is what bit - essentially i think if i approach the problem as if its just like a mechanical ECU i cangt go wrong.

ive made the assumption that its running too rich on idle. as when i close the butterfly on top of the carb its restricting the amount of air going in. perhaps adjusting the idle mixture will enable it to knock down the amount of fuel going in.

perhaps it could even be that pressing the flap down increases amount of fuel?

im gonna get home from work and then try the idle mixture screw

[FD3SNuttah]

Stu, i did try adjusting the idle screw but the problem with that is i worked out that the screw would need to be about three times longer than it is to push the cam back enough.

[FD3SNuttah]

aye i fixed this problem.

turns out that a vac hose going into the carb had a split. The car runs fantastic now, it idles so good you cant even hear it running!

[mpk490p]

simple old skool a 10p pipe!