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I have a Scirocco 90' GT2 MK2 1.8 Carb. A few weeks back the car was stuttering, revs going from low to high then at idle it would go to 100-200rpm max and cut out. This car has a brand new tank and fuel lines on it. I changed the inline fuel filter and got some carb spray and cleaned the carb which was tbf a bit grim. The car stopped stuttering and all was fine.
Until today
Stuttering with low rpm but only after acceleration. I can turn the car on and it'll idle at 1000rpm no bother. Soon as I rev it up and let it go back to idle, its back to 100rpm, shaking and stuttering, then it cuts out. So again, I changed the inline fuel filter (the other one is practically brand new) and sprayed some carb cleaner in the carb which fixed it for about 10 mins to get me home then it's back to stuttering.
Carburettor on its last legs or needs stripping down totally and cleaning? It's a Pierburg.....
Check the rubber flange beneath the carb and the inlet manifold isn't split. Start the car and gently tilt the carb from side to side and see if you can hear it drawing air or worse hanging off.
Flange is perfect, no problem there. The car can run, drive and idle fine for an hour or even a week then all of a sudden its erratic for a while, then again back to normal. It's all very random, that's what's more annoying. Mind of its own....
I hope to write more soon
vw made a good engine a pierburg made a good carb to go with it
then the customer care dept said fine now we want your gran to be able to start it on the wild out back of scandenavia at say minus 25
all without the aid of a manual choke....there in a nutshell was the downfall of many a good carbed mk2....the rich mixture is dealt with by the autochoke...if your coolant is pumping through the manifold ok this is usually ok but all the rest of the crap they use to keep the idle high for warm up is asking for trouble.....I have ripped it all off and tickle the throttle my self...need advice from someone who understands thread pitch as the idle screw needs to be longer (very fine pitch)....will get back to you again....and p.s to all MAFCO MCC28....buy it if you can cheaper than a weber
carbs fascinate me.....so the pierburg is fine on its own we just all need to get together an revamp it so we can all deal with it
second stage....fine....(open the throttle to let it clear the stop...suck on the pipe from it and make sure it moves the main flap but this is usually ok
autochoke....ok the choke flap that restricts the air thereby enriching the mixture is CLOSED by DEFAULT....unless you want you vehicle to die a slow (but painless)death of sooting (is that a real word)up that many do...you must provide it with hot water and 12v....water must travel (NOTE )from the manifold to the autochoke housing....this is notorious for getting blocked...I know because I am half way through the job....ANYONE NEED HELP ON THE OLD MANIFOLD REMOVAL LET ME KNOW..OK but before the water gets hot enough to begin to open the choke flap, 12v is sent to it via the grey sender from the front of the engine where the coolant junction pipe is....this helps to open the flap when only when the coolant is cold.
THIS FLAP MUST OPEN...YOU MUST HAVE GOOD FLOW AND 12V TO THE UNIT WHEN COLD.
in the old days you pulled out the choke but not for long...no flooding....anyway we have another unit that connects to the green ball and carb etc via vacuum pipes...looks just like the second stage unit at the back except this one is at the front looking at the carb.....its call the pull down unit
ALL THIS DOES IS OPEN THE FLAP ENOUGH TO STOP A COMPLETE FLOODING NO AIR IN THE MIXTURE SCENARIO....
in my humble opinion we can ESPECIALLY IN OUR CLIMATE AND WITH OUR KNOWLEDGE...SIPLIFY THIS....ok trust me... leave the tube that goes to the carb...cut the other and block it....chuck away the green ball and the SMALL no return valve and block the pipe as it joins the brake servo vacuum system......EVEN NOW YOUR REVS MIGHT BE HAPPIER
OK ALL THE REST OF THE CRAP FITTED ON THE BACK OF THIS CARB CAN GO
the part throttle heater I want peoples experience with...one of my GTs seems fine without it...not sure yet till the winter etc more tests etc..
the rest of the rubbish is all designed to keep the revs up when cold....some thing I now just do with my foot !!!
that means the three four unit, the temp time unit, the overrun (external style i have not dealt with the internal style one YET) valve and the expansion element can all take a running jump
while we are ripping stuff off.....the air intake can be sliced off above the hot exhaust intake and 63mmID neoprene intake tube can replace it in the summer or just leave it off in the winter or up north......
the vacuum tube from the airfilter box can again be blocked where it joins the carb....same around the back what removing all the rubbish
NOW THE DIFFICULT BIT WHERE WE ALL NEED TO WORK TOGETHER.....IDLE ADJUSTMENT
I AM BEGINNING TO THINK MAYBE LEAVE THE 3/4 POINT UNIT ON UNCONNECTED AND USE an ADJUSTMENT SCREW THERE INSTEAD OF THE ONE TUCKED AWAY BEHIND THE SECOND STAGE UNIT
EITHER WAY BOTH SCREWS ARE TOO SHORT AND BOTH ARE A VERY FINE ODD THREAD....MAFCO PROVIDED A LONGER ONE IN THE KIT SO I HAVE USED THAT FOR NOW....I will get back to this but HELP any engineers out there with thread pitch etc
THATS ENOUGH FOR NOW AND REMEMBER THE MK2 WITH A PIERBURG IS JUST FINE WE JUST HAVE TO STANDARDISE THESE MODS FOR EVERYONE TO GET THERE HEADS AROUND AND NOT GO WEBBER CRAZY
ciao mikey
Cheers Mikey for all the information. The car has more or less died. If I touch the accelerater it stalls. If I put the accelerator to the floor it revs, then loses revs, up down up down until it conks out. Today after turning the engine off it has continued to run on until I put it into gear and let the clutch off to kill it.
I'm at a loss. I would have been quicker putting a diesel straight in, could have had that done in a day. Rage!!!
I've ordered a new distributer cap, rotary arm and spark plugs to rule out that, but if that doesn't fix it I'm stumped.
Bin the Pierburg and fit a Webber, the Webber is a much simpler carb to set up and maintain.
I tried several times to fix mine then gave up and fitted a Webber, 15 years later I've still not had any trouble with it.
bare with me later I will give you a step by step with photos.....trust me man there is nothing the wrong with the pierburg after we bin half the gubbins bolted to it....I intend to change the whole view of this carb here and on any golf site.....since I was a kid I loved carbs....they don't phase me and I ASSURE YOU that we WILL solve ANY induction problem you or anyone else has......just finished putting one of mine back on but if I have to remove it again to give you even more detailed photos it is not a problem......laterz Nathan
The Pierburg carb is a good carb and in so many ways better than a Webber, it's just the Pierburg is a complex bit of gear and it's hard to find someone who knows about them and can tune them.
Mikeyboy seems to know what to do with them which will be very helpful to fault finding, I needed to fix my car ASAP as it was my only car at the time and I was feed up with an 1 hour and 3 buses journey to work so that's why I changed mine over.
ok
first read Zen and the art of motorcycle maintenance....it will change the way you deal with your car and a few other things !
meanwhile......please read the reply I have written in the "fuelling issue thread" its very relevant.
either way lets take it slow.....I need you to have or have access to a multi- meter....they are cheap...I NEED YOU TO BE SURE OF 12V TO THE AUTO CHOKE UNIT....LET ME KNOW WHEN YOU ARE ARMED....IF YOU CAN IT WOULD BE VERY USEFUL IF YOU MAKE UP OR FIND ABOUT 2 FOOT OF WIRE WITH A SPADE TERMINAL ON........THAT SHOULD BE ALL WE NEED
NOW I DIGRESS....NATHAN BEFORE WE GO ON....TELL ME IS THE EARTH WIRE IN GOOD CONDITION BETWEEN THE CARB AND THE ROCKER COVER (CLEAN TERMINAL CONNECTOR AT THE ROCKER END) ???
AND BETWEEN THE BULKHEAD (COIL MOUNTING) AND ROCKER COVER ??? IF THERE IS NO PROBLEM THERE I ALSO HAVE A GUT FEELING YOU MAY HAVE SHIT IN YOUR FLOAT CHAMBER.....THIS CARB IS EASY TO WORK ON TRUST ME....JUST BE SURE YOU HAVE THE CORRECT SIZE OF CROSSHEAD....SOME SCREWS CAN BE TIGHT.....ANYWAZ ONWARDS A LITTLE...PROBLEM OR NO PROBLEM THE FOLLOWING CHECKS should BE MADE
1/ TAKE THE PLUG OFF THE GREY SENDER ...CAN YOU SEE IT.?? ITS A BIT OF A FIDDLE.. WHEN THE ENGINE IS COLD THIS SHOULD PASS CURRENT....THAT MEANS WITH YOUR METER ON CONTINUITY TESTER OR RESISTANCE SETTING IT WILL GO BEEP WHEN YOU TOUCH THE TERMINALS IN THE GREY SENDER....NOT WHEN IT IS HOT
2/TAKE OFF THE AIRBOX......SPLIT THE CONNECTOR ON THE WIRE TO THE AUTO CHOKE...SEE IT?? WITH YOU HOME MADE LEAD PLUG THAT TO THE AUTO CHOKE INSTEAD . CLIP THE BARE END TO THE POSITIVE +++++ TERMINAL WITH CROCODILE (JUMP LEADS)....SIP YOU TEA...CHILL AND WITHIN 5 MIN OR SO THE FLAP must must START TO OPEN
3/REMOVE THE CLIP IF YOUR MOTOR HAS NOT BEEN WORKED ON OR JUBILEE AND PULL OFF THE PIPE (THAT LEADS FROM THE MANIFOLD TO THE AUTO CHOKE UNIT) FROM THE MANIFOLD.....WITH CAP OFF YOUR COOLANT EXPASION TANK.....WATER MUST FLOW FROM HERE NOT DRIP OR BE DRY
THE CLIPS ARE SHITS...ALWAYS USE A JUBILEE WHEN YOU RE CONNECT THE PIPE
ANY QUESTIONS LET ME KNOW....GONNA TRY AND UPLOAD SOME PICS NOW
gonna learn to make pdfs
then get the mafco instruction to you ALL
you can see official paperwork telling you to BIN half the pierburg the bad half
anyway I like the idea of keeping the auto choke...when it works its fine its cool
see you soon
Today after turning the engine off it has continued to run on until I put it into gear and let the clutch off to kill it.
That's a separate problem unrelated to the carb - if a petrol engine runs on after you've killed the ignition then something in the combustion chamber is retaining enough heat to ignite the mixture, usually carbon build-up on the spark splugs.
