Model specific boards => Golf mk2 => Golf mk2 how to guides + info => Topic started by: rubjonny on 19 March 2005, 10:12

Title: Pierburg 2e2 carb FAQ
Post by: rubjonny on 19 March 2005, 10:12
Here is a list of Pierburg components and troubleshooting tips:

TTV & idle over run valve:
These should both get 12v when the ignition is on, and there should be an audiable 'click' from the engine bay when the key is turned.

3/4 Point Unit:
When engine is off, should be extended to 14.5mm. When engine is started should retract to about 8.5mm after a varying delay, depending on temperature.

Pull Down Unit:
When engine is running, you should be able to close the choke flab by hand easily until the last 5mm or travel, then resistance should be felt. If not the pulldown unit is defective or incorrectly adjusted (it has a small screw on the end of the plastic lever, but this should not need to be adjusted)

Inlet manifold preheater:
Located at the bottom of the inlet manifold, looks like a hedgehog. The electrical connection is at the back of the engine bay behind the carb, should get 12v when engine is cold, should switch off when engine has warmed up. (controlled by grey temperature sender, see below)

Vacumm Unit Stage 2:
This opens the second throttle butterfly when you have your foot down, not had a problem with this myself but I imagine sympoms for a failed unit would be no power under full throttle.

Waxstat, also known as 'Expansion Element':
Helps control the idle untill the autochoke switches off completely. Is full of wax which is heated by coolant. As the wax expands a pin exends from the unit pressing a lever which brings the idle down. Check by throwing into a bowl of hot water, the pin should extend. This has been known to fix dodgy units as it 'resets' the wax apparently!

Should get 12v with the ignition on & engine is cold, should switch off when the engine is up to temp. (controlled by the red sender, see below)
The autochoke should pass current, test by placing one prong of a multimeter on the plug, and the other on the autochoke housing.
You can check the autochoke heater visually by removing it and checking the heater spring around the outside of the unit, looks like the kind of spring you find in a ball point pen. When refitting, align the mark on the housing with the notch on the choke.

Temperature Senders:
At the front of the engine block there are 2 temperature senders, red & grey. The red sender controlls the autochoke, the grey controls the inlet manifold preheater. When the engine is cold these should pass current, when the engine has warmed up they should stop passing current. You can test units from the scrap yard by putting them in a tray filled with boiling water (just immerse the metal bit at the bottom!) to make sure they switch off correctly.


Last but by no means least, the inlet manifold coolant channel o'ring, the o'ring degrades over time eventually blocking the coolant channel completely. Often overlooked this is key to having a 2e2 carb that actually works! If this coolant channel is blocked expect poor running when cold, smoking, petrol smells, engine overruns and having the engine rev up to 1.5k+ at random until the engine is VERY hot.
Start the engine from cold and feel the autochoke unit, it should get hot quickly. This is becasue it needs a good flow of coolant from the back of the head to work properly, when the car has been running for a few minutes it should be boiling hot to the touch.

Before you start, MAKE SURE you can reach ALL 6 bolts on the inlet, the third one from the right is wedged between the inlet and exhaust manifolds and is tricky to get to. You'll need a new gasket and the o'ring, part 32 in the diagram below.

026 129 717 D - Gasket - 5.32+VAT
035 121 171 C - o'ring - 2.70+VAT

First take the carb off:
Remove the airbox
Remove the fuel line from the carb
unplug the 2 electrical bits on the left side at the back
remove the earth connection from the front
Unplug the vacuum connection to the green reservoir
Remove the coolant connection to the inlet manifold
Remove 3 securing bolts
Check the condition of all the vacuum pipes, do one at a time its a bit complex back there

That should give you enough slack to move the carb over to the right out the way, next get the manifold off:
Undo all 6 bolts, remove manifold.

Then lever out the knackered old oring and clean up the hole it came out of. While you're here check the inlet manifold preheater. Then fit the new gasket & oring, refitting is the reverse of removal?

Edit: Whilst you're there you might want to replace the core plugs that are only accessible when manifold is off. (thanks for the tip pmhpmh!)

Title: Re: Pierburg 2e2 carb FAQ <- Mods please sticky
Post by: rubjonny on 19 March 2005, 10:14
Tips from Drew21
the channel heater unit should get a permanent 12v and is earthed through the carb, if not working check the volts at the connector and check the carb earth strap

3/4 point unit, when you turn the engine off the piston should fully withdraw and the extend to its starting position. Failiure to do this indiates a fault with the overrun solenoid.

pull down unit
to check for vac leaks in this unit attach a pipe to the lower port and unplug the upper port. Suck on the pipe. The arm should move a small amount and then stop when the vac collapes. Then if you put your finger over the upper port ad keep sucking the arm should withdraw a bit more and hold vacuum. If it fails to hold vac then replace.

hot air flap, this can seize during the summer as it doesn't get much use. So as the weather gets colder its worth spraying ome WD40 on this and making sure it moves

poor running can be caused by air leaks around the base flange, can be a cheap fix if you're having problems with missing at idle. To locate vac leaks try spraying gamping gaz (carefully) around the vac pipes and the base of the carb. Changes in idling should be heard when you find the leak!!

Tips from Mark25
some stuff about the part throttle channel heater:

With the ignition off and the heater supply wire dissconnected, the resistance of the heater is about 3.8 ohms measured back to the negative of the battery. So this value includes all the wiring and earth straps back through the carb and engine.

With the ignition on and the heater supply wire connected, I have 11.3 at the heater supply wire. Therefore I am loosing about 0.5v across the switch or relay that controls the heater.

I think the symptoms if it?s not working are; the car runs rough until the engine is totally warm. You can get round this with a manual choke by just leaving it out longer. With mine I can put the choke in as soon as I?m out the drive way, in all but the coldest, ie -5oC, weather.


EDIT: the above tests were done on a unit that had been transfered to a weber.

Tips from EZ_Pete on pulldown unit replacement
I shall abbreviate pulldown unit to PDU for convenience :)

I'm going to assume that you have tested the old unit in accordance with Drew21's method detailed above, and it has failed.  You should also check carefully all the vac hoses going to the PDU and replace if they look anything but recent.  The one that goes down to the bottom of the carb from the "A" port on the PDU may degrade/perish due to proximity to manifold warmth.

Tools required: (

In order to show the process clearly, I've photographed a stripped-down carb, and you'll notice that the PDU is incomplete too...but not in any relevant sense.
I managed to change one of these without stripping any parts from the carb, but it is a bit tricky, as the autochoke assy is rather in the way. 

Judicious juggling and bending can remove the old (easy 'cos it doesn't matter if it breaks) and insert the new; you run the risk of snapping plastic parts, however.  You may prefer to make a note of approx. how far the adjustment screw protrudes into the 'slot' and then remove it to make insertion easier.  Access to replace this screw isn't that nice however, as it's from the rear of the carb, and there are parts in the way, as always.  I think it is the safer option probably.

Of course removing the autochoke assembly makes the job easy, but you may not need to if you are brave (the bendy method), or nimble-fingered (screw out method).

View of PDU in-situ. The red arrow shows the direction it moves when the diaphragm is 'pulled' by vacuum. The green arrow points at the part that actually touches the choke flap linkage. The blue arrow shows the stop that limits its overall movement:

The pin securing it: (

Knocking it out/down: (

The adjustment screw: (

Access to adj screw: (

Once you've got the new PDU in and secured with the pin (I think you even get a little 'grippy washer' that fits over the stop too), you will want to set it up for your carb. Don't attach the vac hoses yet, you can set it up without even starting the engine.  You just need one longer hose attached to the lower port "A", that you can suck on.

There are two adjustments, the black circular part at the front adjusts the first stage , the little Allen screw mentioned above sets the second stage.  Look up the settings required for your engine code, my manual transmission EZ requires 2.8mm and 5.6mm for the two stages.  Find some drill bits or similar of the right diameter, measurement is down the front edge of the choke flap, between it and the edge of the barrel.

With a completely cold engine, so that the choke spring holds the flap shut, suck on port "A" with port "B" open to atmosphere.  You should see the flap open about the right amount, adjustable by screwing in, or out, the round plastic bit.  Once you're happy with that, you can set the second stage by continuing to suck on "A" but now with "B" blocked with a little finger.  You will find that the choke flap opens more now.  If this second stage needs adjustment it's that little Allen screw round the back.  You may struggle to do this while sucking and blocking things, so cheat!  Just manually pull the long plastic part of the PDU forwards, as far as it will go.  If that's too far you need to screw the Allen screw further in, and vice-versa. 

Now you can plumb it all in with the correct vac hoses, and away you go.

See below for a table of the settings for all the various engine codes

Please reply if you've done this by an easier method.

Car / years / engine code(s) / transmission
Pulldown gap, first stage (a), mm
Pulldown gap, second stage (a1), mm

Audi 80 1.6CL / '83-'86 / DT / manual
Audi 80 1.6CL / '83-'86 / DT / automatic
Audi 80 GL & Coupe 1.8 / '83-'86 / DS/NE / manual
Audi 80 GL & Coupe 1.8 / '83-'86 / DS/NE / automatic
Audi 100 & Avant 1.8/ '83-'87/ DS / -
Golf/Jetta/Scirocco 1.6 / '83-'92 / EW/EZ / manual
Golf/Jetta 1.6 / '83-'92 / EW/EZ / automatic
Scirocco 1.6 / '83-'92 / EW / automatic
Caddy 1.6 / '83-'92 /  EW / -
Golf/Jetta 1.6 Cat. / '86-'92 / RF / manual
Golf/Jetta 1.6 Cat. / '86-'92 / RF / automatic
Golf Cabrio/Scirocco 1.8 / '83-'92 / EXZ / manual
Golf/Jetta/Synchro 1.8 / '84-'92 / GU / manual
Golf/Jetta/Synchro 1.8 / '84-'92 / GU / automatic
Scirocco 1.8 / '86-'92 / EXZ / automatic
Golf/Jetta 1.8 Cat. / '86-'92 / RH / manual
Golf/Jetta 1.8 Cat. / '86-'92 / RH / automatic
Passat 1.6 / '83-'88 / DT / manual
Passat 1.6 / '83-'88 / DT / automatic
Passat 1.8 / '83-'88 / DS / manual
Passat 1.8 / '83-'88 / DS / automatic

In every case a rather tight tolerance is suggested of +/-0.2mm for the "a" dimension and +/-0.15mm for "a1"  Can't really believe it's that critical myself  :tongue:
Title: Re: Pierburg 2e2 carb FAQ
Post by: free on 22 March 2005, 23:11
vary good read that,  :wink:

shame im soon bolting a webber on mine :cool:
Title: Re: Pierburg 2e2 carb FAQ
Post by: richandhazel on 26 March 2005, 20:59
Yeah some really good stuff there. Nice one :wink:
Title: Re: Pierburg 2e2 carb FAQ
Post by: Bronze MK1 Cab on 17 June 2005, 13:40
Good info there, I ended up chucking my Pierberg carb and put a weber on.
Title: Re: Pierburg 2e2 carb FAQ
Post by: Si on 13 January 2006, 16:19
How do you get Inlet manifold off?
I can only get to two of the end bolts (alen key bolts)
Are the others underneath? if so do i need to remove exhaust manifold?
Title: Re: Pierburg 2e2 carb FAQ
Post by: rubjonny on 18 January 2006, 08:25
You need a long thin extension bit to get the others off, its tricky but once you've done it you'll never forget how  :grin:

And here are some vacuum diagrams while I'm here:

Rear of carb, the tube in the red circle is where the vacuum pipe to the airbox connects:

Front of carb, the tube in the red circle is where the pipe that splits off from the vacuum reservoir green pipe connects:

Vacuum overview:
Title: Re: Pierburg 2e2 carb FAQ
Post by: PETEL on 26 November 2006, 16:10
Its easier if you use a mirror to locate the recessed inlet manifold 6mm allen bolts.

Also on my 1990 1.6 driver the red thermotime switch, black/lilac wire, controls the inlet manifold pre heater (hedgehog) and the grey thermotime switch, black/yellow wire, controls the autochoke.
Title: Re: Pierburg 2e2 carb FAQ
Post by: RIPP3Y on 04 December 2006, 23:01
very intresting read, if only i had the time and balls to sort my carb out (over running, petrol smell and high revving all present).
 Time for trip to the garage.
Title: Re: Pierburg 2e2 carb FAQ
Post by: rubjonny on 05 December 2006, 10:09
Tell them to replace the o'ring in the inlet manifold, I bet its degraded and blocked the flow of coolant :)
See this link for more piccies:
If you're near Bracknell I could do it ;)
Title: Re: Pierburg 2e2 carb FAQ
Post by: RIPP3Y on 05 December 2006, 18:37
Mate, if i wasnt so far from you, i`d be there as fast as my dodgy carb would let me :grin:.
Anyhow, with this info at hand i can visit the garage with confidence, so cheers. :wink:

Title: Re: Pierburg 2e2 carb FAQ
Post by: jamie_f on 09 April 2008, 14:02
hay im a complete novice when it comes to working on carbs, at the moment im having trouble with the auto choke basicly it doesnt work at all, i tryed bridging the choke thermo switch and seeing if that would start the auto choke off but no joy, im getting a current coming threw the thermo switch up to the carb but after this im not sure where to check, any help would be much appreciated
Title: Re: Pierburg 2e2 carb FAQ
Post by: rubjonny on 09 April 2008, 14:23
the heater doesnt do a great deal compared to good coolant flow through the carb, the choke housing should get hot very quickly, if not the o-ring is blocked!
Title: Re: Pierburg 2e2 carb FAQ
Post by: nictron on 27 November 2008, 13:47
hi, im having what i think is a slight problem..could just be me being picky :tongue: but anyway here we go... basically i was having some trouble with high revs, petrol small etc, all the usual stuff. turned out to be blocked o-ring, so i replaced that, everything was a little better, but still reved quite high or really unevenly. i then noticed that the choke wasnt actually operating properly as it did not have any resistance when i pushed on the flap. tested the choke unit itself, everything seemed to be working  :huh: sucked as hard as i could on the pull down unit...nothing happened. luckily i had a spare 2e2 in teh garage so tested the pull down on that and it worked so i swapped them over. easy. the problem seemed to get better, thought everything was solved. i had also bought myself that haynes carb manual, very handy. so i decided to go through the overhaul and adjustment procedures to get everything back to the proper settings. did the idle cam positioning and all that stuff (using a nicely bodged setting tool made from a piece of wood and a screw :P ). after doing all that i started playing with the idle control valve and CO screw, finding it very hard to get a good combination of the 2. the one i did find it ran nicect was if the control valve was screwed fully in meaning that the pushrod was as far out as it would go (didnt think that it could be right to be fully adjusted either way) but even with it fully adjusted the revs now seem maybe too low? and the throttle plate adjusting screw doesnt actually touch the pushrod :huh: and after all that... there seems to be a large flat spot on acceleration, meaning i can floor it, revs seem to hesitate and are a bit jumpy and then slowly build up till i can feel the kind of power band starting to pull me along. i dont know wether or not this is just normal and i should be a little gentler on the throttle  :grin: or there is some unlying problem i cant seem to work out. im only 18 and lack of experience it making it difficult to tell :P

bit of an essay haha,
any help would be much appriciated.

also if anyone has got a weber 32/34 theyd like to get rid of cheap il be happy to take it :)
Title: Re: Pierburg 2e2 carb FAQ
Post by: rubjonny on 27 November 2008, 13:56
you can bend the metal flap and/or adjust the threaded screw on the lever that hits the 3/4 unit, to give you the correct idle when everythign else is sorted.  Set the idle valve so the 3/4 point unit is extended to the specified length, then use the lever to fine tune the adjustment.

also worth looking at the waxstat pin lengths, make sure that is pushing off as specified, plus the pulldown unit has some adjustment too if required :)
Title: Re: Pierburg 2e2 carb FAQ
Post by: nictron on 27 November 2008, 14:44
ah ok, wasnt sure if i could jsut start bending bits to fit lol. so the throttle plate flap's pin is supposed to be touching the pushrod at all times?? waxstat should be ok bought a new one about 6months ago.
Title: Re: Pierburg 2e2 carb FAQ
Post by: rubjonny on 27 November 2008, 15:09
mr haynes has this to say in the mk2 manual:
Start the engine and let it idle. The diaphragm pushrod must now be extended approximately 8.5 mm (three-point unit), or 9.5 mm (four-point unit), and must just contact the fast idle adjustment screw.

and this in the carby manual:
If the engine is at operating temperature there must also be a gap between the throttle stop screw and the pushrod.

Unfortunatly I dont actually have a carby any more, or even any spares to look at!  I'd guess the lever has been played with in the past if after resetting all the clearnaces as per the carby manual theres a big gap between that lever and the 3/4 pushrod!
Title: Re: Pierburg 2e2 carb FAQ
Post by: nictron on 27 November 2008, 15:18
hmm... ok. well come to think of it its wasnt a massive gap only 1-2 mm. but the strange thing is that the idle seems a little low, sounds as though its going to conk out if i leave it, even when the pushrod is fully adjusted outward, i guess its jsut trial and error and see what happens.

cheers for you help anyway :)

tempted to just get a weber and be done with it tbh lol
Title: Re: Pierburg 2e2 carb FAQ
Post by: Neo Badness on 01 December 2008, 17:02
Excellent sticky, loads of useful info, however i strongly reccomend splashing the cash for a manual choke weber item. Changed one on my 1.6 driver(RIP :cry:) and was like a new car, better everything, only did about a 100 miles before got taken off road but good induction noise too  :smiley:
Actually, if someone wants mine it's sitting in a box with all the linkages/bolts/washers etc after stripped the car.
Make me an offer and it's yours :wink:

Title: Re: Pierburg 2e2 carb FAQ
Post by: deanpompey on 14 August 2009, 20:51
some help needed guys, have a 2e2 on a mk1 clipper i just bought, engine fires up and runs, however is lumpy as hell. wont rev above about 2.5/3k rpm sounds,feels and smells like its overfuelling badly, i dont have any idea what im doing with a pierburg, so if anyone can help me with a bit of guidance as to how to adjust the mixture?? idle screw seems to do absolutely sod all!

anyone got a pic of a 2e2 and can point me in the direction of which screw adjusts the co?

Title: Re: Pierburg 2e2 carb FAQ
Post by: rubjonny on 17 August 2009, 09:51
there is a picture on the 1st page, the co adjusting screw is clearly labled :)

however I dont think its a mixture issue if it wont rev, id say you have a problem with the timing or a bad missfire. maybe something more serious wrong with the carb that a badly adjusted mixture screw. if you take the airbox off check the flap on the top is free to move, it should be closed when cold then gradually open as the car warms up.  Also check all the vac hoses carefully, especially the one round the back to the stage 2 vacuum unit
Title: Re: Pierburg 2e2 carb FAQ
Post by: Marc C on 17 August 2016, 08:39

Thank you very much for your postings on this issue.

My wife has a 1990 Golf Clipper mark 1 which has been off the road for a year.  Prior to that, it only did 200 miles a year !! but it worked perfectly.  Only 59,000 miles since new.

After an unexpected 12 month shut down, it started idling at 1,800 RPM.  At first I thought it was the expansion element but, after reading your post on the front page, I felt the auto choke - stone cold even after 20 minutes idling (at 1,800 RPM).

Looks like the coolant channel is blocked.  Repairing it is way beyond me so a visit to a trustworthy garage (we live in Cyprus so finding one who is familiar with Peirburgs is not so easy.)