Scirocco GTS Running rich on start up

[Brenjacques]

Hi all,

Finally got my hands on a Scirocco, a 1985 1.8 GTS. It is in good shape but a few bits to do on it to get it perfect. The first thing I need to sort is it running rich on start up.

It is still on the original carb and the engine is totally standard. When turned over it will overfuel and the revs will drop to below 1000rpm and become real lumpy, after half a minute it will smooth out and rise to around 2k RPM, going close to 3k as it is close to being warm. Once it is warm it has no problems and sits at around 1k with no problems so I presume a problem with the choke causing it to run too rich. I switched it off yesterday when it was revving high and got a bit of over run from the engine.

Anyone know where I should start looking?

[james butler]

check all vacuum connections and wired connections as any of these not being connected or leaking can cause problems.
the pierburg is a good carb when it works but its so troublesome when it plays up most people (myself included) change it for a weber.

good luck with it

[GT_II]

Check that the coolant hoses feeding the choke and wax stat heat up as the engine warms up. I had a problem with excessive idle speed on mine during warm-up and traced it to a lump of oxidation inside the choke coolant channel nearly blocking off the coolant flow through the choke and wax stat. I found it easy enough to dismantle and clean out the choke cover channel, after which I took the opportunity to thoroughly flush out the whole coolant system and upgrade to G13 mixed with distilled water.

Not directly relevant, but another thing I learned when trying to set the idle fuel mixture for the engine when warm is that the mixture screw on the 2E2 operates in the opposite way to other carburetors - turn the mixture screw clockwise to enrich the mixture and anticlockwise to weaken it.

[Brenjacques]

Thanks for the tips, I finally got round to taking a look at the carb today after reading up a bit on them. The carb flange had a slight split so I have replaced this. I removed the carb and had a look over it, the waxstat had some crud inside so I presume it is on its way out although testing in warm water did show that it was still working, so for now I have put it back.

I applied vacuum to the pull down unit, removing both pipes and attaching a hose to 'A' , this part was interesting. I'm not too sure if there is a diaphragm inside and if it is damaged. Sometimes the applied vacuum would open the choke but other times it was drawing air from somewhere and failing to operate. By pushing air back through the A hose and again applying vacuum it would operate okay before failing to again. The adjuster also makes very little, if any adjustment to the choke when applying vacuum.

When the car is started, the three-four point unit does nothing until the engine is warm and then draws back in to reduce the revs, I do get a click from the engine bay when the ignition is started so I presume the switch is working okay. Is the three-four point unit doing its job correctly?

After all of this and refitting revs sit just above 2k rpm until warm where they reduce to 1100rpm. I'm sure it is still running rich even then, the exhaust is a bit smokey and smells rich even when warm although it no longer goes up to 3k and I don't have any over run but it still isn't right just yet.

Surprisingly no air filter either so I'm off to get one now. I think this has probably been a problem for a while by the looks of things.

[james butler]

leave the airbox off and look into the carb and see if the choke is actually open all the way, it does sound like that one diaphram has had it.
if it is open all the way i would consider just tweaking the mixture to make it leaner but obvioulsy check every thing else before messing with any of the screws.

[Brenjacques]

The choke is fully open once warm so the autochoke mech looks to be doing its job okay. I'll order a pull down unit and get it replaced. I may aswell throw a new waxstat on too, although this is still working it will save more trouble in the future as it looks original. I'll replace the rubber tubing whilst doing so, the original stuff is still doing it's job but definitely degrading so again worth doing whilst its off.

[Brenjacques]

Hi all,
the saga continues with the 2e2. I've changed the waxstat, the pin didn't protrude nearly as much as the new one when cold so I replaced it. The pull down unit seems to be doing its job but I am still getting erratic revving. I tried adjusting the mixture screw and I think I have found the problem. I have adjusted it a fair bit in both directions but it has no effect at all so I'm thinking that something internal to the carb to do with the mixture screw is faulty. Still the same faults, low revving and smoke due to overfuelling at start up, then it'll rise as the choke opens further where it'll sit at nearly 3k before the 3-4 point unit kicks in and drops the revs down to 1100ish. Is it time to take it out and dismantle it? Or does anyone know of any company that rebuilds them? I'd rather stick with the 2e2 just to keep it original.

[mark1gls]

The Pierburg carb is great when running well but a pain when it goes wrong, you may find it difficult to find a specialist on a that sort of carb. I had running problems with mine and gave up trying to fix it and fitted a Webber Carb as it’s alot simpler to set up and maintain.

There was a thread on here about trouble shooting a Pierburg...

Found it... not sure how much help it is?

viewtopic.php?f=12&t=18845&p=143190&hil ... rb#p143190

I also find this on the Mk1 golf forum, rubjonny knows his stuff..

https://vwgolfmk1.org.uk/forum/index.ph ... air-your_2

[Brenjacques]

Thanks to everyone for all the help on this one. After some more reading and a few enquiries I suspected the carbs TTV wasn't working, the fuse was fine so I checked voltages on the plugs to the carb. The plug to the TTV had no voltage present, pulled the rubber cover back and one wire had pulled from the contact, put it back and it worked first time.

It feels a bit lacking in power and I suppose it could really do with a proper set up although it is more or less there. I'm sure the local carb place will be more inclined to take it now it's working as it should!

[Brenjacques]

Hi,
I'm about all there with the carb now, it seems to be performing more or less as it should. I just want to query a bit of a problem when starting. Cold start is fine, the engine will fire up straight away. If I'm starting when the engine is warm, after a short break of being off it struggles and takes a bit of turning over. Sometimes it is a bit worse than others and just kind of splutters back into life and feels a bit lumpyish for a short time. I'm going to change plugs, leads etc as they look a bit old plus I would imagine the plugs are fouled from it running rich for so long, but I doubt this is going to be a magic cure. Just wondering if this is still carb related? I think so as the idling also seems to vary from 850-1k quite a bit so everything is not quite right just yet but it is good enough to use without much problem now.

[GT_II]

I'm not sure if this helps, but according to the instruction manual:

Carburetor engines (obviously only applicable to the Pierburg 2E2):

Starting a cold engine

The carburetor is fitted with a fully automatic choke.

Before and during the starting process, do not depress the accelerator.

• Start engine.

If the engine does not start at once, stop using the starter after 10 seconds, wait about half a minute and then try again.

Starting from a warm or hot engine

Slowly depress the accelerator pedal while starting and hold it in the full throttle position - do not pump the pedal!

• Release the accelerator pedal immediately the engine starts.

So it seems that even with the most advanced carburetor technology, cars could be reluctant to start in some conditions and required a special technique, even when new.

[Brenjacques]

Ah that's alright then, I'd imagine with the carb not being fully set up it will make things a little worse. A bit off topic now but it saves me opening a new thread, how much pressure should I be getting in the cooling system? Just I was out this evening and noticed the temperature was just above half way when I pulled up. I left it to run for a few mins and it continued to rise but I didn't leave it for too long. Feeling the pipes they were quite hot and had quite a bit of pressure in them, quite hard when being depressed. I know it is normal for some cars, but is it normal for these? I have been questioning whether there may be a HG problem but there's equally no air bubbles/froth in the expansion tank and I'm not losing any fluid or getting white smoke, oil is fine too. The starting when warm problem and the pressure in the cooling system is giving me some suspicion though.