Possible fuel starvation issues with the GTS

[Brenjacques]

Yep, I was happy as anything getting back behind the wheel and taking it for a spin. Don't know what it is but there's so much fun to be had driving these around. I'll have to bear 1st gear in mind if it's parked up for some time in the future. To be fair the shoes don't stick badly but there's a slight resistance and then a clunk as they free away.

Much more to be done now to keep it in good order, it's beginning to fill a list faster than I can tick things off but it's mostly just simple and remedial stuff. Most annoying is the clutch which I had sorted a few months back and now feels just like it did before I had it done and I really do need to treat it to some new seals especially in the boot after what I found yesterday.

[RussGLAuto]

Great news!

Sounds like your doing all the right things... I gave GLAdis to a classic car restorer to change the fuel tank, hoses and hard fuel lines also as I didn't have a full car lift at the time. They did it in a day.

[Brenjacques]

Yep, I'd rather pay someone with better equipment to do it than to go through the struggle of putting it on stands and working with little clearance. Annoyingly I've found that I'm still having trouble with the carb pump jet dripping when the engine is shut off. Nothing of fault could be found with it and I don't think it has anything to do with flooding from the float bowl as it only happens after switch off and no fuel leakage from the main jets. I've got in touch with Webcon and FRC (they supplied it) to see what can be done or if there's any mods (I know other models have this same problem) as really it's looking more like a manufacturing issue now and it's been doing it since new.

Plan B would be to dig out the Pierburg that came off it, give it a strip down and service and see how that goes instead. I remember it would run okay but the autochoke wasn't the best no matter how I adjusted it, not too bad in summer but it wasn't desirable at this time of year.

[RussGLAuto]

I went with Plan B. Never looked back!

[Brenjacques]

I dug the Pierburg out of the shed last night, it doesn't look too bad for itself considering it's been sat in there for three years, mind I did keep it well wrapped.

To be honest it did work fairly well but from memory the autochoke wasn't good, it would either come off too early or there'd be too much choke, I could never find a sweet spot in the adjustment where it would open the choke at the correct sort of timing but that's probably due to an incorrect fuel mixture or aging of the coiled spring. I'm happy to clean it up and try again though but it's going to take some time as it's a real oily mess at the minute. Obviously the airbox had the oil problem for many years as it's completely caked in it.

The only real problem I had once was one wire of the TTV 12v supply which had came away from the contact in the plug causing it to randomly rev at 2krpm and run on if switched off during this.

For now I can still use the weber, it works fine when running but it's when shut off that it decides to start playing up. I just don't like the idea of fresh petrol dripping onto a hot manifold.

[GT_II]

During the first couple of years of my Scirocco ownership, I experienced issues with warm-up on my Pierburg. I'll share these here, in case you decide to resurrect the Pierburg, or to help anyone who experiences similar issues. However, before tampering with any carb settings, I would recommend downloading a copy of the Pierburg 2E2 service manual, readily available online, and following the step by step instructions for testing and setting up, for example to make sure the vacuum operated devices are working correctly and to check the throttle basic setting in case it has been tampered with in the past.

The first issue was really slow passage of coolant through the wax stat and choke housing - easy to check by feeling the temperature of the coolant hoses feeding the carb as the engine warms up. This started to cause the engine to rev high during and beyond warm-up. Initially I feared this would be down to a blockage in the coolant channel of the inlet manifold, something which is documented online, but it turned out to be caused just by some corrosion within the coolant channel of the choke housing. After clearing that out, both the wax stat and choke housing started to warm up quickly with the rest of the engine.

Soon after, the newer style plastic wax stat on my carb sprang a leak, so I had to replace it. This turned out to be a blessing in disguise, as it became apparent after installing the new one that the old wax stat had become seized. However, with the new wax stat installed, this created a new problem, as the idle speed then became too low during warm-up, causing the engine to stall.

After reading the Solex and Pierburg carb manual from Haynes, which provides a detailed description of how the 2E2 carb works, I went through the step-by-step process for setting up and testing the carb set out in the Pierburg 2E2 service manual. Several steps into the process, I found at some point in the past someone had tampered with the setting of the warm-up cam, presumably to try to compensate for the faulty wax stat. After setting the warm-up cam correctly, the behaviour of the car during warm up has been flawless.

The last issue, I discovered when checking the setting of the choke spring. No doubt to save cost, Pierburg at some point updated the choke mounting bracket from aluminium to plastic. To maintain electrical continuity, they inserted a flimsy metal ring around the choke body with a small tab to bridge the gap to the carb body.

At some point, this tab had been broken, resulting in loss of electrical continuity, preventing the electrical heating coil in the choke housing from passing current. This meant that the choke had become reliant on coolant heating alone, resulting in a richer mixture than required during warm-up. To restore electrical continuity I have inserted a small earth wire to bridge the gap. This should hopefully improve economy and emissions during warm up:

Choke earth wire.jpg

Although it took a lot of time and patience to work through these issues, like RussGLAuto and other Pierburg fans, I am very pleased with the way the original Pierburg carb operates, satisfied in the knowledge that it likely represents the very pinnacle of carb technology, in terms of drivability, performance, economy and emissions, before carbs were effectively killed off by the Euro I emissions standard in 1992.

[Brenjacques]

Thanks for that, really appreciate the write up as I'll go down the route of sorting the Pierburg out and trying it out again. I did have an electronic copy of the Pierburg manual so I'll see if I still have it, if not then I'm sure I can easily find it online again.

The waxstat on mine was almost new when I retired the carb, I found the original was slow to expand and the pin didn't push out as far as it should. Unlike yours I doubt anything was changed to compensate as once it was replaced the carb performed much better than it did previously. I still have quite a few new spares for it but really, other than it needing a really good clean and check over, I doubt it will really want for much other than a good set up. I'm sure it'll all come back to me once I start reading the manual again, I did eventually get it going quite well other than the choke but with the amount of adjustments and possibility of faults I can understand why so many give up and fit the Webers.

[RussGLAuto]

I took the easy (but mildly expensive) route and sent the Pierburg off to 'John" @ Bromyard VW for a full refurbish. He's perhaps thee best in the UK for this. He then kept GLAdis for a month while removing the Webber and sorting out a whole bunch of other issues in the engine bay as a result of many years of 'tinkering' previous owners. In no particular order:

1. The one way pneumatic valve for the brake booster slave cylinder was fitted the wrong way around. Thus, not actually providing any brake boost! No wonder those brakes felt rather vague…
2. Fuel / air separator pot missing.
3. Fuel return pipe to tank therefore left unconnected.
4. Incorrect red coolant being used thus ineffective rust prevention (VW Heritage up to their old tricks again recommending G13 red coolant for this engine!)
5. Vacuum line for the dash fuel econo-meter taken from the brake booster line (the one fitted the wrong way around) instead of from the carburettor.
6. Duel vacuum distributor fitted with retard connection open to atmosphere. So not actually retarding the timing automatically on acceleration.
7. Hot / Cold air valve in air box inoperative.
8. No vacuum connection from carburettor to air temperature sensor.
9. Hot air feed cardboard tube damaged.
10. Throttle Cable route to auto gearbox routed incorrectly.
11. Throttle Cable route from gearbox to carburettor routed incorrectly.
12. Throttle spring resistance far too strong.
13. Ignition timing set 14 before TDC (top dead centre). Incorrect.
14. Ignition Timing all over the place on acceleration, incorrect.



It worked beautifully with more power and the original 85 hp restored. The Webber was only giving out 55 hp on the rolling road test I had done! That was until the rust contaminated fuel blocked the jets the following day... which is what made me change the tank and fuel lines.

Now runs perfectly. But do remember that there is different starting procedures depending on engine hot or cold as per the owners manual:

To start from cold:
Depress the accelerator once and release to prime the carb. (twice if longer than a week since last run).
Start. Engine should fire immediately and rev to c. 2300-2500 RPM and remain there. After 15-20 seconds blip the throttle (with one’s right foot) and the revs will fall to c. 1200-1500 RPM.
Don’t wait for the engine to warm up, drive off. Once warm, she should idle at c. 950 RPM.

Which, after all the heartache and investigations, she conforms to exactly!

To start from warm:
Slowly depress the accelerator and hold full throttle down.
Start and release accelerator while cranking the engine.

Q.E.D

[Brenjacques]

Thanks for that, I may send mine to Bromyard if I have too much trouble with it. I did consider this a few years ago but opted for the weber as it was a cheaper option. Had I known I'd have found myself in this situation I'd have paid the extra money and sent it over there way back then.

To refer to point number 9 in your reply, my car has never had the hot air feed hose fitted. I ordered one and received it yesterday. Went out this morning to fit and found that in it's trips to garages over the years somebody has removed the hot air feed cover from around the exhaust and not refitted it! Annoying as it was there when I bought the car so whilst in my possession somebody has been careless and I've not realised.

I need to try and find one of these now, does anybody know where I might be able to source one or the VW part number?

Bit disheartening but it's what I'm left to deal with now so just another hurdle I wasn't expecting.

[GT_II]

To start from cold:
Depress the accelerator once and release to prime the carb. (twice if longer than a week since last run).
Start. Engine should fire immediately and rev to c. 2300-2500 RPM and remain there. After 15-20 seconds blip the throttle (with one’s right foot) and the revs will fall to c. 1200-1500 RPM.
Don’t wait for the engine to warm up, drive off. Once warm, she should idle at c. 950 RPM.

Which, after all the heartache and investigations, she conforms to exactly!

To start from warm:
Slowly depress the accelerator and hold full throttle down.
Start and release accelerator while cranking the engine.

This starting procedure makes sense for the 2B5 carb fitted to early models, which has what VW termed a semi-automatic choke. The 2E2 carb as fitted to later engines is equipped with a 3 or 4 point vacuum unit (throttle plate actuator) which takes over control of the throttle during start-up, enabling fully-automatic control of the choke.

So the starting procedure for the 2E2 is different:

Starting a cold engine
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
When it is freezing hard, vehicles with an automatic gearbox should be allowed to idle for approx. 1 minute after starting. A driving range should only be selected once the automatic choke has reduced the engine speed.

Starting 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.

That's the official version in the manual anyway. In practice, the cold starting procedure seems to work pretty well when the engine is warm as well, with maybe just a little throttle to help if needed, and I've rarely had to start it when it was very hot.

[RussGLAuto]

Good point GT_II - I didn't know the 2B5 was a semi-automatic choke! Every days a school day...

I see 7zap website is now charging to see the part numbers.

[Brenjacques]

Yep can confirm mine operated in the same way as GT_II mentioned, when was the crossover date from 2B5 to 2E2?

I've been cleaning up my 2E2 but it'll probably involve a strip down too. I'm in no rush as the weber runs well, it's when the engine is shut off that the problems start. I'm also on the hunt for one of these heat deflectors now so if anybody has or knows of any hoards of spares I'll be very appreciative of any help, I'll also post a wanted thread on here.

[GT_II]

The part number for the warm air deflector plate seems to be 055253041F, not much trace online, but there must be a fair few used ones around.

Looking through the manuals, it looks like the carb fitted depends on the engine code. The carb engines listed for UK-spec Mk2 Sciroccos are:

JB engine (1457cc, 70PS) - 1B3 carb (single venturi, semi-automatic choke), 1982-1983
FR engine (1588cc, 85PS) - 2B5 carb (twin venturi, semi-automatic choke), 1982-1983
EW engine (1595cc, 75PS) - 2E2 carb (twin venturi, fully automatic choke), 1984-1988
EX engine (1781cc, 90PS) - 2E2 carb (twin venturi, fully-automatic choke), 1984-1992

[GT_II]

I see 7zap website is now charging to see the part numbers.

7zap still seems to work for me, though I don't find the updated system user friendly.

Other online parts diagrams I have used are:

https://www.lllparts.co.uk/catalogs/vw/RDW
https://www.catcar.info/audivw/
https://www.ilcats.ru/vw/?function=getM ... anguage=en

I've also just found these:
https://partsouq.com/en/catalog/genuine ... 2bmw%3D%24
https://webautocats.com/en-gb/etka/volkswagen/

[RussGLAuto]

Thought I'd include a couple of before n after shots of the 2B5 for you. It was in an awful varnished up state when I sent it off to Bromyard, Looked almost new when John had worked his magic...