Engine cutout with no throttle

[teenspirit7]

Hi there,

Having some problems with my (relatively) newly purchased Scirocco Mk2 GTII 1991 1.8 (No Carb conversion).

Near the end of a 30 minute journey (mostly dual carriageways), at the top of my road (luckily) she cut out, this has happened before, and seems to happen when there is no throttle applied. Usually it's no real problem and I can restart the car. However this time the car failed to start afterwards and also after a few subsequent attempts. Also about half way through the journey the car nearly stalled in the same situation with no throttle rolling in 2nd gear, I applied some throttle and she recovered.

Luckily I managed to push her into a parking space (she wasn't as light as I had imagined, esp. with a massive sub in the boot)

Anyone have any ideas? I read on someone else's thread that it could be the HT leads (any recommendations on part no's or specific link would be great), I will check their condition when I finish work today.

Thanks for reading.

[duggers]

Assuming that the engine is warmed/warming up at the time you get the cut out?

Unlikely to be HT leads as they tend to fail rather than work/fail/work etc.

It sounds more carb related as you are running a Pierberg which apparently work well- when they work!
Do a search on the forum as this is likely to have afflicted someone else.
I would also check on well known search engines for symptoms for this carb.
Sorry I can't offer more but mine is injected and the only VAG cars I had with Pierbergs were an old polo and a 1.9 five cylinder Audi Coupe both of which used to cut out occasionally when hot, I sold both of them.....................

[scrumpyone]

First thought would be the Pooberg - I had similar problem many moons ago.

Second thought would be early indication of filler neck rust. I also had this problem not so many moons ago.

[teenspirit7]

Assuming that the engine is warmed/warming up at the time you get the cut out?

Yes, quite warm after a 20 minutes driving

I tried starting it last night and it started but reluctantly, requiring some gas before it petered out, after a touch of gas it sat on the choke as expected.

Took a video (just audio really) of the start

[unknownmale]

Have you checked the condition of the rubber mount connecting the manifold with the carb? Often they split, creating a lean condition, Often when you accelerate the movement of the engine can increase the vacuum leak...Worth testing with some break clean or water when idling.

[connorj19]

This has happened to me once or twice, rolling down a hill in 3rd gear then a little throttle and was misfiring and wouldn't pick up, dipped clutch and give her a little Rev and it cleared up, I put it down to possible over fueling as there was a rich smell of petrol after, could be wrong like, been a while since it's done anyways

[teenspirit7]

Doesn't appear to be the rubber mount connecting the manifold and carb.

Waxstat has been replaced fairly recently according to car history. And the Carb support gasket/inlet man has been replaced. And the Rocker cover gasket has also been converted?

I managed to video it happening. I'm applying accelerator to keep it alive. Weird thing is after 3/4 minutes of keeping my foot on the accelerator (so it was just above idle) it cleared up and went back to normal as shown in video.

I guess the idle is too low? 750 RPM currently




I'm hoping if I up the idle a bit, say to 900 RPM, it may fix the problems.

Can someone just clarify that to do this I adjust the Idling speed control valve at the back of the Carb (not the fast idle), as documented in this guys video at 4:30:



Does the engine have to be warm?

Thanks

[james butler]

dont mess with the carb settings.
first push the carb side to side with the engine running to see if you have an air leak in the rubber manifold gasket. ive seen these replaced and split again in less then a few months.
also check your vacuum pipes which on the pooberg go everywhere so if one splits causes mayhem.
lastly check all the linkages are moving and free because if they stick can cause issues once warm.
i had a similer experience before i finally gave in and bought the weber carb and when iu took the pooberg off i discovered a pipe at the back of the carb had perished and come off. so i basically spent £230 on a new weber when all i needed was a bit of pipe.
still fitted the weber though.

[mark1gls]

Yes 750rpm is a little on the low side, 950rpm is where you want to be but I don't know how you adjust a pierburg carb.

[teenspirit7]

Took it to a the garage its always gone to (with the previous owners as well), they fiddled around and 'upped the idle' however made the problem worse. (thank god they didn't charge me)

Then took it to a old chap who runs a old VW specialist garage, and he completely re-tuned the carb. Mentioned there was an air leak. Seems to be running v well now. Idles around 1000 drops to 750ish with full beam, radio, fan etc.

He mentioned the Distributor was worn and the rotor arm was a bit loose, said it should be solid, said it needs replacing soon

Where should I start to look RE distributors? Can't seem to find a new one from BOSCH or the french brand which escapes me at the moment. Should I look into refurbing the current one? Haven't heard great things from the cheap ones from GSF etc.

Cheers

[teenspirit7]

Unfortunately problem still persists. Anyone think the Distributor could be to blame for this issue? Trying to track one done atm

[bensspares]

Hi, I read about your plight.. It's fuel starvation... Nothing to do with the electrics.. The millage is far too low for dissy wear.

Check the inline filer by the rocker cover for particals of rust. Also when you are experiencing this issue feel the fuel accumilator on the front of the head. If its warm then its definatly fuel starvation.

[james butler]

im quite suspicious that your idle is dropping with all the ancillaries on.
there is a diaphragm on the drivers side of the carb towards the back with a plunger that touches the throttle arm, this increases and decreases throttle position in relation to manifold pressure and regulates the idle, so if its not working then this could well be your problem. but if the old boy says you have an air leak then thats the first thing you need to fix as the carbs accuracy depends on it.

[110%]

I've had just about every running issue with my MKII 1.8EX. I found that most electrical issues killed the engine completely, where as with air leaks or fuel starvation, the engine was recoverable from low revs.

I would reiterate what others have said on here and suggest checking the rubber carb mount for leaks; check the inline fuel filter in the engine bay; and finally take the rear seat off and check the tank filter which is attached to the fuel gauge. This often gets clogged up with rust from the filler neck and then un-clogged by itself when pressure drops only to get clogged again.

[bensspares]

Has this problem started since the weather has got colder ?