Mk2 Scirocco 1600 GT misfiring and stalling at high revs

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F514HMJ
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Mk2 Scirocco 1600 GT misfiring and stalling at high revs

Post by F514HMJ » Thu May 25, 2017 6:10 pm

Right, I'm believing that this is a fueling/lack of fueling issue

Firstly the car in question is a 1.6GT Scirocco mk2

It has the 1600 engine and has recently had the following work completed

1.8 golf cam fitted
Timing belt done
Water pump
Thermostat and housing
Spark plugs
Ignition leads
Distributor cap
Rotor arm
New fuel lines
New fuel filters
New oil
New oil filters
New antifreeze
New rocker cover gasket

There's quite a bit more but I can't remember all of it,

Here is what happened , I've done all the work myself and the car was running absolutely fine, ran brilliantly infact pulled like a train great through the gears etc etc

One night I'm out with a friend and I spank her a little bit, she starts misfiring and what not, strange, so I pull over and all sorts of nastyness had happened, most notable of which was the alternator belt being upside down but still somehow on all 3 pulleys , so I eased her back to the unit, upon closer inspection I find that the timing belt was loose and had appeared to jump 6 teeth.

So I timed it up the exact way I did before and it wouldn't run, back to the drawing board and timed up using the Haynes manual, started her up and she ran first time on the dot.

Now taking her out for a drive you can drive her sensibly but if you stick your foot down and go about 3-4 thousand revs you get lurching misfiring and cutting out, wait a few mins and turn her back on and she runs fine, however it's the same situation, build the revs up too much or stick your foot too far down after coasting and she acts like a pyjama.

Now here's the part that is making me think it's a fueling issue, someone said to me to try running just a fuel line to the carb, I didn't have the adequate piping to make this happen, so I put a kink in the return line and a cable tie to make sure it was closed.

Took her out for a drive and suddenly I'm getting juddering and a bit of misfiring at low revs but she's loving being spanked, all the way to the redline and it takes it fine, but the moment you drive normally it is misbehaving again, however if you pull the choke out it makes it better (choke out = higher revs which in turn = better running in this situation)

So this has left me a bit bamboozled , there is a lot of people saying to me to replace this or that but I'm not prepared to start throwing good money after bad. I need to diagnose the faults I have then I'm prepared to throw some coin on the table and buy some shiny new parts.

If anyone could help me it would be much appreciated , I'm very new too this and I'm still learning so please bare with me.

Regards

Sam



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unknownmale
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Re: Mk2 Scirocco 1600 GT misfiring and stalling at high revs

Post by unknownmale » Thu May 25, 2017 7:48 pm

Which carb do you have?


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Re: Mk2 Scirocco 1600 GT misfiring and stalling at high revs

Post by the edmundator » Thu May 25, 2017 10:28 pm

How is your filler neck?
Have you had a look in the tank for rust and other debris?

Cheap and easy things to check that can cause this kind of problem.


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mark1gls
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Re: Mk2 Scirocco 1600 GT misfiring and stalling at high revs

Post by mark1gls » Thu May 25, 2017 11:18 pm

Rubber carb flange split?

Wobble carb and see if running changes.

Do you have a standard set up on the carb or any mods?


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mark1gls
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Re: Mk2 Scirocco 1600 GT misfiring and stalling at high revs

Post by mark1gls » Fri May 26, 2017 10:34 pm

Do you have the carb set up for a 1.6 if you have a Webber as it's a smaller jet in a 1.6 compared to a 1.8?


Mk1 78 Scirocco GLS 1.6 FR, weekend toy.
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Jerry Atric
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Re: Mk2 Scirocco 1600 GT misfiring and stalling at high revs

Post by Jerry Atric » Sat May 27, 2017 11:06 am

Just my two pennyworth.....

pulling the choke may increase revs but basically you are increasing the richness of the fuel/air mixture by introducing more fuel.

You've already said that with your "mod" the car ran better albeit lumpy at low revs ( most likely because the mixture was TOO rich )

Regarding issues with rust contamination....if you have the carb engine, then I'd expect you have a clear plastic filter inline somewhere so that should show you if you have crap coming through the system I'd have thought.

So my guess is a blockage in one of the jets in the carb, or maybe a rubber hose perished ....when you put your foot down, drawing in more air , hose constricts, loss of power. Turn it off the hose opens up again, and the engine runs ok until the next time you put your foot down.

Certainly sounds like an issue with achieving the correct fuel/air mixture to me.



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Re: Mk2 Scirocco 1600 GT misfiring and stalling at high revs

Post by the edmundator » Sat May 27, 2017 1:06 pm

There is a filter at the end of the fuel pick up in the tank, so rust doesn't necessarily make it to the in-line filters.


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