Car stalling

Hi all, I have a mk1 vw golf GTI, 1991 cabriolet. I seem to be having a problem with it as once it is warmed up and fan kicks in the car starts to struggle and cut out as if no fuel is getting to the engine side. It could be something else but when I give it gas it revs up no problem but as soon as I release the accelerator, it stalls, but starts up straight away no problem but still want to stall when ever I come to a stop at lights or a give way. Anybody have any ideas why it is doing this and what I can do for it to stop it doing this all the time. I know the Co2 is at 6.55 and tried to adjust it down but wouldn't come down as I expected it to. The lowest I can get it to is 6.5. Any ideas how and what I can do here. Thanks in advance.

what fuel system, carb or Digifant?

Digifant, 1800 GTI, on H reg.

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Test your CTS sensor as that can cause issues, as they are fairly cheap I usually replace it out of hand as they can cause hot start as well as cold start issues.

Another thing you want to do it to do the residual pressure tests if you are losing pressure then this can cause the injectors to act wonky, it will eliminate the Fuel pressure regulator as a cause.

My buddy Ron has a great how to on static timing the Digi Cars with nothing but a DVOM.

Static Ignition Timing on VW A1 and A2 DigiFant Engines.

You basically place the car in time then look at your hall signal for going high to low.

If yours has a Catalytic Pervertor then you may have a wonky o2 sensor…


Now the Basics are that you have eliminated all vacuum leaks as unmetered air is a pain, and don't forget the idle by-pass screw as if you can turn it with your fingers then that is a air leak and you need a new o-ring…count the turns to remove it, write that down.  Run to a good hardware store and get a new one, then also wrap the threads of the Screw and THREADS ONLY with telfon tape as that will prevent future air leaks.

Otherwise I would be suspect that your ISV could be causing issues but they are pricey, and you want to eliminate the easy ones first.