Problems with power

Testing in progess i am starting to feel like maybe something is loose and having bad contact... Because it can change during driving and sometimes when i turn off the engine the problem goes away and rarely it dont go away

after changing the distributor cap and rotor and driving the car made for like 20 minutes very massive stalling. I mean when driving, it was like suddenly hitting brake. and in under one second it was going again, and then it made it again, and after 20 minutes it was over

where did you get the bits? perhaps they arte incortrect for your car. I do most of my shopping here:
AVS Car Parts - [The VW - Audi - Seat - Skoda Parts Specialist]

get new leads as well if old or unknown make

well they should be okay quality. i have bought many things from them for many cars. Rotor and cap made by bosch i think..

can you double check the application, make sure they are correct for your car. there are a couple parts available for the digifant plus they might have sold you a random one for another model

Well no visual differences. Let see..

hello its seems to be that i have problem similar than in this video VW A2 Idle / Closed Throttle Switch checking.... - YouTube

anyone know can i get that part separately  from somewhere ?

Well the switch that he is pointing out is the WOT (wide open throttle) switch.  The Throttle position switch is on the bottom of the throttle body, and is a go/no-go switch that you can test… Same as the WOT switch.

With it unplugged, you simply use a DVOM, and measure for a short/open when the Throttle Butterfly valve is open/closed.

This is only applicable to the 90ish Digifant.

Bigger issues are Timing, and Vacuum leaks.

an eassy way to test the wirign back to the ecu is hold the throttle just off idle say 1.5k rpm, then press the WOT switch. if the revs drop to idle and then rise up again when released then you know everything is fine from the ecu side of things.

this doesn't test the idle switch itself, as above use a multimeter or a test light for that

well my bad english made me understand few things wrong, sorry for that. It seems that those things are okay. but now i find out that my knock sensors wire doesnt look great, rubber is missing a lot from the wire.

Any ideas what is the right colour for the sensor, because when i look them i get usually green ones, but this one that i have is white one ? any differences ? Knock sensor should do something to timing and other stuff ? Because 98% times when i start the car again it runs great a while and then the problem starts.

the colour codes just tell you the wire lengths, as long as the wire reaches its fine. OEM one is blue, you can usually grab one from mk3/seat/audi 2.0 8v in the scrappy

New knock sensor coming, lets see what it does, grounds are also looking nice and clean. Is there a way to test the fuel pump relay and pump ? Because i dont hear a loud noise from it so maybe the relay has problems ? Oh and been looking pictures and in many cases the blue coolant temp sensor is the nearest one to the block and mine is not ? Does this even matter where it is. See the picture i sent earlier.

Petrif91 said

New knock sensor coming, lets see what it does, grounds are also looking nice and clean. Is there a way to test the fuel pump relay and pump ? Because i dont hear a loud noise from it so maybe the relay has problems ? Oh and been looking pictures and in many cases the blue coolant temp sensor is the nearest one to the block and mine is not ? Does this even matter where it is. See the picture i sent earlier.

IF you can't hear the fuel pumps Prime for 4 seconds prior to start, then suspect the Fuel Pump Relay first.
otherwise you don't hear the pumps run normally, just the initial prime, that is turn the key to run, not start will all the accessories off, and you should hear them run for 4 seconds.

The Blue CTS sensor doesn't have a preferred location, it could be in the front of the flange or to the rear of the flange….Just make sure that you have the proper plug on it, blue for cts, and black ro the Water temp senor.

Hint,  You may want to buy a new flange and keep it spare as the plastic ones break at the mounting ears at the most inappropriate time.

or

You can replace the plastic flange, with a metal one, and use the CTS, sensor off a 16V and a temp sender.  (best thing is they never break, and the 16v CTS seems to be better made and not as prone to the flakiness of the blue.

See: How I hate Plastic parts….
I still hate plastic parts, but thanks Tolusina. | VW Vortex - Volkswagen Forum

the euro 16v ecu sensor is no good in an 8v, its M10x1 thread but the hole size is M14x1.5. what you need is the early digifant one

parts list:
027121133A - front flange
049919501 - dash temp sensor
035919369M - ecu temp sensor

Okay, so changed fuel tank cap, and knock sensor and checked also some grounds. i Was on vacation also for a while, drived today 100km without problems. Lets see is it all fixed now or not

if you still have problems I would check the filter and vent in the fuel tank

Still working, very strange if it was only the knock sensor..

You have to remember that the knock sensor is a peizo/electronic microphone.
It is listening for knocks and pings, then tells the ecu to adjust the timing either advancing it or retarding it.
If it is Bad, it can go to always retarding the engine, or advancing it to be out of range electrically.

They do go bad from time to time, and diagnosing them is well as you found out, hard to do.

 

Thank you for all of you guys