Ignition problem on mk1 campaign

Hi  - looking for some help as puzzled

my car was running, but felt like it was running rough at low speed.  I read all the links and decided it must be electrical.

i changed the HT leads and the idling improved to a steady 950-1000rpm, but still had the rough running around 1800rpm or lower speeds.

i decided to change the sparks.  Everything fine, ran ok.

then decided to clean the rotary arm and points in the dizzy cap.  Here's where my problems started.  I didn't fit the rotary arm correct and turned over the ignition.  I heard a 'pop' ( probably a misfire)

The car didn't fire after that.  I decided to replace the dizzy cap and rotar arm.

I now get the car to fire, but it cuts out after I move the ignition key into run position.


i've read as much as I can find, but think its 1 of 3 things:
1.  I've fried the TCI unit
2.  Issue with hall sender
3.  Earthing issue

i don't think it's the distributor otherwise I don't think the car would fire up at all.

Any ideas?


Grez

sounds liek the ignition switch, if it fires up and runs for as long as the key is held in the start position?

quick n dirty test run a wire from the battery +ve to the coil +ve (where the black wires are) if car starts and runs fine you have a problem with the ignition feed to the coil.

to rule out ignition switch disconnect the plug from the back and bridge the red wire to the black to switch ignition on, then bridge the red wire to the red/black briefly to get it cranking on the starter (remove the test wire to coil from battery first obviously)

thanks for the advice.  That's the line I was on last night.

After more hours I was still puzzled, so Ive sent it to the local VW expert garage around here and he has diagnosed as an issue with the air inlet.  I didn't even touch this, so it looks like I've been unlucky that something on the air side has failed whilst I have been fixing the ignition side.

I'll update when I get back at weekend, still intrigued to the flat spot at 1800rpm - may have been the air inlet all along.

Just thought I'd post that problems now fixed.  The 1800rpm issue was related to dizzy cap and rotor arm and the non-start was related to a flap sticking in the air intake.

I've driven for a couple of hours today and it is the best since I bought it 18months ago.  It's 30 years old and drives like new!  Result