I wonder if anyone can offer some advice. We have a GTI that was having some issues starting. WD40 often seemed to work. But the problem got worse. We have changed the plugs, rotor arm, dizzy cap, HT leads. We then changed the coil. The coil we took off was cracked. When we tried to start it it started first time! Great. Took it for a spin. Great. Then we needed to go somewhere, it stalled and then it turned over but would just not fire. We called the AA - they tried with a different coil - same issue - would turn over but not fire. He checked plugs etc etc. He then determined there was no spark from the coil to the dizzy! He then tested the inputs and outputs to and from the coil - he said that all seemed ok! Now this is where it gets technical - he tested the plug that fits to the dizzy too - and said that was fine but this is a 'trigger' and it should work - no idea what he meant TBH. He then said that all seemed to be ok but that he4 did not believe that was the case and said we had a wiring problem and towed us home. We googled and from that replaced the ECU relay - when to try the car but the battery was stone dead! No charging would bring live to it. Swapped battery and the car turned over but would not start. Got a new battery and same issue - have just tested and still no spark from the coil - have no idea what to do next and would welcome some advice.
