golf gti 1999 non start in hot weather

hi there, i have recently bought a golf gti 1999. i love this car with a passion. but as soon as the sun comes out it wont start. i have to open the bonnet, cover it in a white sheet and wait for it to cool down. i have been to the main dealer with this problem on 3 occasions and they tell me they have used all vw diagnostics on this vehicle and they cannot locate the problem. they did replace the temp sensor, but to no luck. is there anyone who could help me, i really dont want to have to get rid of my car. many thanks

It sounds like a bad electrical connection, did they ever figure out if it was losing fuel or spark when it won't start?

would u think that it may be the mass air flow meter. a couple of people have told me this. the only problem is the car dont seem to want to fault when its at vw, and when it faults at home its not registering it in the ecu so they cant tell from that either. so until i can get someone to help me out im slightly stuck. thanks for the reply.

I've heard of this problem on a new body style golf 2.0. It ended up being the ECM that was faulty. I guess since the ecm is right under the black plastic cowl pannel it heats up alot on sunny days and something in the ecm went bad.