Audi Repair: 2.8 supercharged wont start, crankshaft position sensor, supercharger conversion

Question
hey buddy hope you can help, i have a 1998 a4 2.8quattro which has the pes developed g2 supercharger conversion which has been installed for the last 15,000 miles without any problems but 2 days ago i drove my car into my local town parked and left my car when i returned about 15minutes later my car would start but cut out after 1-2seconds i checked every fuse and relay they were all good when my ignition was switched on the immobiliser light came on as normal but recognises the key so promptly goes out as normal, after an hour it magically started then drove as good as it always has later that night it wouldn't start again but after 30mins it started the, same thing happened the following morning when i was bringin it to the garage. i have fuel and pressure, i have spark and compression, but now it won't start at all and my immobiliser light is coming on and turning off at the right times so i think the key and reader are ok, also tried to plug in the diagnostic but can't seem to get into the ecu, we are slowly trying to narrow the problem down but to me it's lookin like my ecu is fried or a wiring problem going to or coming from the ecu, is this problem a common occurance i've seen the same symtoms elsewhere but it seemed that the immobiliser light was flashing mine is not so i think but not sure that it's fine, thank you and looking forward to your reply
regards
sean

Answer
Sounds like you have a loose wire somewhere.  I don't think it is a bad ecu, since usually when they go bad, they don't show intermittent issues like this.  If you have spark, and compression, then your problem is fuel related, and the fuel pump usually has to have a signal from the crank position sensor before it will supply fuel.  I would check the crankshaft position sensor first.  Let me know,  Jan