Audi Repair: problems after crash repair, crash repair, battery terminal

Question
hi,i have a 2006 s line a4 2 litre petrol turbo which has had a front impact collision, i was hoping any of you knowlegeable people might throw some light on whats going on with it since it has been put back together , it wont take throttle above 2500 rpm,it pops and bangs,i was thinking maf/airflow,etc my local friendly snap on man hooked up his modis diag machine to it yesterday,the result was as follows:1 and 4 misfire detected, air mass meter g70 power supply intermittent,cooling fan circuit, power supply battery terminal 30 voltage too low,cmp/sns speed sensor bk1g28 incorrect correlation, crash switch off has been removed, drivers and passengers upper limit reached 00654 00655, also the engine is extremely tappety! is this normal?car has only done 3000 miles ,now i understand the gist but some of the diagnostic language im finding confusing and was wondering if anyone who is more used to this language could give me there opinions ,thanks

Answer
hello
sorry about your car. Most of the time after front collision, if it's hard , timing jumps. With misfires faults and cmp/sns speed sensor bk1g28 incorrect correlation , more like it that's what happen in your car.
During very hard collision  engine stops so quick and jumps timing or bend valves.
So, make sure timing is correct if not install new belt ,clear all the faults and see how it runs.
good luck                 pltech