Need diagnosis recommendations engine light and gearbox jumping plus misfiring

[Robinhood]

Hey fellas new owner here and really need some opinions on what auto electric guys and gearbox mechanics automatic should be looking for to fix this car i just bought any help appreciated. 

1-test drive car and it changes gears into second really hard and erratic on change down scanned car cam up 1772 lc solenoid also maf code 

2-Car is pinging on acceleration sometimes mainly second gear and at idle popping through exhaust. Seems to drive smooth though did have like a spark breakdown at high revs on test drive 

So drove home from brisbane the lights on dash in background flickered once the slip is displaying on dash and vdc after pressing holding button it does not turn on or off

Took it to automatic place he drove car with scanner connected and it popped up speed sensor maybe in auto box or he said something with the abs speed sensor. He said he wanted auto electric guys to check it out as its coming up all these codes. 

I am taking the car to the auto electric guys tomorrow and asking anyone here to help me with suggestions on how the auto electric guys should start diagnosis. 

I used to race quarter mile and built a few race cars carby but have no idea on these skylines but love the shape and setup so hoping someone can give me help before i start blowing money on trying to fix it. 

I know heaps of problems but any suggestions on where to start or simaliar problems others have had cheers !

Car has 2.5 inch staunless exhaust big canons on rear and a round mushroom style pod filter other than that i cant see any other mods 

[KiwiRS4T]

Not easy to mod so pod filter and exhaust probably it. Would have thought transmission shop had a scanner. Ring the auto electricians first and see if they have the Nissan Scan tool - otherwise you might need to go to a Nissan dealer.

[Robinhood]

I would have thought with air filter and exhaust it would not really throw out gearbox problems with erratic changes and severe shifting second gear but is this something others have had dramas with ? Giy at automatic shop did have scanner attached threw up speed sensor he said . When scanned the 4 days before had lc solenoid maybe had speed sensor as well. He said it is weird throwing all of these codes and before he drops the pan on the box wanted me to take to the auto leckies

[Robinhood]

Car fixed from 3hrs diagnoses auto electrician earth wire on ecu main computer so if your gearbox is changing hard through gears or jumping into its changes also throwing heaps of codes it could be this. Motor was pinging detonating rattling and misfiring at idle . Now no problems revs clean changes gears no trouble codes. I was nearly about to buy a gearbox for this car .accelerate auto electrics sunshine coast can diagnose even the hardest of problems with skylines! 

[KiwiRS4T]

11 hours ago, Robinhood said:

Car fixed from 3hrs diagnoses auto electrician earth wire on ecu main computer so if your gearbox is changing hard through gears or jumping into its changes also throwing heaps of codes it could be this. Motor was pinging detonating rattling and misfiring at idle . Now no problems revs clean changes gears no trouble codes. I was nearly about to buy a gearbox for this car .accelerate auto electrics sunshine coast can diagnose even the hardest of problems with skylines! 

Good to know!

[sonicii]

with multiple problems with seeming unrelated systems, power/earthing should be the first place to look.