My buddy needs some help

[420Ant2G]

Alright so I can't figure this issue out here is what he said he did and what the car is doing now
okay so this is what happened... I replaced my turbo(because it was cracked) on my 90 tsi fwd and upgraded to a big 16g and i bought a exhaust manifold as well.. so as i'm replacing everything and finishing everything up, I've come across a problem.. My car is backfiring like nobody's business and it's sounding like a lawnmower... the lawnmower part could be spake knock or something in that field... but the back fire not too sure .. so then i noticed the gas light came on... (now that's kinda strange to me that that would come on but hey i'm only a turbo dsm newb ) so i was wondering if anyone had a issue upgrading the turbo or has had this kinda problem before... THANKS FOR READING

 

[Friend-O]

At what point does it backfire? In not too sure about the gas light unless your low on gas it doesn't signal much else. If he is running stock and a bigger turbo then somewhere in the fuel supply system is an inconsistency. I cant speak for the stock fuel pressure solenoid but the aftermarket ones maintain a 1:1 ratio per psi so if hes running more boost that could be the issue. if he can get more details as to when it backfires or what he means by lawnmower then it can be more accurately pinpointed. for starters a fresh set of NGK BPR7ES would be good and a boost leak test. Low vac will cause a rich condition too.