loud pop
 

i finished putting in my new turbo, put new oil in the motor then i started turning over the motor so i can push oil through the turbo, the car accidentally turned on while i cranked it, i immeadiatley switched it off, i cranked it once more and through the exhaust, at the end of the car is where i heard a big POP, suggestions?

How quickly did you turn it back over after you shut it off? Also what kind of exhaust do you have? Back in highschool my buddies and I used to do what we called key drops, basically drive down a street, shut the car off, and then restart it. You get a huge "bang" from the exhaust, sounded about like a gunshot. Can't remember if the FI trucks would do it, but I'm pretty sure they did.

Im guessing its a backfire. Supras are known for random pops. Im guessing ypur engine built compressiom, and as soon as you turnes the key again, it turned over.again and releaced all.the built.compression plus the new fuel thay.came in and just popped... Ypur fine bro.