hi i am new to the mustang world i just bought a supercharged 87 lx 5.0 it runs good but when i shift gears it backfires in every gear and at idle when reved up it backfires real bad any ideas

 

Could be a timing problem.

 

iam not sure i amnew to fords it only pops when you let off it picks up fast but when i let off it sound like a bomb went off

 

Sounds like it is running very rich. Pull the codes and fix any related problems, I would then have it tuned on a chassis dyno.

 

Definitely rich, very common on high boost supercharged or turbo'd cars. It's very hard to map a tune to go from WOT to closed so when you shift or just let off from a high rev you will get a backfire. You're supplying a lot of fuel at higher engine speeds when you're WOT and it takes a second for the fuel to stop flowing when the TB is closed so you will have some unburnt fuel ignite in the exhaust. As long as your motor was done right there isn't much to worry about. If not then you could easily blow a cheap head gasket or manifold gasket. What was the car tuned with? If you know how or know someone that could map it for you it can be eliminated but will still happen at high engine speeds. My car sounds like a 12gauge shotgun when I downshift thanks to 1100cc(105#) injectors and twin Walbro's.

 

I suggest if the car has not had a dyno tune to get one