ok. here the deal i got a series 4 13bt swap only thing thats been done to the car is 3 in down pipe stock turbo stock ecu w a mazda trix fuel cut defender walboro 255.
ok heres the prob.. went out today for a drive ran fine stoped at the parts store went to leave car ran fine boosted up to 10 psi and started to back fire sputter and not wanting to run worth a crap.... got home cked for the obvious vacume leak yada yada. none put a compression gauge on it fornt is reading 100 rear is reading 0... im lost motor has 30k on it.. could i just have a stuck apex seal? or anm i gonna have to rebuild this bitch

 

The -0- on the compression test tells the sad tale-

The FCD prevents the ecu from cutting fuel. The FCD allows the car to boost over the factory limit which on S4 is what, 6-7 psi? I might be wrong here, but the factory fuel cut system would have saved your motor.


Moral of the story is the FCD only comes after you have adequate fuel delivery. You were close but, uh, no cigar.

Sorry man, bad break.

 

Look on the bright side, and yes there is one.

This gives you the excellent opportunity to rebuild, even though the engine has low mileage. It gives you excellent first hand experience and opportunity to start with a clean slate.

Think positive.

 

See the following link for a quick and dirty compression test:
http://www.aaroncake.net/rx-7/blown.htm

10 PSI on an open exhaust with the stock injectors is a bit of a danger zone.