I have recently swapped my 91 USDM NA to a S5 Jspec TII with factory turbo settings. It has a 3" downpipe and I'm still saving to get an exhaust. It starts right up and it will drive and move around. I hooked a boost gauge up to monitor the pressure. When given more than half throttle it'll reach zero vacuum and the car will stall (I've only tried this after it has reached operating temperature). Is this caused from lack of backpressure from an exhaust, rear rotor fuel cut, or what? Any and all suggestions would be greatly appreciated.

 

you have a n370 pressure sensor and ecu right?

 

I have an n370 pressure sensor and an n374 ecu (jspec, chipped with a speedlabs chip) running factory boost? still have the original vac line also, unsure what the "pill" is or what it looks like but I couldn't find anything in that line, so I just kept it.

 

I have a funny feeling you can't mix and match sensors and ecu. If you're running a US T2 pressure sensor and a J-spec ecu, it could be reading the signal wrong from vac-boost.

Edit: Just did some digging and some people say that you can't run an N374 and others say it's fine. :S

 

The pressure sensor is the one that was sent with the engine and ecu, as a complete swap. You could be right, and I also suspect it could be the ecu. I'd like to try a few things before hunting for an n370 ecu, to rule out other possibilities.

 

For Reference Only - Here is how my setup is currently running.