Well ive had this problem for about a year and havent figured it out.
As soon as the car starts to hit boost it leans altheway out and just goes "puh!"

1989 Fc
TII swap
NA harness
FMIC
3" turbo back
AEM wideband

Things ive done to try and fix the problem:
Fuel pump
AFM
ECU
Fuel filter
Take out wideband and put o2 back
Take out 720cc secondaries and put stock injectors
Take turbo off an copper gasket everything.

This was supposed to be my drift car last year and now im ready to just give up and part it out or sell it for a fraction of what i put into it ;,( someone please save this Turbo widebody beast from doom!

 

fuel cut defender. Get one
or rtek 1.7 ecu chip to pair with those injectors.

 

I did have a rtek 1.7 with the injectors but i just put a stock ecu and injectors trying to isolate the problem.

 

Another important note!
When i first got the swap running it ran great! I took it for its first run all was good till i poped a intercooler pipe off during boost. After i put it back on the BOV never worked again, i tryed replacing it and nothing. Car still boosted prety good but kinda bleed off when you try to hold it in boost. A few weeks later the lean problem came and ive been going through hell trying to figure it out for the past year

 

I dont know to much about the turbo aspect, But is it possible its a Sensor? boost Sensor? or Vac problem?

 

Any other suggestions??

 

Yea, Im gonna second that you still have a leak somewhere.

 

Have you tested your secondary injector wiring?

 

if you went rich with boost id guess air leak, but going lean would make me think a fuel problem...

 

How do i test them?

 

Ground the injector signal wire at the ecu briefly. Ignition switched to 'on' but engine off. Listen for the click as the injector opens and closes. Sorry, don't have the exact wire colors handy. They're in the fsm.

 

i did an S5 t2 once that ran ok in the 0-3500 range, but over that it would lean way out. the fix was weird because nobody else seems to have this problem/solution, but anyways.

i checked the codes and since all the emissions stuff was gone it had a bunch, but one of them was the fuel pressure regulator solenoid. so i plugged a solenoid in (don't worry it was just plugged into the harness, no vacuum lines were involved) and the AFR's went from 14:1 and going leaner @3500rom to mid 12's.

so i would try that.

 

Nice!!! Where and what dose the solinoid look like??

Thanks for all the imput guys i realy appreciate it!