So I have a little problem with my 87 TII. It runs fine when your not in boost or when you get into boost easy. But if you try to jump on it or get into power (like my last hillclimb race) it just falls on its face. It doesnt sputer or spit just falls on its face if you get over 5psi or get into boost in full throttle... I put a brand new HKS FCD and bought a used boost sensor (anyone know what the P# would be on a S4 boost sensor so I can double check it). Any ideas please help.
Info on car:
87 TII
w/GReddy FMIC, GReddy Profec B (i turned it off), HKS FCD, pulley kit, custom intake...

 

maybe theres a bost leak somewhere. does it go slower than when not in boost?

 

no it runs perfect as long as you stay out of boost or even low boost... doesnt feel like boost leak at all...I thaught it was a bad FCD but just replaced it

 

so does it stall or what? i'm not sure what you mean by falls on its face

 

it doesnt stall it just falls flat on its face...no power just loses all horse power stays running and if you lift then roll back into the throttle she will pick it back up.