My friend has a 1.5l jdm zc in an 89 ef converted to obd1 that he turboed, on 7lbs. Once it starts to build boost it leans out and starts stuttering. We tried two different fmus,It has a missing link, we changed the fuel filter, and fuel pressure regulator ,we put a walburo fuel pump in it, colder spark plugs that we gaped to .30. I just doesnt seem like its getting enough fuel when it gets out of vaccum and into boost. We have tried everything we can think of.....this is the first turbo we put on also.

 

you tried everything but ditching the fmu. At the very least get a safc and run a map hack. Missing links and fmu's are trash.

 

yea i know, but it still shouldn't lean out in boost though. We have tried everything that we can think of.

 

get a tune that would solve ur problems

 

How did he tune it?

 

what tune?

lol

 

Thats what I was hinting towards.

 

internal or external waste gate, if the vacume hose is wrong than it will do that

 

come on people tell this guy he didn't retard the timing far enough
duh.............
retard the timing dude and you'll be ''GOLDEN''..........if not more retarded

 

It wouldn't hurt! As it's already lean, and severely prone to knock....

More likely, it's caused by the FMU not providing any additional fuel for the first 3-4 psi of boost. I highly doubt they spent the additional $$$$ to get a spring-loaded FMU that doesn't have that problem. And, with little or no tuning, and most likely a T3/T4 57 trim, and stock injectors.....
The poor thing wouldn't have enough fuel if they ran 100% duty @ 100 psi....