I have a 91 IC with the fuel screw turned in two turns and a HX35 turbo.
It's been running great, but lately I notice alot more black smoke when under boost than I used to have before, just started doing it.
The truck has 300,000KM, I'm wondering is time for a set of 190 replacement injectors?

 

Turning in the fuel screw will cause more black smoke. If it didn't do it when you first turned it in you may have a boost leak somewhere which is causing you to smoke now when you weren't before.

 

Boost leak, dirty air filter, or it's just really hot and humid.

 

I pressure tested my intercooler today, it gave me soap bubbles all over the place. Looks like I'll have to get a new one.

Does anyone know anything about the replacement units from Piers?
Are they OEM replacements or are they an improved model?

 

Hook the intercooler up by itself and do a pressure decay test before you condemn it. Air it up to 25 psi and remove the air supply. The pressure should drop no more than 7 psi in 30 seconds.

 

I'll try that tomorrow and let you know what happens.

 

A gummy AFC fuel pin might hang up in the down position acting like there is no spring under the star wheel?

 

Mine has been known to stick the pin at full fuel. It started a fight with an edged 6 oh no this weekend for that very reason, he stopped chasing me (falling back) after 2 miles with the speedo buried.