installed the APS single, had a problem holding boost, so i got a free flowing exhaust and sent the unichip to tuan to get it reflashed for the 93 tune and some custom map stuff. well after i put the unichip back in the car does the exact same thing. boost climbs smoothly and quickly to about 10psi at around 3200 rpms and holds---until 4500 rpms, then it dies quickly down to about 5psi at redline. if i change gears before 4500 rpms the boost stays around 8-10. but once it hits 4500, down it goes. this is even after my reflash.

so i call tuan, he says to disconnect the boost controller which i do, and i only get 6 psi. tuan now thinks i have an exhaust leak before the turbo causing me to lose boost.

any suggestions? phunk? anybody?

could this be a bad wastegate spring?

 

Didn't he have to change actuators to get the boost to only drop 1 PSI on their car. I mean I know its a stock exhaust and all but I thought the boost drop was programmed into the Unichip. Are you sure its mapped right?


Edit: This is not a flame I'm just asking. Maybe you need a different wastegate actuator to hold the boost? Or make sure he really did change the boost map in the Unichip if its mapped like that...

 

well i really wondered if he just didnt save the changes by accident but i called and spoke to tuan and he reassured me he changed everything in the maps. im not sure about the actuator deal.

 

Talked to a couple more guys. With the solenoid boost reference off...and relying on the actuator springs to regulate boost. If it still does it then it should be the actuator that is the problem. As well...if it is adjusted improperly and it us too tight it will still bleed boost even if the solenoid tells it to back off to build boost.

 

Tig,

Does the boost stay at 6psi across the RPM range with the solenoid disconnected?

 

yes, it stays at 5.5 to 6. but thats also what the boost drops to with the solenoid hooked up.

 

So maybe its the solenoid leaking boost signal pressure and not holding closed