I just recently started getting a strange problem with my secondary.

When doing a boost test the primary boost fine (10 psi) then drops to about 7 at transition but never climes out of it.

However if I give it WOT above 5500 the secondary spools all the way to 10 psi.

Anyone have any ideas on what may be going on?

Jason

 

Check your pressure and vacuum canisters, and the related check valves. If the canisters do not retain vacuum/pressure, you may not be able to get after-transition boost above the WG-spring-controlled 7 psi.

 

If the pressure and vacuum canisters turn out to be working well, then look next to the KOKO test and observe if the Turbo Control Actuator (the big one nearest the oil pan) cycles properly.

It's very common that one of the two solenoids feeding it has a failure which leads to intermittent or partial operation.

Dave