Hey all. Ive got a 90 EF sedan with a Z6 and a greddy 15G turbo kit in it. I'm running emanage blue and am currently on 8 psi....my question is this-

I have adjusted my wastegate to up my boost and it climbs to 8.5 and then bleeds back off to about 6. 8.5 is not a spike tho. It should be getting to 9-10psi but it hits 8 and then bleeds back off. I'm performing a boost leak check on thursday and have a sneaking suspision that my diverter valve is leaking....its leaking at idle also, but i dont see anything wrong with the since it's a 20VAC at idle on the gauge. but it should definatly not be leaking in boost. Could this be the reason for my boost bleed off? any help would be greatly appreciated. trying to narrow this down asap

 

or the actuator can't hold that pressure. What happens if you add a manual boost controller? When boost backs off like that, it means the rod can't hold the flapper door closed.

 

We're going to throw a hallman pro mbc in after we do the leak check and see of we can control it that way. I'm going to back the wastegate actuator off before we do it so it takes that out of the equation. I was also doing some reading and came across something that got me thinking, the flapper may be cracked. I'm going to check that as well but I find it unlikely. Any other thoughts?

 

If it was cracked it would be a very small bleed-off of maybe less than what you're experiencing. I'd be more inclined to think that as a LAST resort possibility.... (Possible, but highly improbable)..

If its cracked, worry about crossing that bridge when you get to it. Also check your manifold and turbine bolts. small leaks can occur there too.