3406E warms up looses boost ?

[Bengy88]

35-36 psi boost on a 3406e is healthy. It’s not unheard of to see up to 40 on them with the higher horsepower engines but anything over 40 and I would be figuring out what’s wrong. Anything below 35 and I would also be figuring out what’s wrong. Could be anything from a boost leak, worn turbo, bad wastegate (I’ve seen a ton of them rust out), or as mal4shtf said your fuel check valve. If your engine can’t perform properly then it’s not gonna spool your turbo properly.