someone please help boost problem

[b5s46speed]

i just bought a 2000 s4 the boost gauge reads 20 pounds when i first hit boost then the car wont go past 6 after a little while of driving the i did a boost leak and have no leaks and i dont have a check engine light either i changed the n75 still the same i dont no what else to check

[VR4-S4]

So it will go up to 20 and as the RPM's climb the boost drops?

Does it slowly drop down to 6 or instantly?

[andru1313]

Are you chipped? What other engine mods do you have.

[b5s46speed]

i think the car is chipped it have aftermarket diverter valves and samco tbb yes it goes to 20 pounds a couple of times then wont go past 6 after i hit full throttle a couple of times

[b5s46speed]

my mechanic thinks it might be the mass air flow meter i dont think that is the problem

[01 S4]

if you can VAG it might find something hidden as your problem

[The_Jerbel]

Soft limp mode most likely caused by a boost deviation. Post some logs of VAG block 115.

[AudiSportB5S4]

yeah unless you're stage 3 boost usually doesnt get so high otherwise the K03s may just blow out of your exhaust onto the street haha. like Jerbel said you probably have positive deviation code and your ECU is saying hell no!... so if you have VAG as in vag com log away