MK7 hits boost then psi drops.

[LumpWizard]

So I’m pretty new to my fiesta st and don’t know all the ins and outs yet but I went to do my access port data logs for my stratified tune and when I watched the psi on the gauge for the duration of the pull in 3rd I seen the psi hit and hold 21 psi for like half a second and then it dropped a couple psi every second roughly for the remainder of the pull. It’ll go from 21 psi to maybe 14ish psi towards the end. Is this normal? If there’s anything I can provide to help narrow this down let me know and I will.

 

[dhminer]

I have no idea anymore what normal boost is on the factory turbo but it definitely tapers off. 21 psi max does sound low, though.

 

[LumpWizard]

I have no idea anymore what normal boost is on the factory turbo but it definitely tapers off. 21 psi max does sound low, though.

That’s what my tuner said and told me to submit some data logs. What’s interesting is boost seems to be consistent no matter what I do. Boost tapers off at 4k ish and builds at 2.5 ish. I noticed this as well as a airy jet engine sound after I installed a vacuum operated kompact bov from turbosmart but I’ve triple checked how I installed it and everything seems to be fine

 

[Capri to ST]

I was told by Ford Performance that maximum boost on the factory turbo is 22 PSI, and then it will boost from 13 PSI to 22 PSI at wide open throttle depending on a number of variables such as gear, RPM and conditions.

 

[dhminer]

Also forgot to ask, is this a flash tune or custom tune?