Hi everyone. This is my first post bit im looking for some technical info to assist me in diagnosing my issue.
Firstly, I have a 2003 Airtrek Turbo R.
For those that aren't familiar with this model, it is a JDM import Outlander based small SUV with essentially and EVO 7 GTA driveline (but a smaller turbo)
I have upgraded the cams to stock evo 8 MR ones, Evo 8 exhaist manifold, TD05HR-16G 9.8t turbo, full exhaust, Evo 7 front mount piping and custom intercooler, walbro 255lph fiel pump, 660cc squirters, wave spring upgrade etc etc...

The fault history.
Car has been great for ages. A few weeks ago we did a 2 hour trip down the highway and by the end, when we reached the city, I had zero boost. Like zero!.
It ran perfectly fine under boost, no coughing, misfiring etc. Nothing, but once it tried to make boost it just sat at 0psi and continued driving like a normal NA car. Once the car cooled down the next day it had boost again, but only low amounts (7-10psi instead of the normal 14-15psi).
I proceeded to do a full piping leak test, checked wastegate operation with an air compressor, checked turbo wasn't seized, replaced MAF sensor, Replaced cam sensor, replaced vacuum lines, replaced the air filter etc.

It now seems to boost normally, but a little later in the rev range than normal. At 5500rpm +/- 500rpm im hitting some sort of boost cut/fuel cut. Being an auto, this occurs before the gearbox changes gears. Also im reaching 8.5AFR at that rev range (used to be in the low 11's, high 10's)
I have since bought a bluetooth obd2 adapter and went for a drive. The boost reading from the Torque pro app is saying im hitting 24psi at that boost cut point, but my boost gauge is only showing 12ish.

So.
Im new to the 4g playform, but not new to turbo cars etc.
Correct me if im wrong, but the MAF is used in closed loop under boost, and the MAP is used when on boost? If the MAP was failing then that would explain the rich mixture and weird boost reading?
How do I test my MAP sensor? What voltages/pins am I looking for?
Could it be something else 4g specific that I haven't thought of?
Thanks in advance.

 

Ensure you have the correct maf installed and a functional o2 sensor and that the wires are not damaged. O2 sensor sit on the exhaust piping under the car. Check for cracks in the exhaust manifold they prone to cracking. Like the evos the boost solenoid may need a check.