Overboosting and Fuel Cut

[YO ZAH]

Hey Guys, this one's a bit of a long read
I've been facing this issue for nearly a year ever since I let my car sit for a couple months, I have a 2007 1kd 330000ks, and it keeps overboosting (no code) it happens 100% of the time, I am running a FMIC, Uni X chip, 3 inch Exhaust and Blanked EGR,
the problem is that when I'm driving it performs Great around 15psi on my gauge but if you slowly keep putting your foot down the boost will fly to 25-27psi (holds this boost) but has no extra power past 15psi mark, if I quickly put my foot all the way down the Map Sensor I'm assuming corrects itself and pulls back to 15psi where the fuel kicks in as well (you can hear this though the snorkel and exaust) but will start doing this process again right after
It has great power down on the low revs but soon as you hit mid to hi revs it begins to have issues unless you floor it then the car corrects itself for a minute giving you the correct amount of fuel, it can be a pain on the hills because the boost winds itself to 25psi but isn't fueling enough so I'm having to put my foot down to correct the fueling

I have Checked all vacuum lines and pulled the throttle body off many times to clean and inspect, I have tried different Map sensors 2 bar 3 bar and 5 bar and they all have high readings above Atmosphere which in turn make the car throw a P0069 and P1251 which I assume is related to the pressure differential
Iv replaced Map,Maf and Iat sensors, cleaned my intake manifold, pressure and smoke tested my intakes(no leaks)
This high boost started happening when I Blanked the EGR because the EGR was staying opening and leaking/fluctuating boost but if I unplate the EGR it seems to still be leaking and hitting boost cut at about 12psi Aswell, so its lack of power vs overboosting....
it is a very weird situation my car has been driving like this for nearly a year now and my egts are sweet and haven't had any problems other wise, Injectors are fine, rail pressure and fuel system is fine, question mark on the stepper, map and maf sensors but can't seem to find the solution with those yet, I'd put a question mark on the unichip and tunes but they were operating for 3 years fine before this

Things to note, when I clamp my 3 bar map sensor with a 4.7v zener diode the car performs great, until I get high in the revs and boost and puts my car into limp mode with P0069 and P1251,
This Map issue is very weird, I have 2 OEM Hilux Map sensors one brought online and one from a mate they both read nearly 200kpa at idle which is double the Baro reading, my 5 bar map sensor will read 135kpa at idle and my 3 bar clamped will read 125kpa at idle the only sensor that works is the Map sensor that came with the Luxy and it reads 91-95kpa at idle,
Maf without EGR module will read 17-22g/s, with EGR module will read 7-9g/s at idle (EGR Module is to stop code being thrown)

so Im at a brick wall at the moment
I'm thinking about a retune to try get the boost down or fuel to match but don't want to go get a tune if something is going wrong in the engine bay

[Bushwalker8]

You haven't mentioned the obvious step of trying to back out to rock-solid standard ECU programming.
Boost pressure is maintained by the variable nozzle which is electrically controlled by the ECU, big hint there.

[YO ZAH]

You haven't mentioned the obvious step of trying to back out to rock-solid standard ECU programming.
Boost pressure is maintained by the variable nozzle which is electrically controlled by the ECU, big hint there.

Sorry I forgot to mention that I removed the unichip back to stock ecu with the EGR plated and Un-Plated
Was no change at All, I'm on to something at the moment with the EGR I suspect it may be leaking on the air intake side, fingers crossed with this one

[Reginald]

Did you ever resolve this issue?

I've got a very similar problem where I get over-boosting (with no additional power) with light/medium loads and have to put my foot down in order for it to correct. It started happening several months after putting in a EGR restriction plate. No codes.

[walledroof]

Hey! Have you tried resetting the ecu completely? Sometimes helps with weird boost issues.

[walledroof]

My friend had similar issues after egr delete, turned out the blanking plate wasn't sealing properly. Might be worth double checking all the seals?