Over boost in 4th

[EgoXR6Turbo]

Have an fg turbo recently tuned. It would appear as though max boost in the high boost setting is 15 psi. It holds that in gears 1,2,3. However 4th it’s over boosting to like maybe around 16 to 18 psi at full noise.

why does it only over boost in 4th? Is this an issue for engine safety and longevity or is this sort of amount negligible?
 

its standard turbo with full exhaust including  4 inch dump and high flow cat. Plaz 700HP cooler and plaz 4 inch turbo side intake. 
 

it doesn’t have flapper mod and waste gate port as both the tuner I went with and the other one I was going to go with said it wasn’t required. 
 

the other issue I’m having is in 5th gear it doesn’t seem to want to boost past 10psi. It will if you ease it on but if your say at least 100kms you go to overtake someone and put some decent throttle in it will go to 10 like hold that for a few seconds then spike to 15. The other variant is that it’s going between 10 and 15 psi like a yo yo. Only in 5th gear no others. 
 

I did put a post up the other day on this part not on the over boosting part so I thought I would include both to see if this is potentially related as in bad tune, need waste gate ported? Thoughts?

It will also will do the same thing in 5th when your coming out of 4th at full or decent throttle

[JETURBO]

My response is the same …. Over-boost settings are too low 

Boost error is too big 

Both can be rectified within the tune… 

Over boosting in higher gears is common due to load being maintained for longer so the effects of poor waste gate design ( or lack of it ) becomes “More” apparent and this is why tuning in 4th gear is the ideal set point for not only 1:1 ratio but to use the Dyno for exactly what it was designed for and hold the vehicle at an exact rate of acceleration vs RPM to log/tune/set the correct parameters within the tune so the above doesn’t happen  

[EgoXR6Turbo]

Thanks jet. Sorry for my lack of understanding so when a car is tuned are they doing this per gear? Or is literally the  settings done in 4th and that’s it.  Because if the settings you mentioned for over boost etc wouldnt these just be the same for each gear if so why is there is discrepancy as in why does it only do it in different gears if the data is the same? 
 

I’m just trying to learn and understand what’s happening. My issue seems to be very similar to what some mention when they talk about the waste gate porting and flapper mod requirement. You don’t think this is also part of the issue at all?

 

it’s going back to the tuner this Tuesday so hoping it can all be rectified. 

 

And the other question I have is that the overboost settings will also cause both issues being the boost creep over boost in 4th and the slow boost build in 3rd and the boost Osalating in 5th?