try your relay. If it's still not working, revert back to stock and have a tuner check out your maps...given that your tune was done properly

 

thank you to everyone for your input and help, seems the problem may have been the RELAY. i replaced the stock one with the Blue one and presto, uber rich stock tune and a great running custom tune.

on a side note, i am pretty amazed that this issue was caused by the relay. i figured if the relay was the issue that it would not have cranked at all. i never thought that it would only screw up under boost, or actually due to voltage more than likely. anyway thanks again, and i hope someone in the future finds this thread helpful.

 

The relay controls the low voltage / high voltage that is sent to he fuel pump. It's normally in low voltage. If it doesn't kick into high voltage under high load, your car goes boom.

 

yeah, pretty **** design from Mitsu..

 

Im getting my evo x soon. Can someone please direct me where on the car the relay is along with a place to buy the new correct relay (and what exactly the correct relay is)

 

here is a picture showing the relay location.



from post #53 in this thread.

https://www.evolutionm.net/forums/ev...-page-4-a.html

 

This is perfect. Thank you very much!

 

im having problems at wot between 6k to 7k almost always in 3rd and 4th gear, the car will stutter... could this be the cause of a bad fuel pump relay? the car is brand new 2014 gsr completly stock with ruffly 1300 miles on it any help would be much appreciated

 

This is probably a stupid question.
But I have seen people neglect this portion quite frequently.
Was the wideband properly calibrated to open air?