HELP NEEDED !!! 4g93t GDI

[BoostJunkieXL]

Good Day Tuners,

I have a slight problem ( I hope ) and I'm in need of some guidance. 4g93gdi turbo engine. MAJOR loss of power in the lower end of the power-band. car takes forever to accelerate to 50kmph (driving at a steady pace) then rockets off from above 50kmph. If I take off from a stand still while giving more gas i.e driving hard, car works fine. Also car stutters as though its gasping for air when it tries to change gears on auto mode. from 2nd to 3rd it stutters and "bucks" I have to either press down harder for it to gear down and shift therefore driving hard for no reason from a steady pace. or release the throttle and then go back on it hoping the gear changes right this time. car works fine on tiptronic minus the loss of power. I also need someone who can source and install piece of the harness that leads to the compressor (its not getting power, tried everything and my mechanic came to that conclusion), as lines had already been vacuum and gas was topped up. car works fine otherwise its just this issue and the lack of AC has my girlfriend and my mom on my case 24/7 and my current mechanic is too busy at the moment. I'd appreciate if anyone can share some insight or point me to a mechanic who can assist preferably someone who isn't biased against GDI technology with experience working on these engines.

Thanks in advance

[trini iceman]

This sounding transmission related.

[BoostJunkieXL]

hmmm...thanks ill look into that

[xtech]

Plug in a paperclip scanner an read of the codes that pops up on the dash for the engine.

If no idea what a paperclip scan is there is an explanation here...

viewtopic.php?f=25&t=294415&start=210

[BoostJunkieXL]

i have an ELM37 with torque pro . i get these two codes

P1515 Brake Vacuum Sensor
P0425 Temp Sensor (bank1) i know this one is due to my exhaust where the sensor is supposed to be theres no way for it to connect to my exhaust as the stock exhaust is still installed and my stock exhaust didnt come with it :/

the brake vacuum sensor i believe is something to do with my brake booster. ( so i was told )

but ic an try the paperclip and see if any codes come up.

Thanks

[Mercenary]

why u went with that engine. u like headache.

[nissan4life]

BoostJunkie on your first read this sounds like a transmission related problem but as you just posted the codes i see you have P0425.
This code relates to the exhaust re circulation temperature sensor (egt probe) and works in conjunction with the ecu and transmission hence the bucking and lost of power.
The ecu will read this code as an malfunction from the catalyic converter and put the tranny into safe/limp mode, this is to protect the car from potential problems. I experienced this yrs ago when i first bough my 4g15 gdi and the previous owner cut the cat off, i had lost of power on anything over 3000rpm
see post and start here to see if this helps.
viewtopic.php?t=420913

[BoostJunkieXL]

tuners thanks for all the advice....got the problem sorted out a little while ago but forgot about this post...it was as simple as..........boost leak ! intercooler hose has a tear in it....other than that engine works great !!!