Quote Originally Posted by ontarian_frog View Post
You will need to use larger injectors, and you will need to tune. A piggyback on top of the stock ecu is the way to go I believe. I don't know if you can still find the thread where exist3nce turbo'd his Optra on the Daewootech Forums. You would have to go trough a very, very similar process.
Quote Originally Posted by camopaint0707 View Post
I'm just asking if I can put the new injectors in now, without a tune. Or the pump. Or both.

I can certainly help with that lol ...

DaewootechForum.com • View topic - Turbo Optra - Now on tuned Haltech @ 225whp


As for the question, yes you can install the fuel pump. The regulator will take care of the extra flow maintaining the pressure around the typical ~45psi at the injectors. The car won't know the difference.

For the injectors themselves... that depends. What size are the stock ones? What size are these "3.4" ones? If there is a relatively small difference you can install them and get away with it. The larger the difference between them, the harder it will be for the stock ECU to cope and make the engine run normally. Also, you may get a CEL code along the lines of "system too rich" because the ECU will have to continually trim back the injector duty cycle to maintain the AFR's it wants to see from the O2 sensors. I say may because it depends on how much it has to trim... referring to long term and short term fuel trims in the OBD2 system. Without the turbo on, there is really no reason to install the larger injectors on the stock ECU.