M340 STG1 Fuel System Upgrade
If you're not running our REFLEX Sequential Port Injection Kit, you'll need to activate our fuel pump relay using our non-REFLEX harness and a HOBB switch.
(HOBB switch is not included)
Our STG1 Fuel System upgrade for the BMW M340 / M40i is the ultimate upgrade for those trying to make big power. If your looking to run an upgraded turbo and run higher than E30, this upgrade is for you.
During extensive testing it was found that the factory low pressure fuel pump would experience pressure drop above 750WHP causing cars with port injection to have fueling issues. The problem only got worse with higher blends of ethanol. Tuners would compensate the injector open time to account for lack of fuel volume but this causes problems and makes it impossible to have true Flex Fuel.