My s trim kit came with a fmu. Do i still need a tune for the blower if i am running the fmu? In the installations it doesnt say anything about a tune. Do i need to tune for timing retard on 6 #s. Thanks

 

Short answer is no you don't NEED a tune.

The FMU is designed to add more fuel to the motor without the computer knowing- there is more to it but that is the basic idea.

Your best bet is to pick up a set of 42 lbs injectors and get a dyno tune to get the most out of your car. That way you don't have to worry about the FMU screwing up your A/F ratio.

 

The FMU installs on your fuel return line. The idea is when it sees boost it restricts the fuel line, this obviously causes the pressure at the rail to increase, which in turn increases fuel through the injectors.

It's going to confuse the hell out of your PCM if it sees boost when not in PE mode. The best way by far is to take advantage of the inexpensive computer tuning and simply tune for larger injectors.

You can just do a 1 bar tune for 6psi. You just pull a bunch of timing in the last cell so that it's safe for max boost.