rbh261

Just curious about something and maybe someone here has experience or data to answer this.

I understand the importance of getting more air into the engine with the least amount of restriction. I also know that the fuel pressure regulator gets its reference vacuum from the silencer box on the intake tube. With that noted, wouldn't the vacuum be lower in a less restrictive intake setup (K&N filter and elbow mod) ? If so, wouldnt the fuel pressure regulator see a lower demand for fuel due to this? So, are we hurting the fuel/air ratio by doing these mods? Is the air intake gain countered be the loss of fuel pressure? Am I over thinking things?

marko3xl3

Actually your fuel pressure regulator is connected after the throttle body, and the less vacuum you have, the more fuel it'll 'allow'. With an aftermarket intake, the only thing that could happen AFTER the throttle body is lower vacuum = more fuel, no problem.

That's why us S/C guys connect the FPR to a boosted "vacuum" line, so we can get even more fuel

rbh261

I may be missing something, but tracing my vac lines my fuel pressure regulator is connected in front of the throttle body. It's even shown that way on the vacuum diagram. I'm confused.

marko3xl3

Either way, the lower the vacuum/higher the boost, you'll get more fuel pressure, no matter before or after the TB.

But anyway, an aftermarket intake will not change anything drastically enough to cause fuel pressure problems.

The only problems that could arise are not enough fuel and too much air, but that doesn't usually happen with an intake upgrade only and if you have that problem, it wouldn't be because your new intake increased vacuum.