[bmcgarry84]

EDIT: Don't mind my babble. Determined that the vehicle uses speed density instead of a MAF so this theory doesn't apply.

Let me just start off by saying that not only am I new to this forum, but to owning a BMW. I do not know everything about the N54 engine. This post is nothing definitive, just wanted to throw some ideas out there and see what other people have for input.

My theory is that a Blowoff Valve (BOV), may NOT be good for these vehicles. My theory is rooted in my days of racing DSM's, which had a similar setup as the 335i (turbo with a diverter valve). The purpose of both valves is to relieve built up air pressure from the turbo while shifting gears. A BOV would simply release the built-up pressure into the atmosphere which makes the "whooosh" sound that many enjoy. A diverter valve redirects this air BACK to the intake.

So why does BMW use a diverter valve instead of a BOV? Because the air being relieved has already been accounted for by a mass air sensor in the intake. A blowoff valve will simply remove this air from the system and momentarily cause a rich condition in the engine. This is because the computer in the car has accounted for that air already and thinks that it is there, when it is not. A diverter valve keeps the air in the intake system.

So the theory is, if you use a BOV you are causing a momentarily rich air/fuel ratio every time you shift. I have known many individuals who have switched from a DV to a BOV without any issues, and I know many people who are firm believers in sticking with a DV. The decision is yours.

Thoughts?

[Jeff@TopGearSolutions]

This car does not have a MAF so all of that theory doesnt hold water on this vehicle. So it does not matter if the air is recirculated or blown into the atmosphere. They use a DV because its less noisy and most individuals dont want to hear noises as most people dont modify their cars.

You are more then welcome to run aftermarket BOV on this car without any ill effects.

[bmcgarry84]

I see, a TMAP located near the diverter valves.

Thanks for the input.

[thebigragu99]

Car is run on speed density..