Re: Adjustable Fuel Pressure Regulator (archive)

You are thinking of a rising rate fuel pressure regulator that is referenced to manifold pressure - like the ones used for cheap supercharger systems. An adjustable fuel pressure regulator does increase fuel flow through the injector per pulse width by increasing the fuel pressure in the rail. And you are correct, the Motronic will correct most of the time thanks to the oxygen sensor. However, at wide open throttle, the ECU ignores the oxygen sensor and goes into "open loop" mode, where the fuel maps embedded in the EPROM determine injector open time (pulse width). Thus, more fuel at wide open throttle.

However, unless the car is running lean thanks to improvements in airflow, there is really no need for an adjustable fuel pressure regulator.

I personally don't suggest using it unless you need more fuel, in other words, is there a point during your driving that the car is too lean and the stock Mototronic can't compensate? I'm also a little dumb about the theory, if you modify the fuel pressure higher and the ECU gives the in jector it's regular duty cycle, the result is a richer than normal mixture, the O2 would pick this up and the car would lean it'self out (unless under WOT (wide open throttle)Oh wait a min, I guess I just anwsered my own question. Wait no I didn't, under WOT there is no Vacume, so help me understand how this works guys.

Brian

Hi everyone, want to ask those who have had any experience with this item:

>What is the benefit of installing this product (performance, economy, etc...)

>What is the best on the market, price not an issue?

>Does it work best when in conjunction with other items (exhaust, ported manifolds, airfilters, etc...)

Thank you all for your input.

Follow Ups:

[ Follow Ups ] [ M5 (E28) Message Board ] [ Msg. Board FAQ ]

Questions, comments, or problems, please visit the Roadfly help desk.