noodlerooney wrote:For N/A engines, do Jim's fuel pressure regulator mod, it's FREE!
Writeup is on Camryman's Passing Lane under the Solara forum.
For an N/A engine, I would not do that fuel mod. The 43psi from the factory is a good recommended pressure. It is also the pressure the rest of the fuel system was spec'd at like the fuel injectors.
The reason to do the fuel pressure regulator mod is when you have a boosted application. The stock fuel system is fine for no boost but when you start hitting pressure rather than vacuum, it works against fuel delivery. You need to increase fuel pressure accordingly to keep up with the pressure. The more boost/pressure, the more you increse the fuel pressure.
The Risk:
If you haven't done anything to increase the air into the combustion chambers and you now increase the fuel pressure, you will increase the fuel delivery. The ECU can correct for it and will automatically. The problem is, you've now changed the balance of the system. If you check on an OBD2 scanner, you'll see the a negative correction for a rich condition expressed in %. If you imbalance the fuel delivery too much (around 18% I think), it will throw a CEL. This means that the ECU is not able to correct it far enough to deliver an optimal fuel ratio. Since it should have the ability to correct for normal changes like altitude, it will assume something is malfunctioning.
Realistically, it might not be enough to quite get it past 18% to throw a code but why imbalance the system at all? That mod is really meant for boosted applications. -JoeB