has anyone ever disconnected the vacuum line on the fuel pressure regulator??
I was screwing around at school today, im attending fanshawe college for my apprentiship, we were doing a fuel pressure lab. When you pull the vacuum line off the regulator, the fuel pressure spikes to max pressure 55psi. Now the pump puts out 55 psi at wide open throttle when there is no vacuum, but at idle the pressure drops to 42psi. With the regulator disabled, the fuel rail gets max pressure all the time. I tried it out today and the injectors still stay open the same amount of time so the cylinders get more fuel. This has no affect on top end power but it helps out a bit more on mid range acceleration.
Try it out and let me know what you think ? any thaughts or feedback??
isn't the purpose of the fuel pressure regulator to control the pressure differences needed at different rpms, at WOT the pressure is still 55 PSI im just changing the lower rpm pressure. Because the pcm still hold the injector open for 3 miliseconds if there is more pressure there will be more fuel entering the cylinders. I dont think the regulator stops the pressures form getting too high. i know its there for a reason, it would help lower pressures at idle when high pressure isnt needed
It probably will get a little more fuel, but that's not helping you out at all. You want a correct air/fuel ratio. Without introducing more air, which you're not, you're burning more fuel for no reason. The PCM controlls how much fuel the cylinders get based on the input of many sensors. If they needed more fuel, it would give them more fuel. You are essentially tricking the car into changing the air/fuel ratio and I think that could be risky.
the pcm just controls how long the injectors are open for, if there is more pressure and the injectors are open for the same amount of time then there will be more fuel in the cylinder.
you are right,, i am esentially changing the air/fuel mix, at idle the engine wants stoichiometric ratio for complete combustion but at high engine load it will ritchen the mixture for more power, im just giving it a richer mix at lower rpm, which makes harder on fuel. You wouldent want to run it like that all the time, but if you went to the track for the day it would be an easy way to pick up some accel on takeoff , because the injectors get more pressure all the time, if you combined this will a fuel pump rewire, and voltage booster you could get a little more fuel pressure??
what risks do you think there would be running a rich mixture all the time?
If you're feeling gains from that, its all in your head.
But its not my car, so do what you want. But don't recommend this to anyone please. Its really a useless mod. Your FPR is not restricting the flow of gas, you will get gas when you need it, that's how it operates.
Besides, the PCM richens up the fuel mixture under WOT to prevent detonation, not to give you more power.
Your IFR will be all kinds of Eff'd with a higher fuel pressure, which means you will run rich. The PCM can control that while in closed loop, but when it goes into open loop at WOT it's going to run stupid rich.
Leaner AFR = more power BTW. (specifically 14.7 AFR)
At WOT the fuel pump puts out 55PSI anyway, so its not getting any more fuel at WOT than it is with the regulator on, the engine gets more fuel at low rpm with the regulator disconnected because normally the regulator gets vacuum and lowers pressure
at WOT don't you want a richer mixture??
the only thing a lean burn is good for is fuel mileage, thats why all the new economy cars run an air fuel ratio of like 40:1
it seems like i pissed u off talking about this, im sorry if i did because that wasn't my intention, just trying to crate discussion about something that intrigued me, thanks for all the feedback and suggestions!
put a fuel pressure guage on the rail at idle, the guage reads about 42 psi. Crack the throttle wide open for a second, the pressure spikes to 55 psi then drops down, try it your self. then disconnect the vaccum line off the FPR the pressure jumps to 55 PSI and stays there
Injector pulse width is controlled by the PCM depending on engine load, if the knock sensor senses detonatin or pre-ignition it either advances or retards the timming to counter act, it doesnt adjust injector pulse width
to prevent detonation you would retard the timming, not richen the mixture
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum