Quote:
Originally Posted by codyace
Another thing to check (being you're not rewired) is alternator output at WOT. Not sure if the ApexI unit does this or not...I know I can log it though with my Conzult.
I can see your train of thought, but to me, 62 psi from the pump is 62 psi from the pump...and shouldn't require any more fuel in the grand schme of things...what you're describing would be in the event the pump is weak, and the regulator is only persay putting 55 psi at WOT to the car...which would then make sense (higher duty cycle) as the injectors are being asked to work faster.
For what? Just put a T in your fuel line, run it up to the window under the wiper. At the other end of the line, just put a gauge in. Crude? certainly...but it's mechanical, and it works.
This has become quite the troubleshooting thread  Nice to see some civilized car discussion going on |
1) My Apex'i Turbo timer can output voltage while the car is running. Usually at idle it's around 13.6-14. Never bothered looking at it under load really, but I will check
2) What you said about injectors working harder is what I am talking about.
Let me explain this (but I COULD BE WRONG).
When the fuel pump can EASILY outflow the amount required, the FPR can maintain 1:1 pressure with boost no problem.
But what I think is happening here, if my pump is weak, is that as boost goes up and hits 19 psi, the fuel pump cannot generate enough flow to create 62 psi of back pressure at the injectors. so they only see something like 55 psi.
Remember there is no "feedback" on an FPR that tells it to close down diaphragm to achieve X psi in the rail. It just so happens to have a spring in it that when it sees Y psi of boost from the manifold, it closes the open in such a way that the fuel pressure goes up by Y psi.
This does not necessarily have to be linear 1:1, particularly if you are greatly overworking the spring or the fuel flow is not even strong enough to create that much pressure
I really feel like I am bullshitting haha but maybe not
NINJA EDIT!:
From fluid mechanics. Let's say that the FPR closes down COMPLETELY, so that all of the fuel is going directly into cylinders through the injectors.
Now, this corresponds to some fixed flow rate moving through some orifice.
There will be some pressure difference between rail and cylinder associated with this.
For fixed cylinder pressure, you can obtain pressure in the rail.
What I am saying here, is that even under full flow scenario, where ALL fuel goes into cylinders, the pressure required to do this could be way less than let's say 62 psi.
Basically, I imagine a scenario where the fuel pump is weak so the FPRs spring no longer produces 1:1 boost:FP increase.
I really do actually think this makes sense.
I would love to hear some thoughts/criticisms
3) I actually was gonna do that with the FP gauge out the window and my friends told me I was retarded.
Will probably do it now though.
4) Yes, I really enjoy this thread when it starts getting down to the details, even though I feel like I am kinda threadjacking.
Hopefully I am contributing though.