Turboing my LC Accent; fueling dilema revisited
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Joined: Jul 2001
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From: parkville, md
Vehicle: 1997 accent L
Turboing my LC Accent; fueling dilema revisited
Red, Random, cheuk, and the rest, i know i'm beating a dead horse with this by now, but i have another idea on how i can get my 1.6L the fuel needed.
The idea: source the return fuel line, rail, and pump from a 2000+ accent with the 1.5L and put them on my car, add a rrfpr, replace my n/a map with a 2bar variant, and tune it.
The theory is that since the 2bar MAP sensor still sends the same 0-5v signal to the ecu, the car will just think its at higher altitude and continue to send fuel as normal (albeit at less quantities than at sea level). I then crank up the fuel pressure using the rrfpr to compensate, and possibly get larger injectors.
Sound feasible?
The idea: source the return fuel line, rail, and pump from a 2000+ accent with the 1.5L and put them on my car, add a rrfpr, replace my n/a map with a 2bar variant, and tune it.
The theory is that since the 2bar MAP sensor still sends the same 0-5v signal to the ecu, the car will just think its at higher altitude and continue to send fuel as normal (albeit at less quantities than at sea level). I then crank up the fuel pressure using the rrfpr to compensate, and possibly get larger injectors.
Sound feasible?
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Joined: May 2001
Posts: 11,851
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From: Rancho Palos Verdes, CA
Vehicle: 2008 Toyota Prius 2006 Suzuki SV650S
Just creating a "returnless" fuel system might work. As the un-needed fuel will just route back to the fuel tank.
Swaping from a 1 bar to a 2 bar map is a bad idea. The ECU will send HALF the fuel via the injectors, you would have to crank up the fuel pressure over double the stock figure to equal the same flow. (bad idea for fuel pump life!)
Simply going with a normal return style fuel pump should do the trick. The ECU should 'learn' how to adjust the injectors to compensate for a constant fuel pressure with the return line.
If you are refering to how to "trick" the ECU into adding the proper fuel, the 2 bar map sensor will STILL send the ECU half the signal.
(just a theoetical exaple)
a 1 bar map sensor sends out;
0.01V for -1 bar pressure
.5V for 0 pressure
0.995V for +1 bar pressure
a 2 bar map sensor send out
0.01V for -2 bar pressure
0.25V for -1 bar pressure
.5V for 0 pressre
0.75V for 1 bar pressure
0.995V for 2 bar pressure
So, if you use a 2 bar map sensor, your car will overfuel at low pressure and under fuel at high pressure and will only properly fuel near zero. Adjusting the fuel pressure UP, just makes low pressure fueling worse(richer), and high pressure fueling a tad better (not as lean).
If you were to try to make it work at high pressure (boost), by increasing the fuel pressure you would be making the low pressure/vacuum rich condition even worse.
A S-AFC might be able to help you at low pressure to lean it out, but in general, you are going to run damn rich at low manifold pressure/vacuum, and very lean at high Manifold pressure/boost.
It would be a better idea to keep the returnless fuel system, and simply install larger injectors and tune them down with the S-AFC, or go with a real stand alone system, and ditch the returnless fuel system.
Swaping from a 1 bar to a 2 bar map is a bad idea. The ECU will send HALF the fuel via the injectors, you would have to crank up the fuel pressure over double the stock figure to equal the same flow. (bad idea for fuel pump life!)
Simply going with a normal return style fuel pump should do the trick. The ECU should 'learn' how to adjust the injectors to compensate for a constant fuel pressure with the return line.
If you are refering to how to "trick" the ECU into adding the proper fuel, the 2 bar map sensor will STILL send the ECU half the signal.
(just a theoetical exaple)
a 1 bar map sensor sends out;
0.01V for -1 bar pressure
.5V for 0 pressure
0.995V for +1 bar pressure
a 2 bar map sensor send out
0.01V for -2 bar pressure
0.25V for -1 bar pressure
.5V for 0 pressre
0.75V for 1 bar pressure
0.995V for 2 bar pressure
So, if you use a 2 bar map sensor, your car will overfuel at low pressure and under fuel at high pressure and will only properly fuel near zero. Adjusting the fuel pressure UP, just makes low pressure fueling worse(richer), and high pressure fueling a tad better (not as lean).
If you were to try to make it work at high pressure (boost), by increasing the fuel pressure you would be making the low pressure/vacuum rich condition even worse.
A S-AFC might be able to help you at low pressure to lean it out, but in general, you are going to run damn rich at low manifold pressure/vacuum, and very lean at high Manifold pressure/boost.
It would be a better idea to keep the returnless fuel system, and simply install larger injectors and tune them down with the S-AFC, or go with a real stand alone system, and ditch the returnless fuel system.
Thread Starter
Senior Member
Joined: Jul 2001
Posts: 691
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From: parkville, md
Vehicle: 1997 accent L
<div class='quotetop'>QUOTE </div><div class='quotemain'>Random:
Just creating a "returnless" fuel system might work. As the un-needed fuel will just route back to the fuel tank...
...Simply going with a normal return style fuel pump should do the trick. The ECU should 'learn' how to adjust the injectors to compensate for a constant fuel pressure with the return line.</div>OK, i'm sorta confused now. How is the fuel going to get back to the tank in a returnless system? I thought that was the point of the returnless system...
Also, i'm 95% sure the stock fuel pump has the pressure regulator on it. If I replace it with a normal pump, how is the pressure going to be fixed? The regulator would have been removed with the OEM pump, i think... I think i better get to a junkyard and find an accent fuel pump assembly.
Just creating a "returnless" fuel system might work. As the un-needed fuel will just route back to the fuel tank...
...Simply going with a normal return style fuel pump should do the trick. The ECU should 'learn' how to adjust the injectors to compensate for a constant fuel pressure with the return line.</div>OK, i'm sorta confused now. How is the fuel going to get back to the tank in a returnless system? I thought that was the point of the returnless system...
Also, i'm 95% sure the stock fuel pump has the pressure regulator on it. If I replace it with a normal pump, how is the pressure going to be fixed? The regulator would have been removed with the OEM pump, i think... I think i better get to a junkyard and find an accent fuel pump assembly.
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Joined: May 2001
Posts: 11,851
Likes: 2
From: Rancho Palos Verdes, CA
Vehicle: 2008 Toyota Prius 2006 Suzuki SV650S
Sorry, a meant a normal "return" system.
You have to replace the pump, and get a fuel pressure regulator that is adjustable or get a stock accent unit.
You have to replace the pump, and get a fuel pressure regulator that is adjustable or get a stock accent unit.
Thread Starter
Senior Member
Joined: Jul 2001
Posts: 691
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From: parkville, md
Vehicle: 1997 accent L
Ahh, ok. Conversion to return system it is. Thats probably a better idea anyways.
I'm going to try to goto a junkyard this weekend or next and start rooting around for a dsm turbo and o2 housing (maybe downpipe too) so I'll ask about the accent fuel rail and return line while i'm there.
BTW, you wouldn't happen to know the flow rate of the stock tibby injectors, would you?
Thanks again. smile.gif
BTW, i think I'll try to go with the Split Second ARC1-002 that cheuk mentioned back on fxtreme for the fuel computer...
I'm going to try to goto a junkyard this weekend or next and start rooting around for a dsm turbo and o2 housing (maybe downpipe too) so I'll ask about the accent fuel rail and return line while i'm there.
BTW, you wouldn't happen to know the flow rate of the stock tibby injectors, would you?
Thanks again. smile.gif
BTW, i think I'll try to go with the Split Second ARC1-002 that cheuk mentioned back on fxtreme for the fuel computer...
