the cause of #8

[RSKtakR]

Do you have an idea how pressure works in an enclosed area such as a fuel rail? Lets make a number that the fuel rail pressure should be. We will say 40psi.
It is physically impossible to have 40psi of pressure at the injectors at the front of the rail and less pressure at the injectors at the back. Pressure is created by restriction or resistance in the path of flow.
The pressure at the front of the rail is created by the restriction of the end of the fuel rail where the fuel has nowhere to go but through an injector. Think about it.

BUT when the car is at WOT how could it be possible to maintain that 40psi through the ENTIRE fuel rail on BOTH sides? 40psi /2.. then 20/4.. ?

 

[Fallenauthority]

BUT when the car is at WOT how could it be possible to maintain that 40psi through the ENTIRE fuel rail on BOTH sides? 40psi /2.. then 20/4.. ?

Are you serious? You do know that the pump speeds up to maintain constant pressure right?
And its not 20psi/4 injectors, each injector gets 40psi fuel pressure, pressure doesnt get divided in half for each side of the rail.

 

[BAKnBLK2010]

Take some strings of regular Christmas lights. String 5 or 6 strings together. Plug them up. Take the bulb out of the 1st string and make a voltage reading with a DVM. Replace the bulb. Go to the very end of the string and take the bulb out and read the voltage.

The voltage at the end of the string will be lower than at the very 1st bulb. In Electrical terms: voltage = pressure and current = flow rate.
All of those bulbs are your injectors feeding from the common source....trust your local phycist/engineer here...

HTH

Mike

These cars are not failing at WOT so the fuel rail isn't the problem. The failures are happening at light throttle in high load situations when the computer throws more timing at the motor to compensate for the increased load. There have been many people state that they were just cruising along in slow traffic when the failure happened.

 

[Bmr4life]

These cars are not failing at WOT so the fuel rail isn't the problem. The failures are happening at light throttle in high load situations when the computer throws more timing at the motor to compensate for the increased load. There have been many people state that they were just cruising along in slow traffic when the failure happened.

I agree, that's what I've been reading also.

 

[kdanner]

You do know that the pump speeds up to maintain constant pressure right?

No it doesn't. This is not an electronic returnless system.

 

[BAKnBLK2010]

If the pressure in the rail is constantly above what the injector is calling for that is all that matters. The injector controls how much fuel is injected into the cylinder not the fuel rail pressure istself. These cars n/a are not running out of fuel under any circumstance.

 

[Fallenauthority]

Apples I would like you to meet Oranges.
You are comparing two totally different principles. We are talking fluid dynamics, you are talking electrical. So your example does not work.
And to the dude who replied to my pump comment.
I'm not familiar with whatever the new fuel system is on the coyote but I do know that there is a way to increase the flow of fuel when the demand is there, regardless of if pump speeds up or however this new system works, the ability to flow more volume to make up for increased demand is there.

Take some strings of regular Christmas lights. String 5 or 6 strings together. Plug them up. Take the bulb out of the 1st string and make a voltage reading with a DVM. Replace the bulb. Go to the very end of the string and take the bulb out and read the voltage.

The voltage at the end of the string will be lower than at the very 1st bulb. In Electrical terms: voltage = pressure and current = flow rate.
All of those bulbs are your injectors feeding from the common source....trust your local phycist/engineer here...

HTH

Mike

 

[302]

Apples I would like you to meet Oranges.
You are comparing two totally different principles. We are talking fluid dynamics, you are talking electrical. So your example does not work.
And to the dude who replied to my pump comment.
I'm not familiar with whatever the new fuel system is on the coyote but I do know that there is a way to increase the flow of fuel when the demand is there, regardless of if pump speeds up or however this new system works, the ability to flow more volume to make up for increased demand is there.

Actually the principles are the same, but different medium. Electrical current takes the same characteristics of a given fluid in a pipe.

 

[Fallenauthority]

Actually the principles are the same, but different medium. Electrical current takes the same characteristics of a given fluid in a pipe.

Except for the fact that fluid at the end will be the same pressure as the fluid at the beginning. Unlike electricity

 

[302]

Except for the fact that fluid at the end will be the same pressure as the fluid at the beginning. Unlike electricity

So you mean to tell me if I were to take a 2" pipe with liquid flowing at a given mass flow rate it will be the same at point A and at point B?

 

[white05gt]

Except for the fact that fluid at the end will be the same pressure as the fluid at the beginning. Unlike electricity

You have to have volume and flow in order to have pressure, in the case he is saying if the rails are too small, there won't be enough volume at the end in order to give you the pressure. Why do you think their are specs on both plumbing and electric for larger pipe or wire depending on distance?

 

[BAKnBLK2010]

This thread has taken a wrong turn.

 

[kdanner]

Yes, people seem to be forgetting that if there was a capacity problem with the rails, blown cars would be melting down far easier, yet they aren't.

 

[RSKtakR]

Yes, people seem to be forgetting that if there was a capacity problem with the rails, blown cars would be melting down far easier, yet they aren't.

do the blown cars have BAP's?

 

[kdanner]

do the blown cars have BAP's?

I certainly hope so. I have 2 NA cars here running on E85 with zero fuel system changes, and they aren't melting down either. There isn't a rail capacity problem.

 

[Black 5.0]

I beg your pardon you can! That fuel rail can easily have non uniform pressure across it!

Take a garden hose. Pressurize it to 40 psi and then cut holes in it the entire length. Take a pressure reading down at the very end of the hose and tell me what you see! If you want to get it back up to 40, you're gonna have to flow a shitload more water through it for that to happen at the very end.

If the flow of fuel becomes such that the fuel pressure begins to drop, those two injectors at the end will see lower pressure. If I am not mistaken, the injectors basically come on full force at WOT...

It may be fine, but I just wanted to point that design flaw out. It would be easy to check each end of the rails out with fuel pressure sensors and gauges.

If #8 is running lean, it has to be because of a lack of fuel.....the way the intake is laid out, it can't give that cylinder MORE air.

HTH

Mike

Except for the fact that you are leaving out the pressure regulator in your 'garden hose'. That's what a pressure regulator is for. To maintain equal pressure throughout the line. It is possible that the regulator may be limited in max pressure allowed. However, I believe through the testing of this engine, any pressure issue would have been resolved.

You can test pressure in the rail if there is reason to believe there is a pressure drop. I don't think a custom tune is going to cause this. The fuel pump alone generates more pressure than is seen in the fuel rail which is another reason for a regulator. If more fuel is needed, the regulator should adjust for it.

 

[RSKtakR]

I certainly hope so. I have 2 NA cars here running on E85 with zero fuel system changes, and they aren't melting down either. There isn't a rail capacity problem.

I also run E85 in my 2011 w/ no fuel system mods, and it runs like a bat outa hell... just worried about when im running an aftermarket 91oct tune really.

 

[Fallenauthority]

If there is something regulating the pressure within said pipe and the pump supplying that pipe with liquid can maintain said pressure, yes.

So you mean to tell me if I were to take a 2" pipe with liquid flowing at a given mass flow rate it will be the same at point A and at point B?

 

[Fallenauthority]

You have to have volume and flow in order to have pressure, in the case he is saying if the rails are too small, there won't be enough volume at the end in order to give you the pressure. Why do you think their are specs on both plumbing and electric for larger pipe or wire depending on distance?

I'm pretty sure ford knows how to size a fuel rail for an engines demands.

 

[white05gt]

I'm pretty sure ford knows how to size a fuel rail for an engines demands.

I didn't say that's the issue, I was explaining what was being discussed about pressure.