Ecoboom related maybe?

[RedSled]

I noticed on COBB's website in the FORD Mustang ecoboost BLOG they found a problem with fuel pressure in ford's matrix software dropping under load around 3000 rpm to about almost half what it should have been, anyway I was wondering if that could cause LSPI and maybe ecoboom or be related.


I didn't see this when I searched the forums.

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[RedSled]

Cobb found this just a few months ago and has revised updated software to load onto the access port if you do a update.

The red line is the update, and the blue line is ford's original.

 

[ElAviator72]

I wonder if this LPFS related...Ford's PCM isn't smart enough to throw a code when the LPFS fails (and does so by reporting the highest pressure the sensor can at all moments, causing the stock tune to run too lean...).

 

[Bull Run]

I wonder if this LPFS related...Ford's PCM isn't smart enough to throw a code when the LPFS fails (and does so by reporting the highest pressure the sensor can at all moments, causing the stock tune to run too lean...).

Wouldn't be surprised. Just like the evap purge valve, some folks get CEL for bad LPFS, some don't.

 

[RedSled]

So is the fuel pressure drop to 1600 psi to much at 3500 rpm causing a lean condition AFR wise.

 

[RedSled]

I guess what I'm wondering is how much this played a role in blown engines.

 

[TorqueMan]

I wonder if this LPFS related...Ford's PCM isn't smart enough to throw a code when the LPFS fails (and does so by reporting the highest pressure the sensor can at all moments, causing the stock tune to run too lean...).

I'm not following this. The LPFS many are concerned with is a low-pressure fuel sensor. This graph is depicting high-pressure fuel. What would the LPFS have to do with this?

 

[Edkiefer]

I'm not following this. The LPFS many are concerned with is a low-pressure fuel sensor. This graph is depicting high-pressure fuel. What would the LPFS have to do with this?

I am not saying this is an issue but most pumps are better at pushing then sucking, so "if" the low-pressure pump was not able to flow enough to keep up with the HP one, that might be an issue.

Seems odd though that it would take so long to show up (3yrs).
That said, I guess it didn't affect AFR or it would have been found earlier.

 

[ElAviator72]

I'm not following this. The LPFS many are concerned with is a low-pressure fuel sensor. This graph is depicting high-pressure fuel. What would the LPFS have to do with this?

Well, considering that the High Pressure Fuel System gets its fuel from the low pressure rail...an inadequate amount of fuel in the low pressure rail would lead to an inadequate amount of fuel in the high pressure rail. The HPFP has to get its fuel from somewhere...

 

[TorqueMan]

Well, considering that the High Pressure Fuel System gets its fuel from the low pressure rail...an inadequate amount of fuel in the low pressure rail would lead to an inadequate amount of fuel in the high pressure rail. The HPFP has to get its fuel from somewhere...

I thought it was a sensor issue, not actual low fuel pressure. Is that incorrect? Assuming actual fuel pressure is good, how would a low pressure indication on the low side result in low pressure on the high side? As far as I know the ECU does not manipulate fuel pressure, it's supposed to be held at a constant value by a pressure regulator.

 

[Edkiefer]

I thought it was a sensor issue, not actual low fuel pressure. Is that incorrect? Assuming actual fuel pressure is good, how would a low pressure indication on the low side result in low pressure on the high side? As far as I know the ECU does not manipulate fuel pressure, it's supposed to be held at a constant value by a pressure regulator.

The HPFP is electronic too, there a command value the ECU gives and the pump tries to maintain, follow.
Check this aftermarket pump diagram as an example
https://www.livernoismotorsports.com/product/LPP501115

Also as I mentioned if you have a secondary pump way upstream (engine compartment) and your low pressure cannot handle the flow to keep up with the HP it can give issues.
I am not saying this has anything to do with OP, I don't know.

 

[TorqueMan]

The HPFP is electronic too, there a command value the ECU gives and the pump tries to maintain, follow.
Check this aftermarket pump diagram as an example
https://www.livernoismotorsports.com/product/LPP501115

I couldn't find a diagram at that link.

I found this at Motor.com:

https://www.motor.com/magazine-summary/dissecting-fords-ecoboost-engine/

The low-pressure pump is primed by the activation of the interior lamp circuit. So when you open the door, the low-pressure pump turns on for a couple of seconds to establish fuel pressure. When the PCM receives an engine start signal, it sends a 65V boost to the
fuel injectors to give them a kick start, then modulates voltage as needed. Since the high-pressure pump is mechanical, it starts working as soon as the engine starts turning.

A steel line supplies fuel to the fuel
rail from the high-pressure pump. While there’s no service port in the high-pressure side of the fuel system, some models do supply a service port on the low-pressure side. The best way to determine fuel pressures is by monitoring parameters for the fuel pressure sensor, which is located on the low-pressure side, and the fuel rail pressure (FRP) sensor, which is mounted on the high-pressure side. High pressure is controlled by a fuel volume regulator, which is pulse-modulated by the PCM, mounted on the high-pressure pump.

Both the low-pressure and high-pressure sides of the fuel system work together, and each will react to the other in case of a malfunction. We serviced a 1.6L Escape with a loss of power through the entire range, from tip-in to top speed. It ran like it was going uphill against a head wind. First thing I noticed was that low fuel pressure was about 10 psi above specification. Then I discovered that this was because high fuel pressure was running drastically below specification. The PCM was boosting low pressure in an attempt to compensate for the decreased high pressure. So when monitoring fuel pressures, be aware that an out-of-spec value on one side could be due to a fault on the other side.

So it appears the PCM will boost the low-pressure side to compensate for low-pressure on the high side, but I don't know if the PCM will cut high pressure to compensate for a high-pressure indication on the low side. That still wouldn't make sense to me since I believe the PCM controls mixture by modulating timing/duration of the fuel injector operation. The only way that would work is if fuel pressure on the high-pressure rail is held constant.

 

[Edkiefer]

In my link, it was just a graph showing the command value rate and the HPP value of the stock vers there HPFP. To see it click the product info tab.
I have nothing to do with them, there were also posts in this forum showing it but I didn't find them easily.
I guess there a lock-up table for low and high pressure and ECU will vary and try to compensate where it can.
But under full load, the HPFP does seem to have problems keeping up with modified engines.

All fuel injectors (electronic) use duty cycle, PWM for flow control and they run off 12v signal either from external or internal ballast resistor, I don't think DI changes this, that comment about added voltage sounds strange to me (65v?).
I don't have a lot of experience working on DI's but do on port injection.

Edit: I should have read your link though, I glazed over most of it and I"think" the 65"V" should have been 65lb as that was stated a starting Lb for fuel pressure.

""In a GTDI engine, fuel is delivered to the engine compartment by a low-pressure fuel pump, using a returnless fuel system. Fuel then passes through a mechanically actuated high-pressure fuel pump mounted on top of the cylinder head and driven by a four-sided camshaft lobe. The fuel travels through a stainless-steel fuel rail at pressures between 65 and 2150 psi, depending on demand, then to the fuel injectors, which inject fuel directly into the combustion chambers.""

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