Quote from: AJP turbo on December 03, 2018, 10:25:46 PM
Yes all that is well understood.....I think it's more accurate to say lower pump pressure CAN cause problems rather than DOES as you say.
I agree On not spreading bad info.....various levels of throttle control can be used to control how quickly the throttle steps in and in colder climates that can be a tool to help fuel pressure recover faster or not drop at all...but not even that can help fuel pressure if irresponsible boost levels are being used
OK, not sure where we can agree on this. Firstly, dropping fuel pressure absolutely causes issues. Ideal situations maintain commanded pressure +/- 5% or so. Messing with PID gains to try to bandaid this still leaves a large potential for stuff to go sideways since it's completely reactive to the pressure falling. Pressure drop is absolutely a bad, bad thing on the fuel system, something we will cover more as we continue. Also, most of these functions impact some other aspect of the calibration behind the scenes. Often, calculations for effective combustion pressure limits and other gains get impacted by changing these items. Basically, changing 1 thing in an EcoBoost never impacts only that 1 thing.
Quote from: AJP turbo on December 03, 2018, 10:25:46 PM
I will look at the table when I get home but look at the VE table for the high pressure pump...when pressure is lower the pump is operating more efficiently...it's just like the turbos....can they run 20 psi sure are they happier at 13 sure....I'm not saying that 1200 psi fuel pressure is ideal but the stock pump does better there....and just because fuel pressure drops that does not mean air fuels will rise...injector pulsewidth will rise though this is all assuming you are not out of injector...but stock turbos keep you in the safe zone generally...but this is where data logs are invaluable
This is very misleading. Every fuel pump on the planet operates more efficiently with less pressure. Pressure, whether Boost, or fuel, is a measure of restriction. The higher the pressure, the more volume is being forced through, and harder said "pump" has to work for similar increases. Injector pulsewidth can't overcome cylinder pressure. Only fuel pressure can do that. Telling people it's not "ideal, but it runs better there" in terms of the pump is beyond playing with fire. It shows a lack of understanding for the full range of how GDI actually needs to operate. remember, the injector is what delivers the fuel. If the pump flows more, and the injector flows less at the reduced pressure, which one is actually putting the fuel into the cylinder?
Turbos have this same phenomenon for the same reason. Pressure is a measure of restriction. So while all of this might seem like a good "reason" it's ok to run lower pressure, it's not. It's simply how things work. that doesn't mean you should be ok with drops in fuel pressure.
Other damage can happen to these engines other than just running lean. Misfires can cause severe damage to other parts/pieces (especially cats, and turbos). And often, we see failed injectors because of them not firing properly.
Quote from: AJP turbo on December 03, 2018, 10:25:46 PM
Can the HPFP run 2900 psi sure but according to the table it's happier being lower
as mentioned above, that's how every fuel pump works, the pumps happiness is trivial since it is a supporting role only for ensuring proper fuel flow. Pressure is what's needed first and foremost, flow is secondary. Since maintaining pressure can only be done by maintaining flow, your argument is counter-intuitive.
Quote from: AJP turbo on December 03, 2018, 10:25:46 PM
The VE is not the same however for a different pump
I haven't see a direct link of 1500 psi for instance inducing knock...sometimes you may see a spike there and it may be from something else...ive seen knock sensors adding spark at 1500 psi and during boost spikes also
I just can't and won't say that a pressure dip is going to cause eminent failure
Knock, misfires, inadequate fuel delivery, and reduction in power are just some of the more important things that can happen from drops in pressure. Everything you are talking about happens to be reactive items. The knock adder can add timing, until the knock sensor detects knock of course. And this always has a delay in it. Basically just because it's adding timing doesn't mean it's not going to knock. Additionally, what's the refresh rate? I guarantee you that the log is missing an event here or there.
If pressure drops enough it won't even fire the injector because cylinder pressure exceeds rail pressure. You have to remember that, just like Boost pressure on a PFI car ,cylinder pressure directly impacts fuel flow into the cylinder. so 1100psi of cylinder pressure combined with 1500 psi or fail pressure is only 400psi of effective pressure on the injector.
Quote from: AJP turbo on December 03, 2018, 10:25:46 PM
At what point is pressure adequate? If 2100 psi is good is 3000 better then we are all running too low...
All the focus on the pump too....the injectors are basically pegged and if you aren't running insufficient fuel flow ,that also can be logged ,it's probably right at that point so everyone may already be on the edge anyway...every one wants a warm and fuzzy feeling about their cars because someone like me says they are ok or a company like livernois says they are safe but that's why I hate magic number values that people throw on cars...but at the end of the day we are all hot rodding these things
this depends on the specific needs. We have EcoBoost vehicles we command and achieve over 3000 psi with. Certain builds respond better to certain pressures, but some need that much pressure. Increasing pressure automatically increases the usable range of the injector. While doubling the pressure doesn't double flow, it does substantially increase the flow rate of the injector, extending it's capabilities.
The difference as far as people asking what is, or isn't safe it we've got nearly 10 years and 30k+ EcoBoost cars/trucks we've done and had nary an issue with. We can assure people, it's not from disabling safety logic, or dumbing it down. It's been by playing by the rules, understanding how every calibration item plays it's role, and knowing why all these safety limits exist, and how the calibration truly impacts the entire engine as a whole.
in summary, pressure drop is always a negative, and sometimes a major issue. But it will also impact performance, durability, or both. The only way to mitigate this is by installing an upgraded pump and corresponding calibration.
And a reminder to people playing around with E30. These cars are out of fuel in 70+ degree weather on E10 and a tune. Running higher ethanol runs out sooner. Add in colder weather and the term playing with fire is not attention grabbing enough.