Quote:
Originally Posted by Joshinator99
You can, just keep in mind that is not a free lunch and not linear. A 20% increase in rail pressure does not equate to a 20% increase in injector flow. And asking the pump to produce more pressure will make it tap out volume-wise sooner (just like all pumps). You can do it, just do your usual due diligence and watch all your numbers and see if it helps.
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Thanks Josh. That makes sense, because I have not been seeing a consistent correlation along the lines you just stated. Thank you for confirming that for me.
Quote:
Originally Posted by Megahurtz
There simply isn't any reason to do so if you have port injection. There are risks with increasing rail pressure above stock values. You can cause DI injector misfires. The stock injectors seem to be OK up to 3200 PSI and some guys have run them to 3400 PSI. But the higher you go, the more risk for injector misfire which if it happens at WOT( which is when the pressure would be high) you risk hurting a cylinder. Why add the risk? Second, the higher the rail pressure the more severe the "out of fuel" drop off will be. You could go out in 70F weather and the pressure holds and all is good, then you go out in 60F weather and the demand is a little higher, but rail pressure tanks. Then the DI injectors fire deep into the compression stroke, the port injectors already fired and now you have a big chance for detonation as the charge isn't burning properly. This can also hurt the engine.
So my point is, if you have port injection, why would you even want to try to squeeze the DI system? There is no benefit to it. Only increased risks. Tune the car so that you can beat on it in the summer and then beat on it in the winter on E80 without any worry of the DI side having an issue.
You can adjust when the ECU tells the low side that it should go into high flow mode with the below tables. You will need to change both tables.
Attachment 1141387 |
Right now I'm logging almost
380* SOI and
193* EOI at
WOT (6500 RPMs) and
IPWs are
4.7-4.8ms. I'm also seeing that I'm injecting after EVC and NOT into compression. I AM NOT starting injecting after TDC, though. I had commanded 24MPa (this was the runs before your responses) and it was holding and probably
just diddling to 23MPa at 6500. I know I can't (and probably shouldn't from what you posted) command more FUEL PRESSURE from the HPFP, and, perhaps, I can lower BASE SOI but that will probably push my IPWs up a little, right? It looks like I have a little room to spare, as this was 63* ambient (as logged), but it looks like I'm pushing fuel out of the exhaust valve, probably, right? At least that's what it looks like, according to my SOI calculator...
For sheets and giggles, I thought I might try to drop HPFP down to 22MPa and see if I can get that to hold around the mid-50*s ambient. I'm just a glutton for punishment. I just wanted to say I took this as far as I could, given my limited knowledge. I do, finally, feel like I have. It must be the OEM cam, as the person who put the training on said he didn't have this kind of trouble. I'm the only ding dong that's trying to do this, with this combination, so I'm an outlier.
I've also adjusted those tables, by lowering them some, if I recall. I've messed with a couple others in the FPCM (VOLTAGE, MIN DC, BASE, and a few of the LOW-PRESSURE pump settings, too). I forgot the logic, so I'll have to go back and look at that...
So - one more test, and final attempt to see if my interpretation is correct. Thanks Josh and Jason for your continued support. None of your suggestions have fallen on deaf ears, as much as it might seem like it. I already have a file, in the architecture you've stated (multiple times
) started, so it's just me being disagreeable. I want to offer as complete a report, too, to anyone thinking about this method. I'd, still, rather explore this method if I had a cam, but that's just me, and my OCD...