[jlaudio11]

Originally Posted by radz28

Hmm... Maybe I'll just give this a shot. Are you saying I just raise fuel pressure in the DESIRED FUEL PRESSURE table around WOT, and see what happens?

Raise fuel pressure desired in the areas you need more fuel, so the higher cylinder airmass zones. This by itself will translate to more fuel per injector pulse. The computer knows this so it will lower ipw. It may solve your problem all together but if not, then go back to your fuel pressure multiplier tables and play with them. Either letting the direct injection cover the extra fuel need or the port, however you want to do it.

[radz28]

Originally Posted by Megahurtz

If you are already tanking the high side, raising rail pressure will do nothing.

Also, keep in mind that the SOI table is also linked to airmass.

I think you are overthinking it too much. Move your WOT spark rows up to the lower airmass rows. Do the same with your SOI. Lower your MAF. Adjust Torque Coefficients and/or Virtual Torque.

Leave commanded rail pressure and injector settings stock.

Thanks for more insight Jason. I had wondered about SOI, and you confirmed it. Thank you for continuing to help. I think others will find it useful, too, and that's super generous of you

Originally Posted by jlaudio11

Raise fuel pressure desired in the areas you need more fuel, so the higher cylinder airmass zones. This by itself will translate to more fuel per injector pulse. The computer knows this so it will lower ipw. It may solve your problem all together but if not, then go back to your fuel pressure multiplier tables and play with them. Either letting the direct injection cover the extra fuel need or the port, however you want to do it.

I'm almost done with part of this. I read your last couple posts again, and think I have a better idea of what you're saying now (in spite of my overthinking, lol). Hear me out...

I've tried continuing to lower DESIRED FUEL PRESSURE as low a 16mPa. I had continued to adjust [33355/33354] in this area, by increasing the multiplier to about 35% more than stock, as that was about what I was told I'd need for my combination. This last version, I dropped DESIRED to 16mPa for WOT and blended down, raised my E92 MAF to where it needed to be, and put all my PE back (.83). It SEEMS like the DI is behaving better, but IPW does start to slowly increase from the low 5s and creep to the upper 5s. Also - I had to pedal the throttle (one time) on a couple hits and as soon as I got back into it, IPWs didn't really try to recover, and dwelled in the 11s. It was still only in the 70s when I was able to get out there, so there's still cold weather to think about, too. I was pretty much tapped out at the maximum multiplier in the 16mPa cell, so I can't get much more out of it, so I'm not looking at a last ditch effort to try 15mPa, which gives me more, theoretical headroom. I think I dropped it to about a 40% multiplier, and blended into 12mPa or something. I copied that MULTIPLIER 3 to the MUTL. 2 table, so that should transition from PROFILEs okay. I think this is the last ditch effort for this version, because, in spite of what the instructor said, maybe I'm at the limit of this method.

I think I'm finally seeing a trend that maybe other have, and a couple have seemed to allude to. Under WOT, it seems like most of the time, so far (at least into the upper 60* temps, I can maintain good fuel control. BUT - if I have to pedal the THROTTLE for traction, it seems like the fueling just goes crazy and doesn't come back. I understand that lowering DESIRED FUEL PRESSURE will result in increased IPW, but I've been combatting that, effectively, with increasing [33355]. The issue is, that [33355] has a GM-hard-coded-limit factor of "2.0000" which doesn't lend to a lot of compensation. It seems to only allow up to about 28% or so, theoretically, if I'm calculating that right. So - unless I'm missing something, it would seem that, for a stock-cam-type build, this might be the end of the line. I have a couple more videos I want to re-review, but unless there's an injector characterization that would help in a WOT-type-scenario, I may be stuffed, and will have to start pulling from PE, and if that's not enough, break down into the E92 MAF, which is what all of this was trying to avoid... boo...

jl' - Your suggestion, if I understand it correctly now, will represent my last foray into this method. It looks like I'll put most of my DESIRED [17071] changes (go back to changing 20mPa and up; putting 20mPa and lower back the way I had them) back to the way I had them earlier, and try raising the DESIRED to maybe 22mPa. I've seen the instructor we watched and Ben Charles say that up to about 24mPa is just fine on these LT4 pumps, so I imagine I'd see a positive reaction to this change pretty easily. My goal had been to lower DI system demand, but it's also not like I'm running WOT all the time, so I realize I'm over reacting.

Let's see what happens...

[radz28]

Update: 11/23/23
Another little update...

With some cooler weather (bottom-60s and 102-103kPa barometer) and clean air, I'm taxing FUELING near as much as I'm going to in my area and at about 75% pump-E'. I've still been fighting my fight, and have conceded some losses I didn't want to here and there, but more importantly, I think I understand why, and if I wanted to, could choose to fix that later, if I want to. I'll cover a little of what I think I understand and what I'm seeing.

I'm starting to blend a little of the existing calibration trend for adding PORT INJECTION to our DIRECT INJECTION architecture. With the 85mm upper, I'm seeing some higher CYLINDER AIRMASS and MAF FREQUENCIES than I was last year (90mm upper) at this time, and similar conditions. Duh. Other than going higher in the MAF range, it didn't seem to be effected too notably, and I know some of that's covered by the REFLEX, but the compensation hasn't changed too much since September, when I was running in 30-40* higher ambient temps'.

I've been running, probably, about the maximum safe pressure the OEM LT4 HPFP will run at. I went back to my older INJECTOR PROFILE MULTIPLIER [33355] table settings, wherein I commanded the maximum factor GM allows (I did confirm that HPTuners cannot increase this more as it is a GM hard-limit). From 20mPa of DESIRED RAIL PRESSURE [17071] to the maximum, I am commanding "2.0000", and from 20mPa down to about 14mPa, I am blending to OEM values. I also copied this MULTIPLIER 3 TABLE to MULTIPIER 2 [33354] so CLOSED LOOP (CL) will behave, and be smooth. I have also commanded 24mPa, in the DESIRED RAIL PRESSURE [17071] table, from around .90g or so, but still need to go back to polishing this table for CL operation. I have some old files that will get this going pretty easily.

I'd been seeing RAIL PRESSURE and INJECTOR PULSEWIDTH go crazy at times, and especially if I was pedaling the throttle for WOT. I had been getting WOT PRESSURE/IPW holding well if I didn't pedal, but PRESSURE would drop after getting back into the PEDAL and would only start to creep-back into okay a little. Raising DESIRED RAIL PRESSURE seemed to enable more consistency than lowering RAIL PRESSURE. So - while I had tried to bring COMMANDED RAIL PRESSURE down earlier, I feel more confident that HIGHER PRESSURE (as suggested) is the better bet. If I could stay in the PEDAL and not let-off and get back into it, it seem okay. IPWs were a pretty consistent 5.0-5.2ms - right on the edge. Going back to E92 MAF - I haven't dropped that at the top of the curve - it's still about where it was a year ago. I had, in fact, added a little fuel to that curve, now, just because it was right at, about, a 0% error, so I wanted to pad that a little. I did have to increase above about 9900Hz (where I was about topped out last year) because my new 85mm upper is getting me past 10,100Hz, but that's about all I added (about 5%).

Where I am starting to concede is in the mid'-MAF-range. I introduce the REFELX around 5500Hz - just trickling it in. It's nearly imperceptible when it comes in like this, and it starts to work around 5800Hz. I'd been seeing RAIL PRESSURE/IPW issues, when pedaling, around 7000-9000Hz, so I have started pulling E92 fueling from about 6000Hz, to about the mid-8000Hz-area, and blended into the existing E92 MAF curve. I'm already a little fat in this area on the REFLEX anyways, so I'll let the REFLEX CL correct and I'll massage those corrections into either E92 or REFLEX curves, depending on IPW (as - again - already pointed out). If I need to, I'll rape the E92 MAF at the top-end, but I don't think I'll need to, too much. I've pulled about all of the POWER ENRICHMENT (PE) out of the E92, and am, pretty much leaving ALL of the PE FUELING to the REFLEX. As stated earlier, I've already moved my VIRTUAL TORQUE tables around/higher, so I believe I have that covered, for the lower TORQUE the ECM might calculate for almost no PE FUELING, so hopefully that works out as it's thought to. My reported TORQUE doesn't seem to be low anyways, and I don't see hardly any notable slip from the tranny or converter in the logs. I'll be watching in the mid'-MAF-range more, having pulled FUELING from the E92 MAF, but it should be high enough the way it is, I believe.

So - there is the latest information I have. I have several more drives since the last update, and I think I'm limited by my stock cam, for this method. In talking with the trainer, he doesn't have problems the way I'm having. To reiterate: I have reasons why I'm using the combination I am, otherwise, I'm pretty confident this method could work for anyone else with a FUEL LOBE and supporting fueling mods'. I can't validate that, so I can't offer much more reassurance than what I am directly experiencing. It DOES seem to be effective though. As I had been told from the beginning, though - my combination is simple enough such that the typical method would work just fine, and I do believe that. I came this far, though, I figured I'd follow it through as far as it would take me. And - I know I can switch over to the known method very easily. BUT - for now - back to a little more driving to finally validate this method, at least as far as I can with my combination, and for my specific reasons. Traction on the street, even with MT SSs, is if'y much cooler than this, so, practically, it might not matter to try to tune for too much cooler weather since I won't have traction anyways, lol... My OCD will argue that as valid, though, I'm sure...

I want to, also, take more time to THANK the guys out there than have been very helpful, even if I seem thick-headed. In no particular order, I want to thank: toohighpsi, laynlo15, Joshinator, jlaudio11, KingLT1, and Megahurtz. You guys have taken more time than you had to so I could continue pushing my boundaries and knowledge, and even if I am not completely successful - you helped me burn a lot more gas in my dream car, and it's been stupid fun. Thank you, gentlemen.

Another update after some more trials and validation...

[Megahurtz]

You should command stock rail pressures but you can tell the low side to start hitting max sooner in the RPM range. You want the DI injectors to maintain ~4.8-5.2ms at stock rail pressures, on E80 in cold weather so that the rail pressure won't start dropping.

Then the Port System should take up the remaining slack. Adjustment of the torque model may be necessary but there is no reason the DI side should be having any fueling issues. I don't necessarily follow the 2HPSI MAF curve spreadsheet, but thats me. I tune it more like I would tune a meth car.

[Joshinator99]

Originally Posted by radz28

Update: 11/23/23
I want to, also, take more time to THANK the guys out there than have been very helpful, even if I seem thick-headed. In no particular order, I want to thank: toohighpsi, laynlo15, Joshinator, jlaudio11, KingLT1, and Megahurtz. You guys have taken more time than you had to so I could continue pushing my boundaries and knowledge, and even if I am not completely successful - you helped me burn a lot more gas in my dream car, and it's been stupid fun. Thank you, gentlemen.

Happy to be part of your hot rodding journey my man!

[Joshinator99]

Originally Posted by Megahurtz

You should command stock rail pressures but you can tell the low side to start hitting max sooner in the RPM range. You want the DI injectors to maintain ~4.8-5.2ms at stock rail pressures, on E80 in cold weather so that the rail pressure won't start dropping.

Then the Port System should take up the remaining slack. Adjustment of the torque model may be necessary but there is no reason the DI side should be having any fueling issues. I don't necessarily follow the 2HPSI MAF curve spreadsheet, but thats me. I tune it more like I would tune a meth car.

Agreed 100%. You want DI fueling to do as much as it possibly can, but totally within the IPW, low & high side fuel pressures, and SOI/EOI limits. PI is literally just for anything the DI can’t do safely. The nanosecond the DI doesn’t look perfect, just shuffle a bit more load onto the PI.

[KingLT1]

Originally Posted by Megahurtz

You should command stock rail pressures but you can tell the low side to start hitting max sooner in the RPM range. You want the DI injectors to maintain ~4.8-5.2ms at stock rail pressures, on E80 in cold weather so that the rail pressure won't start dropping.

Then the Port System should take up the remaining slack. Adjustment of the torque model may be necessary but there is no reason the DI side should be having any fueling issues. I don't necessarily follow the 2HPSI MAF curve spreadsheet, but thats me. I tune it more like I would tune a meth car.

[radz28]

Is there a reason that I shouldn't go with raised RAIL PRESSURE? I've seen a couple training videos suggesting such, and know of a few people on HPTuners that do (I've gone as high as they say they comfortably set them to, at 24mPa on a stock LT4 pump), so I'm only asking out of curiosity. What is it I'm missing? Also - any recommendations on LPFP settings, too?

[Joshinator99]

Originally Posted by radz28

Is there a reason that I shouldn't go with raised RAIL PRESSURE? I've seen a couple training videos suggesting such, and know of a few people on HPTuners that do (I've gone as high as they say they comfortably set them to, at 24mPa on a stock LT4 pump), so I'm only asking out of curiosity. What is it I'm missing? Also - any recommendations on LPFP settings, too?

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.

[Megahurtz]

Originally Posted by radz28

Is there a reason that I shouldn't go with raised RAIL PRESSURE? I've seen a couple training videos suggesting such, and know of a few people on HPTuners that do (I've gone as high as they say they comfortably set them to, at 24mPa on a stock LT4 pump), so I'm only asking out of curiosity. What is it I'm missing? Also - any recommendations on LPFP settings, too?

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.

[radz28]

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.

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.

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...

[radz28]

I, still, have to try out the current toon, but I have been pouring over posts related to FUEL PRESSURE, IPW, and all the stuff I believe is related to what I'm trying to test. Something (maybe unrelated or not important) just hit me, as (if I ASSume injecting before TDC doesn't matter - again - still researching and NOT saying it doesn't - just making an assumption to move my point forward) I'm really having the biggest trouble when I "PEDAL" the THROTTLE. It seems, for now, at 24MPa RAIL PRESSURE DESIRED, that at a WOT hit from about 2000 RPMs (4th GEAR ~ 35 MPH), RAIL PRESSURE holds right at 24MPa, and just seems to start to trail-off at redline (6500 - plus-23MPa). IPWs are holding the entire hit at about 4.8ms, so that seems okay, too. I'm guessing I could stand to bring DESIRED RAIL PRESSURE back down, toward 20MPa (OEM pressure), and might try 21MPa this time. But - everything is looking "OK" at WOT, and NOT "PEDALING"... Which leaves contending with the "PEDALING"-part...

I pulled some fueling from the middle of the E92 MAF curve (~5500-8000Hz), because I was running a little fat anyways, and then took a little more, just to relieve the strain on the DI. I have the E92 MAF blending back into full fueling around 3/4 of the top end (~9000Hz and up). I'm hoping this might be enough to aid in reducing the load on the DI when it tries to recover and building RAIL PRESSURE back up enough to control IPW. But - I realized something else that MIGHT be contributing to why I've been experiencing these pressure undulations...

I haven't been playing with the DESIRE RAIL PRESSURE [17071] table since installing the upper. Until the upper, I had gotten it pretty close to where my STFT/LTFT-corrections were not much more than around 10% RICH. The MAF range these corrections had been made was in around the middle of the E92 MAF CURVE, and with reducing it the way I am now, this might help those CLOSED LOOP (CL) CORRECTIONS reduce further. With the corrections getting closer to ZERO, I might be able to bring [17071] pressures back up, in those CL areas. That's relevant because I'm now postulating me dropping FUEL PRESSURE in [17071] to correct for CL in these areas might be causing some of the RAIL PRESSURE fluctuations. By not commanding enough in [17071], after "PEDALING", I'm falling into part of the this DESIRED FUEL model that is commanding lower PRESSURE that is too low to recover fast enough for fueling demand, resulting in IPWs that can't come under control for the rest of the hit. I can see what seem like large swings in COMMANDED RAIL PRESSURE (that I made earlier) and think it drops too low, and that could be part of why PRESSURE just doesn't have time to recover enough. I'm thinking I need to add this to part of my last test toon...

In summary of this latest plan: I reduced the E92 MAF CURVE in the middle; I brought DESIRED RAIL PRESSURE back up (to, basically) OEM levels (in [17071]); and MIGHT take a little SOI out of the ALCOHOL table, in the same area in hopes that might take care of this "last" issue. Adding those changes together seems to, theoretically, give me a little more headroom for DI. Less MAF will be offset, some, with lower RAIL PRESSURE, but I was running a little conservative anyways, so that might be a wash, and allow me to get closer to 5.1-5.1ms for a cold day. Unless someone confirms (either way) otherwise, I still have to do more research (I've spent tens of hours over the last few years on this, but with a stock cam [and running gasoline], there wasn't much of a point, lol...) on the below bullet points. I know I'm making, at least, a couple of assumptions in my theory for this toon, but maybe some of what I need to look more at doesn't matter too much...

• Research safe limit of LT4 INJECTOR PRESSURE
• Research INJECTION STARTING BEFORE REACHING TDC

[radz28]

12/14/23 UPDATE (minor):

There's still a little homework to do, and I'm working on that, but it seems like I have a little improvement for WOT fueling.

My last hits were in 52* ambient temperatures. I'd been focusing on on-and-off-the-throttle-fueling, where I'd been struggling, and 3 out of 4 times RAIL PRESSURE held. I commanded 21MAp of rail pressure, and that's what I received. IPWs were holding well at about 5.1-5.2ms, through 5700RPMs, where I ran out of b@ll$ because of traction, but tracked right on top of some other low-50*s runs, so I'm not too worried about consistency. I'll try again to confirm, through 6500, but getting bottom 5s for IPW was good. I had played with SOI a little, and think that may have helped a bit. I was running into part of the SPARK TIMING map that I hadn't been in before, so I wasn't too comfortable staying there, which is also part of the reason I didn't stay in the throttle, but I've made adjustments to correct that now. I, still, had the one hit that RAIL PRESSURE dropped when pedaling.

The particular instance where RAIL PRESSURE didn't quite come back was where I waited about a second before getting back on the THROTTLE (this was about 4700 RPMs). That was enough time for commanded RAIL PRESSURE to fall close to IDLE, and just didn't have time to recover at WOT, or, it was just not going to recover. I raised commanded pressures above the last tune revision to see if that would help. So I'll see what happens.

Thinking back to why this situation was created, I lowered a lot of the DESIRED RAIL PRESSURES because I was trying to compensate for the fueling in CL. I can't remember trying before, but this time, I'm going to try to bring more fueling in, for these areas, with the PORT, and see if that will cover this area, and help the DI recover RAIL PRESSURE easier. In the past, I thought I would be throwing PE off with the PI in these spots, but I was probably confusing myself, so we'll see which thought process was right. So - I've lowered the E92 MAF in this range, and bumped the PI to try to compensate. Additionally - I thought I might try to bring PE (from DI and PI) in a little sooner, too, in an effort to cover this part of the RAIL PRESSURE table better. I had PE set to about 45% PEDAL until now, and dropped it to 40%, so we'll see. I didn't want to constantly be in PE, so I'll see if this helps, or not. I really, just have this small part of the curve I think I need to play with, and this will be as good as I can get.

So - it sounds like, if I wanted, I could probably command a little more RAIL PRESSURE than I am now, but don't really want to do that yet. I'm hoping that fattening up the PI MAF in this area will help the DI PRESSURE recover. If I stay in the THROTTLE, there is no issue, but this pedaling is killing it. There's probably something to be said about working this hard to get this method to work when it's this cold (and this time of year), there's hardly any traction on DRs, on the street, but my OCD won't let me give up quite yet. It's not like I street race, and the track 5-minutes away is closing, so it's not like this is going to matter much, but I just can't help myself. I just have to know. I've added a more SOI lower in the RPMs and retarded cam timing back to where I usually have it advanced to, which may have helped a little also (if I understand that relationship well enough). My SOI came down a few degrees (from 378 to about 370, in cooler conditions), so I'm wondering if that helped a bit. I'm wondering about retarding cam timing a little more from where I have it, to try that out, but we'll see...

Some more hits over the weekend if I can beat the rain and it's cool enough to tax everything...

[laynlo15]

Geez, you are going deep into this tuning. Great job