engineermike

Yea, what I've found is that it's not that simple. The torque tables are assuming no parasitic losses, no pumping losses, MBT timing, stoichiometric A/F ratio, etc. So, it's possible that in those higher torque mapped points, the turbocharger drive pressure or pumping losses are worse so the net power is lower. It's also possible that borderline timing is higher and/or MBT is lower in the lower-torque mapped points, so the timing difference winds up netting more power.

For example, the torque calculation shows that max torque is obtained at lambda of around .85 but the PE table calls for as low as .70 in the 3.5 EB. But if you look at lambda vs Borderline timing and timing vs torque ratio, it becomes apparent that the rich lambda of .7 allows more spark timing and the power difference that timing makes is more than the loss in torque due to just rich lambda.

engineermike

If you have one LSPI weight then I think it's pretty clear how it works. The output from the blend table corresponds to the LSPI table used, -1 = low eff, 0 = nominal eff, and +1 = high eff. So when your octane lspi blend table topping out at 0.6 output appears to limit how much it weights the high effectiveness table. However, in your cal, you have three blend tables populated (octane, lambda, and preignition). I don't know if that was the factory settings or something you did. But I'm not completely sure how it combines the 3 blend factors to determine how the 3 LSPI load limit tables are weighted. I don't think it's multiplicative because that would turn the entire output negative with only one factor being slightly negative. It might be additive, which would explain how you could achieve 1.0 weight of the high eff table with factors of only .6 and .67 going into it.

SALEEN961

iTrader: (1)

The octane, lambda, and preignition blending tables are all stock. The idea that the blend tables are additive does make sense assuming they are using the Knock Octane Modifier value reported in VCM scanner where +1 is good and not the Octane Adjust Ratio value reported in all my other tools where -1 is good. I'm not sure if these are completely different values or if the OAR is just the inverse of the KOM. I only mention that because VCM scanner, Forscan, and my scantool are all limited in which PIDs they can log, so it's hard to get the full picture using just one tool with one set of terminology. My main reason for not touching these values up to this point was my lack of understanding how the PCM is using these values.

Things are rarely ever as simple as they initially appear and I don't doubt you at all. When I lasted checked a few months back, I couldn't log turbocharger drive pressure with VCM scanner, but I can log it with my scan tool. I was considering staying in MP18 at high RPMs and not using MP12 past 5300RPM because in the engine torque tables, MP18 makes essentially the same HP, but in my logs MP18 also appears to tolerate more ignition timing than MP12. It was while I was looking into this that I noticed other MPs that listed making more high RPM HP than either MP18 or MP12. I'll probably wind up finding that the loss of ignition timing after going to MP12 is coincidental and not a direct result of being in MP12, but it's something to investigate when I get to my boost target.

engineermike

@SALEEN961 you should try pcmtec. It probably has at least 10,000 logging parameters. The biggest challenge is finding the one you’re looking for. You can actually log the input and output of every table in the pcm.

KennyCJR

iTrader: (3)

I haven’t played with any of the mapped points yet, other than log which points are being used at WOT. How is your scanner setup to see how much horse power each mapped point is making?

SALEEN961

iTrader: (1)

@engineermike Thank you for the detailed feedback, this completely fixed my issue.

I rescaled the IPC torque max, IPC torque min, IPC MAP max, and IPC spark max tables found in the Torque Model>Monitoring tab up to 2.5 (changing the scale on any of these tables rescales them all). I also rescaled the Engine Torque 0 - Engine Torque 18 tables found in the Torque Model>General tab up to 2.5, I just measured the difference in the torque values between 2.2 load and 1.9 load, added that to the 2.2 load values and called that my 2.5 load. Obviously this was a pretty crude adjustment, but I figured it would close enough to work as a proof of concept.

Making these changes allowed me to exceed 2.2 load, I currently have my LSPI HI table capped at 2.3, and my truck hits 2.3 load without issue. I'm currently hitting 20psi of boost in 27°F weather and after a 1/4 mile pull my manifold charge temp is 86°F. I'm not sure how much power I should expect to be making at 2.3 load, but my turbocharger airflow peaks at just over 63lb/min and launching the truck is triggering the pre-collision assist warning light. At this point, I feel like I'm getting very close to the limit of what the locally available 93oct can handle. There is a local station with a 100oct pump, but they're proud of it and I don't need to spend that much of fuel.

SALEEN961

iTrader: (1)

I have been having a very intermittent issue with hitting the Preignition FMEM Limit / Injector Cut / Hard Cut on my 2021 F150 3.5 Ecoboost for awhile now, and I'm unsure on how I should proceed with this particular issue as it isn't covered in the courses from The Tuning School or Elite Tuned.

The issue can occur several times in the same day, but I can also go months and dozens of WOT pulls without it occurring. I attached a log showing a normal WOT pull in 4th gear and a WOT pull in 4th/5th where the issue occurred. What normally happens is during a WOT pull I will feel that the engine is slightly down on power at high RPMs, presumably due to the high KR seen when this occurs, I'll get a flashing check engine light, and when I pull the code it is usually P0303, but I have also seen P0305 and P0306.

My truck only has 15K on it, and the spark plugs were replaced with 1 heat range colder NGK Ruthenium 95605 gapped at 0.024", the issue was also present with a different set of the same NGK plugs gapped at 0.028". I only run 93oct fuel and I don't believe this be a fuel quality issue. I think I first started experiencing this issue at 1.9 air load, but I could be mistaken about that, it has definitely been happening at 2.1 load and higher.

Any advice or recommended reading on how I should address this issue would be greatly appreciated, searching the HP tuners forum for preignition FMEM limit isn't giving me any results.