Phil48315

Look good ?

KennyCJR

iTrader: (3)

Perfect! Thank you, sir. 🍻🍻

SALEEN961

iTrader: (1)

At this point I'm still an amateur in training, but I'd be happy to help anyone learning to tune their 3.5EB F150 by sharing the things that I have learned so far. In the past 5 months I've gone through about 140 different tune revisions as I have been trying different tuning approaches and working to better understand certain issues. With a 13th gen F150, the process should be a bit easier as courses like the one offered by The Tuning School directly apply to those F150s.

Finding information on what certain limit sources mean and how the PCM determines you are hitting those limits seems to be one of the biggest challenges if you want more than just a mild tune. Without a good understanding of what all the limits mean and how the PCM determines a limit is being hit, it's difficult to make informed decisions and I often feel like I'm playing guess and check. I'm really struggling to find info on the preignition FMEM limit for my 2021 3.5EB, and based on how little information I'm finding online I have to wonder if this is a commonly encountered limit for the 13th gen F150s or if it's more of a 14th gen issue.

engineermike

@SALEEN961 check table 7711. It’s fmem load limit for LS preignition.

SALEEN961

iTrader: (1)

@engineermike
I thought that 7711 only set the load limit after the pre-ignition FMEM limit had been triggered and wasn't used as part of why it is triggered. I had been looking at the pre-ignition thresholds listed under spark>knock sensors at 18690-18695 that my stock file has set to 3.5 in every cell compared to 2.25 in the 13th gen 3.5EB stock files I've seen. The description for those parameters is "pre-ignition threshold for cylinder X: This defines the detection threshold for pre-ignition".

It sounds like it is saying that any knock retard over that value is interpreted as pre-ignition, but a value of 2.25 or 3.5 seems too low for that to be true, especially since I routinely saw more than 4° of sustained KR under certain conditions on my stock file without hitting this limit. The very last time I hit the pre-ignition FMEM limit, I only saw 1.6° of KR when it occurred in 3rd gear and the highest KR value recorded anywhere near that point was 2.9 of KR in 1st gear. In the proceeding WOT pull with the same file I saw -2.9° to -0.4° of KR during the pull with the same spark tables so I don't think pulling more timing is necessarily the answer here, but KR always seems higher than what I normally see when I hit the pre-ignition limit.

engineermike

@SALEEN961 is this showing up as a spark source or load/lspi/popcorn or some other throttle limit?

SALEEN961

iTrader: (1)

@engineermike The two recent times that I have been able to catch it on a datalog, I had the following show up in my sources right as my CEL started flashing and I got a misfire code from the injector cut. The misfire code is usually P0303, but I have also seen P0306 and P0305.

Torque Max Source: Non-Enriched Load Limit
Torque Max Protection Source: Preignition FMEM
Fuel Source: Injector Cut
Fuel Source (Torque Reduction): Hard Cut

engineermike

My understanding is that the preignition detection is the same as knock detection, but the “listening window” is before spark vs knock being after spark. What I don’t understand is how spark retard would help with preignition. I’ve seen bits here and there in the tune where it could potentially cut load or add fuel to address preignition.

That said, I’m not sure yours has anything to do with preignition. Something is definitely happening with the fuel system but the preignition fmem could be an effect not a cause. I’d start logging all the torque ratios and see if any clues are there. It’s odd that it bypasses spark torque ratio and skips to fuel cut. That may actually be a clue because ecm33458 tells you which torque sources aren’t allowed to use spark TR.

SALEEN961

iTrader: (1)

This is the best explanation that I have seen and that makes much more sense to me.

I was planning to fill up with Sunoco 260GT 100oct fuel tonight to see if I still have issues with higher octane fuel. My hope is that this could be useful in determining whether the preigntion FMEM limit is the primary cause of my issue or just a symptom of something else. I'll start logging all the torque ratios as you suggested and do some more reading on how they are used.

engineermike

That’s probably a good plan but preignition doesn’t typically occur at high rpm.