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Rawze · 05-17-2022, **(Subject: tuning question )**

(05-17-2022 )schISM Wrote: ...
Hey Rawze, I’ve been running my OFC table in a similar fashion as you described above with good results. It would look to someone like a rudimentary attempt with no thought to the outcome but I just stole the idea from an old N-14 cal. rich down low in the cranking region with a 1.5 throughout the rest of the table. Acceleration is strong with just a puff of smoke on upshifts.
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And also how do we monitor or determine if the torque/fuel tables need attention? If I remember correctly when I did anything with these tables it just made the engine wanna “run-on” when ya got out of the throttle.

last I checked.. that X15 WAS NOT AN N14~!!!.. They are not the same engine. They have completely different compression ratios, completely different injection processes, etc.etc.etc.. and do not have any of the same settings needed to operate them.

- Just because you get away with some things does not mean they are optimal. .. and YES.. by flattening out those settings, it heavily effects acceleration and its power curve by doing things like that. ... and btw, NO... it was not set like you described.. it was a bit worse. The entire table was set to a fixed value of 1.11 across the entire thing. Not terrible... or harmful. but certainly not quite right.

FYI: 1.5 is quite a bit on the aggressive side in lower fuelling /rpm ranges. It will cause some acceleration fuel mileage losses .. and can contribute towards shortening liner life on higher torque engines due to the extra aggression. On the bottom end, it is just like someone adding more bottom end torque.

1.5 however is not a bad place to be at all on the upper end where it is actually needed to help protect the engine from excessive internal temps on hard acceleration. -- It is all dependant on injection timing, expected boost, etc.. as well though. -- Hence, if you made it a bit more gentle on the bottom end, like say, 0.93~ish maybe slight higher if desired, and lead it up to that 1.5, which is still overall more aggressive than factory, because without EGr gas, it needs to be raised a bit (or better yet, done with a proper calculator to follow the factory curve) to keep the engine safe and the internal friction down a bit, then the performance would still be there without the added risk on the bottom end, or dulled curve. . Factory settings are a bit to lean to help reduce as much soot as possible into that DPF canister. That is a given, but they are not terrible, so correcting them is recommended.. but when they are flattened out like that, efficiency losses start to take hold. Remember... the engine is being used across the entire working range so who knows from one day to the next at what part of that table it will be operating in.. and for how long at a time. - Setting it to a fixed value may not always be harmful to the engine on its own, .. but dulling it like that is also not optimal for the guy who has to pay the fuel bill at the end of the day.

. And yes, too lean makes the truck feel weak, or too aggressive makes it smoke.haze, etc.. and waste fuel for any given rpm/torque requested where it was set too high, or can cause it to flat out smoke like mad because someone was too zealous. Non-egr, full PCCI or hcci/pcci designed ISX engines, the oxygen fuel control is in range of 0.93 to roughly about 1.6. - Anything higher is going to make it haze, smoke, and waste fuel possibly black smoke, and anything much less and it is going to be too lean, cause the engine to get "lazy" waiting for the turbo to catch up with itself all the time. and in a nut shell, making it too aggressive on the bottom end can also make it hard on the liners/cylinders just like adding bottom end torque. and making it too lean on the top end can be downright harmful. Just some things to think about.

I know this chart does not match the ISX.. it is for a different style of engine ... but a person can see the differences between a 'CDI' engine like the N14 was... a 'CDI/PCCI' engine, like the CM570, Cm870, etc... and attempted 'PCCI/HCCI' hybrid engine designs like that of the CM2350's and X15, etc.' ..

ref: http://rawze.com/forums/showthread.php?t...8#pid15548

Obviously the chart does not match the ISX at all, and what they need, but the overall view shows how vast the differences are between the different styles of combustion processes that has changed over the years.

torque fuel..
- Without a dyno./. no one should be messing with the torque fuel tables... That is how the engine actually determines how to make proper amounts of power. Also, in certain engine modes, and even in certain engine programs ... those tables are derated down to 85% of normal right from the factory. this becomes a problem if someone is trying to make 600HP. They must be corrected or the power will not match. The thing will feel a bit weak, etc .. and the person who made the program will usually start doing stupid s$it to try to make up for it like edit garbage they should not be editing. I see it all the time. - In the program I reviewed above, no one did the stupid s$it.. they just left it in the derated state... so I mentioned it as such.

- I have a proper calculator for torque fuel tables. They are nothing to play around with by guessing. It has taken me many years to get that calculator accurate for various model engines.. and YES.. it takes a lot of dyno testing/feedback, working with people, etc. to get right. That is why I made a calculator for things like this, so that its not a bunch of guess-work.
The things that were harmful in the program i mentioned above are ... the over-boosting, the charge flow table being jacked up to much higher numb ers, and the injection timing set slightly out of bounds. Combine it all and I see valves eating their way up into the head and/or eventual liner failure due to excessive fuel impingement buildup.
here is what it will look like after a few years of running the way it is set...
ref: http://rawze.com/forums/showthread.php?t...7#pid32957