Injector Table in relation to Cam Table

[MikeM173]

I want to first apologize for the photo because I am not an artist, and I have never uploaded a pic to a website before really so I'm not sure if this will come out big enough and clear enough. Now moving on.

[cobaltssoverbooster]

a great way to double check injection window problems is to log kr on the same axis requirements that the window adjustments are based off of. if you get random kr more frequently there make an injector window shift and 70% of the time it goes away. the other times its fuel or spark related and you will have to explore your table combinations to solve it correctly.

[08VRSS]

Maybe i am reading and interpreting this incorrectly. I was reading overbooster's thread on bring back injector timing and it seemed that he was saying that advancing the window, starting the spray earlier was more beneficial; ie raising the values slightly. What I'm getting from this post is opposite? Meaning starting the injection later will make a better, narrow window? I'm not having any issues so far like a pressure drop but haven't really been able to max my setup out in traffic here to over ~5800 rpms unfortunately. I'm seeing up to 7.3 ms though at 5300 rpms. E47 and .89 lambda 25-26 psi, timing 23*. So what I'm asking, to make sure i won't get any injection window misfires should I be increasing or lowering the number in the hom low table? Any other editing required to the other comp or int fuel tables? My cam tables are borrowed from BYT when he did the E85 testing and my injector angle tables are stock. Or should i be more worried about running out of fuel flow?

[08VRSS]

This may be a stupid question, but if you start the spray 5* after the intake valve has opened, why would the spray terminate sooner than if you started the spray 5* before the valve opens? To me it seems that if you started the spray sooner, it would end sooner, and if you started the spray later it would end later or closer to ignition. I see how to adjust the starting angle, and what affects it would have on altered cam tables, but what dictates how long the injector sprays for? Is it a constant value? or a multiplier table perhaps? Thanks for the help Mike.

[08VRSS]

Well i figured it out, i mapped out my cam timing, and adjusted my injection accordingly. Dropped my injector ms significantly in the upper range, and the car feels better to boot, no knock, no fuel pressure drop. Highest i saw was 6.9ms where before i saw 7.3ms at around 5200rpms. Lowered boost just a tad too.

This is as far as i could push it with a good opening in traffic, pretty good so far:

[08VRSS]

So far so good, i posted a screenshot of a pull yesterday in my above post. A big thanks to you, Bill, and overbooster.

[08VRSS]

It was the high injector ms that was concerning me, No fuel pressure drop yet, but now i figured out how to shift the window to lower it that's all. I'll be raising boost back up to 26 today and do some logging.

[cobaltssoverbooster]

injector physical limits dont change by spray time but other issues arise when approaching the 8ms range in most vehicles.
the spark event cannot be overlapped to a pre programmed injector window end cycle limit. the preset value for this gets you close but will not allow for you to over spray.
you dont need it anyways as changing it would just cause more problems you cant solve.... ex: wet spark plugs wont ignite properly

its been proved impossible to do on this setup about 3 times but everyone keeps trying to say no.

[cobaltssoverbooster]

on problem with spraying to soon is that the fuel if too much takes up a lot of space right off the batt which can causes a faster cylinder temp rise. i understand what your have done and are doing but the game to be played gets played with one of these:
https://www.avl.com/pressure-sensors...stion-analysis
the model i have has 2 additional sensors in it besides being a spark plug in the first place. requires special adapters and what not but i monitor cylinder temps and pressure to map the injector windows out to the most efficient spot. can be done with mbt method but the accuracy i can achieve is far greater with the sensor. pressure spikes and injector open angle do effect each other.

[projectlnf]

think there is a way to map out in excel or something and use a histogram on the scanner to input data to see where our injectors are stopping in relation to the spark event? and another question.. the top of the piston has the "cup" in it since we are spark directed DI wouldnt we want to utilize that cup in where the injector sprays? just a thought i have had my motor apart a couple of times and it poped in my head this morning

[projectlnf]

i hate how this thread is on page 3... this is some good stuff i wish people would try to ask more questions on here.

[cobaltssoverbooster]

I'm not surprised the ecotecs have died here. No one wants an lsj because you have to spend 10 k to make what a small turbo kit lnf makes and then the lnf just has to much going on discouraging the rest of the crowd.

Dying platforms

[codename Bil Doe]

Only reason I haven't posted much on the LNF is that it's all here but no one is asking questions. I haven't moved on to the LHU yet because I'm still racing the GXP. Next racecar will either be the ATS 2.0 or ATS-V. When that happens, then I'll dive headlong into understanding and helping unlock those ecu's.

edit: after all the sbc's and LS engines I've worked on, the LNF is by far my favorite. We're eventually going to drop one into my friend's 510.

[cobaltssoverbooster]

v8 lnf 3.6 l in solidworks beta design stages

[projectlnf]

allright i have a question on the picture that was put up how did you find out the opening and closing points of the cams??

[mbray01]

My only concern with opening the injector after the exhaust valve closes is the actual cooling of the exhaust valve. It's not air only but the fuel/air charge that cools the exhaust valve. I would be concerned with high boost/high load how hot that exhaust valve is getting. Not discounting what your saying. I get the idea of trying to control fuel pressure drop, by keeping the injector open for shorter periods of time, just throwing out there the years of research that went into keeping that exhaust valve cool. Just my 2 cents

[mbray01]

I see now, your initial description took me for a loop, that you was retarding injector pattern just for the sake of lower pulse rate. I see now you are modifying the injector pulse width because they changed as a result of cam changes. My mistake.

[projectlnf]

i noticed when i was injecting way early like 400 ish my EGT's came down and i completely cut out my knock at light throttle in boost situation.

[projectlnf]

Knock should be fully controlled by the rest of the tables. A lot of the tables you wouldn't think could cause knock cause knock. I would definitely not use injector timing to control it because that means an issue with another table still exists.

Also I am by no means an expert with EGT so someone please correct me if I'm wrong. From my research it appears you can have higher cylinder heat and lower EGTs and vice versa you could have lower cylinder heat and higher EGTs so I would be cautious with that.

I really think to keep it optimal you would need to check everything and redesign the entire table. GM tends to not be the smartest when it comes to tuning this motor. With that said, because of the amount of hassle and most people not wanting to do that I personally feel it's best to keep everything the same in relation for this table since it was acceptable factory. That would be the easiest safest way. Someone who knows more about this should chime in though.

your referring to injection timing in general?

its weird i have it to where im only able to boost 10 psi under 2800 rpm.. for cruising purposes and so i don't boost really low. i don't like it. and before the new injection tables i was throwing knock in that area. not cruising but when i flat foot it and it only boosts 10 i would throw like 3.7* knock but it was spiky. if that makes sense. it wasn't a full on knock in all cylinders

[projectlnf]

Something else in your tune is most likely causing you to see that knock. I keep all of my power 3500 and above but I have an aftermarket turbo so my turbo take me to 7000rpm no problem. I would look at everything for smoothness and no rapid changes and see what else you can find.

another note i should have added was i am speed density.. i still have the maf plugged in but the wire is no more. so the iat still works. i have smoothed and smothed and it seems like if i drier the car for a week or so on the same tune it will knock when i said up above. and reason i dont have a maf is because my relocate was in the hot side charge pipes.. i got the charge pipe for free with a ssqv. the trims would NEVER come anywhere i wanted them so so i said f it and went with dialing in fuel trims by the inj pulse mult i made a histogram and it works well