Injection timing help w/ cam

[5_Liter_Eater]

Subscribing as I'm interested in playing with this on my new TT 422 LSX w/ E40. advertised intake duration is 284 @ .006" with 116 ICL, although the cam has 4' advance ground into it so I'm not sure whether to use 116 or 120. Gonna try it with 116.



Advertised (.006") duration valve events:
IVO is 26.0' BTDC ( - indicates ATDC)
IVC is 78.0' ABDC
EVO is 93.5' BBDC
EVC is 25.5' ATDC ( - indicates BTDC)
Overlap is 51.5'

So based on the above:

Advertised duration at .006 = 284, centerline = 116

284 / 2 = 142
111 - 142 = -31 --> 31
31 + 360 = 391
391 + 10 = 401
401/ 2 = ~200

So on the EOI ECT target, replace any number under 200 with 200 after zero'ing out the RPM EOI right? Current numbers are 110 so that seems like a huge difference. Why would the target change with cooler ECT's? Seems like it should be static. And whats the reasoning behind zeroing out the RPM table? I guess to keep it ~static as well.

[itsdaveonline]

Lots of questions and cam cards in here. Not alot of answers lol. There is like a 20 page thread on this but lots of theory and not many answers in there either. Perhaps some one can start us out with the basics on a Gen 4?

My question in post #19 would probably clear up some confusion

[dcpatters]

RussK set mine to 90. Motor feels better, idles smoother, albeit has 15* of overlap.

But I agree, I have read so many theories.

[07GTS]

520-110=410 eoit if u want to delay it u need to lower the ECT table, my EVC is at 388.5 and at idle 900rpm inj pulse duration is 8.1 deg (EVC 388.5 + inj dur 8.1 = 396.6 ) so i would calculate it at 520-124=396 so it is actually fine set at the standard setting of 110 for the ECT because it is delayed even more, or then also cruising at 2000rpm using injector pulse of say 3ms which is (EVC 388.5 + inj dur 36 =424.5) it is 520-95= 425 eoit, i have gone a bit further with mine which ill be testing on the next decent weekend to see what the results are but so far the under 2k rpm has been cleaned up alot and drives smoother with just changing the eoit

[realcanuk]

The very first post in my link (my link jumps to post 260), divide advertised duration by 2, subtract that from the intake centerline, swap the negative sign add 360 to get to TDC, then add another 10 to put the fuel on the back of the valve...then like I said, divide that by 2 for HPTuners...leave it alone for EFILive...then if you scroll down on the same thread to post 269 (my post) you'll see I laid out the math for my cam. B1206 in the EFILive system is the RPM table in HPTuners to zero out, and B1205 is the ECT table where you enter the math into the normal operating temp...anything lower than that math, just set it to the same value, anything higher, I leave alone.

I don't know the advertised duration on your cam, but your intake centerline is within 1 degree of mine, and your intake duration at 0.050 is also within 1 degree...my cam is 226 on the intake with a 110 (109.6) ICL...yours is 227 on a 109...so the math will be basically the same.

So that said, I think you should zero out the RPM rise table, then go into the ECT table, under Engine - Fuel - Injector Control - Injection Timing - Normal ECT, and make it look like the attached picture. Leave the boundary table at 520.

Attachment 51904

This is interesting because using this method the numbers are very far from what I got using the spreadsheets available. My calculations with this method bring me to number similar to the picture you posted. My car is running great the way it is but I would like to try to reduce the smell at idle. I will try this method and see if it helps.

[Michael_D]

Have you guys tried to use DSteck's handy-dandy super-duper Gen IV spreadsheet??

I know some don't think you should screw around with the boundary, and maybe you shouldn't.....I don't know for sure. But I can say that it helped in my case to raise it 25. GHuggins suggested I try that, and it did seem to help a bit. Point being, I don't' think it should be one of the holy grail tables that you "shall not touch"......

Dave's spreadsheet:

EOIT Calculator.xlsx

[realcanuk]

Have you guys tried to use DSteck's handy-dandy super-duper Gen IV spreadsheet??

I know some don't think you should screw around with the boundary, and maybe you shouldn't.....I don't know for sure. But I can say that it helped in my case to raise it 25. GHuggins suggested I try that, and it did seem to help a bit. Point being, I don't' think it should be one of the holy grail tables that you "shall not touch"......

Dave's spreadsheet:

EOIT Calculator.xlsx

I did mine using his spreadsheet. Car runs great. I am playing trying to reduce the smell a bit at idle, but maybe its as good as it can get. I really don't know.

[5_Liter_Eater]

Yea I've been playing with the spreadsheet and I get green numbers to about 1900, white to 2100, fading into red after that. Which seems good, but thats with the stock numbers and my cam and IDC numbers.

Stupid question but here it goes: My understanding is EOIT is (Boundary - RPM - ECT), as shown by this pic from the other thread:



So if thats the case, then the SOIT in degrees is however many degrees the crank moves in however many milliseconds the required pulsewidth is for a given RPM and load. Correct? OK. So with big injectors and low RPM this isn't a problem, but that window in the pic still looks really small in order to spray the required fuel after the exhaust valve closes and the EOIT is reached, especailly as load increases and more pulsewidth is required, it's going to have to spray earlier, with the exhaust still open. Which is what Dave's spreadsheet shows in red. It seems like with the EOIT numbers it's wasting most of the intake stroke. Clearly I'm not thinking of something right and I feel stupid but I want to understand this better.

[07GTS]

if for example the best and latest time to end injection is at 450 deg (half way down on intake stroke) then to get that set up boundary to 520-ECT 70=450 eoit, then every single injection will be finishing at the latest point and if it fits in after the EVC then u save fuel and smell but it will get to a point at where the pulse duration will be too much and have to spray on a open valve no matter what, so with mine at EVC 388.5 deg i would have any injection duration up to 61.5 deg will be after EVC and any over starts to spray at the open valve

[5_Liter_Eater]

Obviously I'm ignorant about engine/fuel dynamics/atomization but the stock values seem backwards to me. The RPM EOIT adder table increases as RPM's go up, decreasing the crank degrees the pulse has to do it's job inside the intake stroke and before the exhaust valve closes. Seems like the RPM table should decrease as RPM's go up, allowing more of a window to fill the chamber while the exhaust valve is closed and the piston is on it's way down on the intake stroke. As it is now it increases with RPM forcing the injector to spray more and more into a chamber with an open exhaust valve. Perhaps it's not ideal to spray past halfway down the intake stroke but it's got to be better than spraying when the exhaust is still open and, in higher pulsewidth situations, while the exhaust stroke is still finishing. #SOCONFUSED

[realcanuk]

Have the same issue. I have gone through this 100 times and still not sure I understand. That is why I originally went with Dave's spreadsheet and called it a day. Now I am trying other things to try and reduce smell, but I feel I am almost trying blindly, which I don't like to do.

[dcpatters]

Have the same issue. I have gone through this 100 times and still not sure I understand. That is why I originally went with Dave's spreadsheet and called it a day. Now I am trying other things to try and reduce smell, but I feel I am almost trying blindly, which I don't like to do.

Are you increasing the Normal ECT values or reducing them?

[itsdaveonline]

Bill - don't worry im still confused here too. Hopefully were all talking the same language here.

But my best GUESS is that the rpm eoit adder has higher figures towards higher rpms is because you'll want the injection to finish sooner at higher rpms. With more fuel required at higher rpms it will take the injectors longer to deliver all that fuel plus the valve events will be occuing faster relative to time & rpm. So with that being said you'll want to buy extra time by injecting earlier.

My understanding is eoit = boundary - rpm - ect and based of earlier posts that lower final eoit calculations will advance injection while higher final eoit calculations will retard injection.

It just so happens lowering the ect value actually retards the injection.

[5_Liter_Eater]

I think for the pusposes of this thread we need to agree on the definition of advance and retard. The way I think of it is, retarding injection will make it happen later, advancing it will make it happen earlier. So the higher the final EOIT number, the earlier the injection happens (advance).

[dcpatters]

So the higher the final EOIT number, the earlier the injection happens (advance).

I believe this is what Dave mentions in post 101

http://www.hptuners.com/forum/showth...lculated/page6

[itsdaveonline]

So the higher the final EOIT number, the earlier the injection happens (advance).

I was thinking the opposite?! If you end injection / eoit @ 300 degrees then it finishes injection later (retards) compared to an eoit of 200 which would finish sooner (advanced)

Yeah let's start with the basics. We're all obviously confused lol

That thread is mostly gen3 stuff which i think is fundamentally different on how injection timing is set in the tune

[5_Liter_Eater]

It's a gen four specific thread. I have purposely not looked at gen three injector timing so as not to get even more confused.

My LSX will be up and running and driving this weekend. Once I get the tune lined out as it sits now I'll play with the EOIT. My initial thought is to zero out the RPM table which will fix the EOIT at 410'. If I get good results from that then I'll use the RPM table to take even more away to allow a closed exhaust valve spray in the upper RPM's.

[realcanuk]

Are you increasing the Normal ECT values or reducing them?

Here is what I came up with using Dave's spreadsheet... I have been using the since last year and the car runs great.

old eqit.PNG


Here is what I am trying, based on info given in this thread. (in hopes of reducing the smell at idle). The car also seems to run great with no changes. It is hard to know for sure, but I don't believe smell is reduced any, so I think for now I will go back to the first setup.

new eqit.PNG


Any thoughts on these ??

[GHuggins]

Here is what I came up with using Dave's spreadsheet... I have been using the since last year and the car runs great.

old eqit.PNG


Here is what I am trying, based on info given in this thread. (in hopes of reducing the smell at idle). The car also seems to run great with no changes. It is hard to know for sure, but I don't believe smell is reduced any, so I think for now I will go back to the first setup.

new eqit.PNG


Any thoughts on these ??

OK, I'm confused... Did you not advance the injection timing on both of these? Added 10 degrees at idle with Dave's then 87 with this threads directions? (if I'm thinking correctly - not really sure if the ect based table is a full degrees worth of change or not if you change it one degree - never went in line with the other tables when I would mess with it). Which would explain why it didn't make any difference possibly...

What happens if you add 20ish to the boundary in the idle rpms? Or in other words retard the injection timing? That's if the other tables are back to stock...

Please don't take this post wrong either as I'm not 100% on these tables either. Reread the post and wasn't sure if it would come off negative or not. Was not my intention if it does. Sorry if it does. Was just curious if the way I've been doing it and advising others to do it makes any impact on yours...

[07GTS]

adding to the Boundary delays injection, or subtracting from the ECT and RPM tables delays injection, the ECT and RPM tables are adding to the boundary as in advancing it, boundary of 520-ect-rpm=eoit because its end of injection all events (ect and rpm tables) are adding to before that point working backwards