Need Direction on EOIT Injector Timing for Big Cam Gen 3 ECU

[Danspeed1]

Hello,

I am hoping someone can lead me in the right direction. I have been chasing a rough idle (at warmup), lean tip in (under certain conditions), and constant raw fuel smell. To complicate things a bit more, this is on an 0411 swap I did to a big block. I've got 100+ flashes to the ECU and once warm the car runs fantastic other than the lean tip in (occasionally) and the horrible raw fuel smell. After a lot of research I have narrowed the issue down to what I believe to be EOIT. I have been pretty fortunate to have grasped just about all the concepts on google and HPT forum. This just seems to be something that is not clicking, I'm honestly lost. I read the 25+ Page dissertation in regard to it on here, but honestly it left me more confused than anything else. To complicate this a little more, I am using a 0411 ECU with a 02 Suburban 5.3 tune file that has been revamped to run the older style big block. So I was able to draw the conclusion that there is an issue based on a comparison of both tune files. I am going to post below all of the information I have accumulated. I am hoping someone can point me to a definitive conclusion as to how to set these two tables or better yet a set of guidelines to use when calculating this and setting the tables for this in the future. I think part of the problem is, there seems to be more GEN 4 information on this topic than GEN 3, and the information seems to flow together in a way that makes it harder to understand. Or I'm just not that smart, that's very likely as well . Hopefully this thread will serve the purpose of outlining some sort of process for those seeking to fix the same in the future.

Current File Settings - Pretty generic for most GEN 3 4.8, 5.3, 6.0 SB
EOIT Gen 3.JPG

This is a screen shot of the stock settings removed from a Vortec 7400 which would closely resemble my engine if NOT for the cam
EOIT 454.JPG

This is a copy of the specifications of the Cam used from Comp (Part#11-423-8 XR27HR-10)
Cam Card 454.JPG

Here is a copy of the cam card from the engine builder. It appears as though he advanced it .25 degrees from the centerline
21324-MMS-1546447949375-attachment1-20190102_115030-1.jpg

I believe this is what really confused the heck out of me. This seems like a great comprehensive tool, but unfortunately I can't seem to put it together. This was removed from an HPT forum thread that was posted in Feb of 2018. I don't know who to credit it to, but as you can surmise from my lack of understanding it, I sure as hell didn't create it.

DWR SOIT EOIT Worksheet 041715 (1).xls

-Dan

[cobaltssoverbooster]

i think i ran this cam before and used numbers varying from 5.95 to 6.24 for the normal table
i settled on them after using an LS1TECH excel sheet and verifying wideband errors between changes. I can't say i know how to use the sheet you found but if you have good luck with these numbers then at least you have a starting point.

Edit: original post has wrong table values...see below re-post of table.

[Danspeed1]

Thank you for the response back. I appreciate the answer to my question. If you are able to break down what is actually occurring any further I would appreciate it. I am trying to understand in Layman's terms (from the point of "this is occurring, then that is occurring"). What I take away from what you posted above is I should leave the boundary at 6.5 and changing all the entire table of normal values from 5.55 to 6.24 and should leave my injectors spraying after the exhaust valve is completely closed, and while the intake valve has just lifted off the seat?

What is "new" normal vs "true" normal?

Also, if you are able to post the calculator you are using that would be appreciated as well.

Thanks again

[cobaltssoverbooster]

Boundary is the full window term. it designates the allowed range. Normal and Makeup are subtracted from the boundary to determine the EOIT. i typically leave EOIT boundary alone until i start pushing huge cam duration values of around 270+ at advertised .050. after that i extend the range and just play with the numbers until i decide im happy with what i have through the mid range power gains. at huge lift smell is inevitable so i just disregard that and go off of performance. in your case you should be able to limit the smell a bit. Dont expect it to go away though.

Bluecat did testing a while ago...like 2009 or earlier and from his work i understand a full term 1.00 is 90* of rotation. 0=0* and 8=720*. this means .1 is ~= to 9* shift. I personally dont really go off of this math as an exact be all correct because each head has some variance in scavenge performance due to port shape. so one head may pull a little harder than another etc.... so i use the calculators to get close and then start doing dyno pulls testing mid range performance until the change doesnt net any significant gains. then the normal limits are tailored to the setup. if you leave the fuel tables alone you can effectively do a similar test by making a change and watching the fuel error between changes. if the difference tells you that the change made it richer (need to pull fuel) then you can assume the cylinder became more efficient. I tend to try and verify the gain by watching ve and maf airflow for any sign of gain after the fueling is corrected. if it went richer and i fixed the fueling event but the maf and ve went down then i disregard that last change. This is all personal preference so you would have to take it for whatever it is worth to you. Since im no longer a shop and work on my own stuff only, i tend to have time to waste by testing these out the long way.

Im no master at this topic but this is what i have come to understand. Past this the depth of my knowledge on the subject tapers off pretty hard.


New is a mathematical calculation and true is based on cam card references. Most have better luck on the smell factor using true values.
the calculator can be downloaded in post #2
https://ls1tech.com/forums/pcm-diagn...eoit-help.html

[anniversaryss]

Cobalt what would your opinion on setting EOIT for a 234/244 110lsa cam?

[Danspeed1]

This is the best explanation I have read yet. Thank you for taking the time to do that. What you have explained so far makes sense. So in essence I want to get within the boundary based on the "math" and then adjust to taste after that. I think I am still having trouble understanding the math. I downloaded the calculator above. Here's where my next little bit of confusion comes in; with a normal injection target of 5.55; the event should occur 300.5 degrees into the 4 stroke cycle. Yet (90x5) = 450 + (5.5x9)) = 499.5? . What part of the equation is still missing? Also I noticed in the calculator you showed above

Exhaust Valve Closing AFTER Top Dead Center: at 27 degrees
Exhaust Valve Opening Before Top Dead Center : at 32 degrees This makes sense (removed directly from cam card)

But where does the values for "NEW" exhaust valve closes after TDC and "NEW" Intake valve opens before top dead center come from?

Sorry for all the questions but I am really interested in understanding exactly what is going on here. I'm trying to paint a picture

[Danspeed1]

4stroke.JPG

Also, I want to make sure I have the correct mindset here. We will use 5.55 as a number to signify a fuel injection before the intake valve opens. With a stock cam, there is basically no overlap correct? So GM sprays fuel on the intake valve halfway through the exhaust stroke so the fuel has time to evaporate. However as a result of the newly added overlap due to the big cam, as the exhaust valve is closing and the intake valve is opening now simultaneously, some of that fresh air and fuel is also escaping out the exhaust valve? This is giving me the raw fuel smell and the mediocre idle quality. What we are accomplishing by moving the NORMAL table from 5.55 to 6.24 is causing the injector to fire later in the stroke so the intake valve is already a little bit open and the exhaust valve is just about closed so that less raw fuel is escaping. Am I on the right track?

[Danspeed1]

Cobalt what would your opinion on setting EOIT for a 234/244 110lsa cam?

Hopefully we can get to some sort of conclusion or process here so this can become something very simplified and repeatable so we don't have to keep asking those in "the know" what to set it at. That is the whole goal of my thread. There has to be someway to figure this out so it can be tweaked on all of our setups.

[85K5Jake]

Hey Dan heres another Excel worksheet you can try. I've used it and it pretty good. Really cleaned up the throttle response and fuel smell at idle for me. Its a bit simpler than the one you posted. A cam math worksheet also.Copy of EOIT Worksheet based on EVC.xlsCam Math.xls

[cobaltssoverbooster]

Cobalt what would your opinion on setting EOIT for a 234/244 110lsa cam?

probably 6.0-6.3 normal with stock boundary of 6.5

[cobaltssoverbooster]

This is the best explanation I have read yet. Thank you for taking the time to do that. What you have explained so far makes sense. So in essence I want to get within the boundary based on the "math" and then adjust to taste after that. I think I am still having trouble understanding the math. I downloaded the calculator above. Here's where my next little bit of confusion comes in; with a normal injection target of 5.55; the event should occur 300.5 degrees into the 4 stroke cycle. Yet (90x5) = 450 + (5.5x9)) = 499.5? . What part of the equation is still missing? Also I noticed in the calculator you showed above

Exhaust Valve Closing AFTER Top Dead Center: at 27 degrees
Exhaust Valve Opening Before Top Dead Center : at 32 degrees This makes sense (removed directly from cam card)

But where does the values for "NEW" exhaust valve closes after TDC and "NEW" Intake valve opens before top dead center come from?

Sorry for all the questions but I am really interested in understanding exactly what is going on here. I'm trying to paint a picture

i re-ran your specific values and i get a normal range of 6-6.5 with stock boundary of 6.5
the old are settings for a stock camshaft. typically they are EVC= -15 and IVO=-19.5 for a stock LS1 camshaft.
The New EVC and IVO values are for your cam card specs. you should get something like this if i use your cam card:
EOIT Card.JPG

[Danspeed1]

EOIT Card.JPG

So based on the numbers you posted (from my cam card). The Exhaust valve is completely closed at 387 degrees however the intake valve began to open at 328 degrees. This leaves an overlap of 59 Degrees. Based on my reading in the long thread about this you want the injector to begin spraying at about 10 degrees before your exhaust valve is completely closed. So my NORMAL value should be 6.41.

This is going to bring me to my next 2 questions.

#1 Where is the 387/328 value calculated from. I realize its based on degrees of the 720 degree cycle but how is it calculated.
#2 This EOIT NORMAL Value fits into 154 degree and up category but how are the colder temperatures calculated (ex. 2.55)

EOIT 454 #2.JPG

[Danspeed1]

Hey Dan heres another Excel worksheet you can try. I've used it and it pretty good. Really cleaned up the throttle response and fuel smell at idle for me. Its a bit simpler than the one you posted. A cam math worksheet also.Copy of EOIT Worksheet based on EVC.xlsCam Math.xls

Great Calculators... Please check my math but I think this is the first two calculators I was actually able to figure out!

Cam Calculator.JPG

Cam Calculator 2.JPG

I'm pretty close to the correct values here; and notice something interesting which I posted in regard to before... the calculated degrees of the cycle is 499. I put a red arrow next to it. So I still don't understand why the shifted EOIT value reads in the 300s. I would still love to know how that value is calculated. This seems like the easiest calculator to use so far though.

Thanks for the input guys... learning a lot today!

[cobaltssoverbooster]

yeah looks like you may have figured it out. That would be a decent starting point. some users have better results with higher normal numbers but that is application to application.
6.4 isnt unreasonable...i have heard some users as high as 6.5-6.8 depending on cam performance in their application. Notice the true normal result based on cam profile at .000 is like ~6.58....people often use the true normal values as inputs.

[Danspeed1]

I am going to start using that value. Basically if it smells less, and I can get my VE dialed back in all less than 2% again, and (hopefully the tip in issue goes away) I will leave it. I agree, I don't think there is much performance to be gained, especially on an older big block.

Anyone have any further thoughts on post 12?

Dan

[anniversaryss]

probably 6.0-6.3 normal with stock boundary of 6.5

So are we changing the normal where it only says 5.55 stock or an equal amount across that table?
Also just leave the boundary at 6.5 no need to change that?
What's the diff between New and True normal ?

[85K5Jake]

Anniversaryss when I did mine I figured the difference in % between old and new values and just multiplied the the whole table by that %

[cobaltssoverbooster]

So are we changing the normal where it only says 5.55 stock or an equal amount across that table?
Also just leave the boundary at 6.5 no need to change that?
What's the diff between New and True normal ?

i would run by percent shift to keep the temperature fluctuation in check. at cold temps you have more dense air so you dont need as much delay effect.
with a stock boundary of 6.5 and in reference to a stock normal of 5.55 at temp:
8.1% increase @ 6.0
13.5% increase @ 6.3

[JakeFusion]

With a similar cam, I ran 6.25 and it was fine.

I actually kept the stock EOIT values below 154 degrees. Seems to run fine in the cold with stock settings there.

[anniversaryss]

i would run by percent shift to keep the temperature fluctuation in check. at cold temps you have more dense air so you dont need as much delay effect.
with a stock boundary of 6.5 and in reference to a stock normal of 5.55 at temp:
8.1% increase @ 6.0
13.5% increase @ 6.3

Sorry dont want to seem so naive.
So your saying as JakeFusion said changing the values at temp your meaning just the 5.55 values which is anything over 154 degrees?