Injector Timing? Reference Periods? refereencing what?

[Higgs Boson]

I was getting desperate, my man....

[PitchblackC3]

This is good discussion:
If I understand this correctly on my LQ4:
stock cam: 196/207 116LSA 0 advance gives me
EVC -12.5
Degrees 347.5

My new cam is 222/226 112LSA 4 advance gives
EVC -3
Degrees 357

difference = 9.5

Stock Boundary is 6.5 with 5.55 normal

Shifted normal: 5.66
Actual Normal: 6.18


I am kind of unclear on the meaning of "shifted normal" and "actual normal". Should I be setting normal at 6.18, or shooting for a value between 5.66 and 6.18?

[Higgs Boson]

I just wanted to update on my smoke at idle issue. It was all due to closed loop operation. I'm running open loop only and no smoke. ECU couldn't figure out my cam and headers at idle and just added too much fuel and Im not tuning CL any more. It runs better in OL.

[pontisteve]

The O2 sensors mistake cam overlap at idle for excess oxygen, and try to richen up the mixture. Since it can never get rid of the excess oxygen at idle, the problem could just get out of hand. This is why the wideband also always reads lean at idle with a cam.

One more reason to tune in open loop with a wideband. Once idle is tuned, I usually turn closed loop back on and see what the fuel trims do. If they start trying to move the mixture substantially, then we have little choice but to turn them off.

Heating the O2's up more can also help, if that's possible. On Fords, heater duty cycle is calibratable. I haven't seen that on the GMs so far as I am aware.

[Cruz-Lo]

I know this is the gen 3 thread, but im interested in learing how the gen 4 tables work. E38.

I searched but cant find any threads about this subject in Gen 4. I see all the values are actual degrees.

Seems the final eoit is the "boundary" minus "normal ect" minus "normal rmp"

When I ad this up I get 360 ish values which seem to be correct.

So i need smaller numbers in the Normal rpm table to extend the eoit.
Or bigger numbers in the boundary...

??

[pontisteve]

Can't contribute here, but please post whatever you end up finding out.

One would think that like Fords, GM would put in actual injection timing values in the tables. Obviously that was not the case with the LS1. Maybe they do that now with the newer processors?

I would stick with changing the normal table, not the boundary table, since it affects all the others.

There's still the argument, depending on cam size, as to whether you should end injection time earlier or later. It seems clear that large cams want later, but I'm not sure how big a cam has to be to make that choice one way or the other.

[CLRD4TO]

Had a rainy day today and read this entire thread. Great discussion! However, little results for me. I changed the Normal and Makeup to 6.24 at operating temp, calculated from the worksheet. Great work Sound btw! AFR's didnt change much, throttle response is just as snappy as it was before, and the exhaust still stinks like hell. I did notice the idle likes to hang a bit until the car comes to a complete stop. I will touch up the idle tuning another day.

[DrkPhx]

CLRD4TO - Are you Jared?

Even though I'm an EFILive user I've read this with interest because I played with injector timing a couple of years ago with no noticeable results other than positive LTFT's and not so good tip in. I have a 98 TA with a LS2 402, big cam, large stall, gears etc.

Anyway, I decided to give it another shot. So I used the calculator here based on my cam valve events (26 degrees of overlap, etc). I used the True Normal value from 176 F up and increased the lower ECT values, but only by the same rate of change as stock (make sense?). I included the actual values below. I also copied the same values into the Injector Timing Trim table as well (which I didn't do my first attempt at this). This time the results were very noticeable; for the better. The car ran and idled well before, but it's even better now. As mentioned by others, the engine is much quieter now at idle and better low rpm driveability. The smell is still there but not as bad. Cold start seemed to improve as well. The fuel trims have not changed and neither did the WB AFR.


LABELS Injection Timing (mS)
ECT °F Value
-40 1.988281
-18 1.988281
3 1.988281
25 1.988281
46 1.988281
68 1.988281
90 2.617188
111 3.230469
133 4.195313
154 5.671875
176 6.378906
198 6.378906
219 6.378906
241 6.378906
262 6.378906
284 6.378906

[CLRD4TO]

CLRD4TO - Are you Jared?

I also copied the same values into the Injector Timing Trim table as well

Hey Gino!

I cant seem to find this trim table anywhere. It is by chance just efilive?

[DrkPhx]

Hey Gino!

I cant seem to find this trim table anywhere. It is by chance just efilive?

What's up? They may be called something else in HPT. Here's a description:

This table modifies the timing of the additional pulses that maybe required after the
- {B3702} Injection Timing offset limits are reached.
These values should not exceed those in
- {B3702} Injection Timing.

After comparing a log before and after adjusting injector timing, I noticed the injector duty cycle went down as well.

[Throttle]

i used Jimmys excel spread sheet for the Normal and Make up,I immediatly noticed my AFR on my wideband to be a little more steady and throttle response is better,I have to agree that this method works.In my Normal and Makeup tables i just added the difference from stock accross to entire table by entering the value in the white entry box and click on the add icon.

[wyochimneysweep]

Heres my math I just did.
my intake vavle opens 20 degrees btdc.
so my boundary and normal at 190 degrees temp is
6.10 and 5.9
D=-784+((6.1+5.9)*90)
D=-784+(12*90)
D=-784+1080
D=296
So I know my IVO at 340
So
340=-784+((6.10+N)*90)
340+784=-784+784+((6.1+N)*90)
1124=(6.1+N)*90
1124/90=(6.1+N)*90/90
12.4=6.1+N
12.4-6.1=6.1+N
6.3=N

then take 6.3/5.9=1.07
so take the normal table and mupt by 1.07 cross the board
lets check the math
D=-784+((6.1+6.3)*90)
D=-784+(12.4*90)
D=-784+1116
D=332
so in theory my injector should be done before the vavle opens.

[wyochimneysweep]

flashed it and seems to be running better but now its a new day and looking at it why is the stock ref 296? isn't that way before the vavle open on a stock cam?

[Higgs Boson]

what lsa is your cam on? it's pretty small.

[wyochimneysweep]

114. I didn't want to move the power band up to high since its a pickup and i tow

[JimMueller]

Just stumbled across this thread, so let me see if I understand this. Here are my valve events:

.006
IVO 25.5
IVC 65.5
EVO 73.5
EVC 51

.050
IVO 1
IVC 41
EVO 49
EVC 1

My 98's boundary: 7.22
Normal/Makeup at operating temp: 4.55
Idle: 850
IPW: 3.5ms @ idle

Which of the numbers in the blue cells in the bottom table do I want to apply to my normal/makeup tables? Do I use the percentage difference between the new value and old value and apply that percentage to the whole table, or do I use the +/- difference and apply that to the whole table? Do we change the boundary? The only other cleanup is recalibrating the VE/MAF tables?

Edit: Re-reading the last few pages of this thread again, I'm inferring you 1) keep the boundary field the same, 2) apply the difference between your current engine warm normal/makeup tables and the spreadsheet's Actual Normal cell. If that's acurate, which Actual Normal cell (EVC/IVO/ISP EVC/ISP IVO) are we using? For the cam timing, it seems like it's preferred to use the seat timing - but I can't find seat timing durations for the stock cams.

To get a better idea of how the values change between the settings, I remodeled SoundEngineer's spreadsheet for my own use, hopefully I got it right? Tonight I added .945 to both tables and re-checked RAF & VE. No change in RAF, I added 1-8% <=1200, and 1-5% 1600-3600. I'll drive it for a few days to see if that helps my bucking & overshoot problem.

[hymey]

Just my experience. With e38s I increase the inj timing value to advance injector timing around reversion areas and idle to stop fuel blowing down the ex. To stop reversion I advance it. I have advanced and retarded quite a bit going either way doesnt seam to affect torque just stop low end miss or surging whilst stomping the throttle. I tuned a full weight VE/G8 that ran a 10.82 with a LS7 264/270/110 . The engine broke down severely and was not happy until I advanced the injector timing considerably I did not have to touch the VE table at all it just started to burn the charge and torque went through the roof. A trick I used tuning aftermarket engine management was leave the pulsewidth the same and advance or retard timing till mixtures were the richest then you would no if the inj timing was in the ball park. Dont get overly mixed up with injector timing numbers just finish the event before IVO and it will be close. Efilive works it out differently and I understand how it works there I made some changes to see what effect it made when I pulled the tune with hp and I could see I was in the right direction bigger numbers definately advance timing in the e38.

[pontisteve]

It should be that bigger numbers increase the DELAY, meaning the injector fires later in the cycle. The main idea being that you are firing the injector after valve overlap. While you end up firing the injector onto an open intake valve, you do lose some fuel vaporization that way. But, you aren't losing that fuel right out the exhaust valve, so its still an improvement on cars with big cams.

If you advanced EOIT, you would fire on a closed valve, vaporize nicely, the intake valve would open, and that nice vaporized fuel charge would go right out the exhaust valve due to overlap. The trick is to delay injector timing until after the exhaust valve fully closes. This means advertised duration, not duration at. 050.

[Wnts2Go10O]

It should be that bigger numbers increase the DELAY, meaning the injector fires later in the cycle. The main idea being that you are firing the injector after valve overlap. While you end up firing the injector onto an open intake valve, you do lose some fuel vaporization that way. But, you aren't losing that fuel right out the exhaust valve, so its still an improvement on cars with big cams.

If you advanced EOIT, you would fire on a closed valve, vaporize nicely, the intake valve would open, and that nice vaporized fuel charge would go right out the exhaust valve due to overlap. The trick is to delay injector timing until after the exhaust valve fully closes. This means advertised duration, not duration at. 050.

mine is setup to try and take advantage of the scavenging created by the overlap

[pontisteve]

mine is setup to try and take advantage of the scavenging created by the overlap

Not sure I follow you. There's nothing about scavenging and overlap that is good for injector timing. For horsepower, yes.