How is injector timing calculated?

[DSteck]

so i changed the boundry back to stock. made the smell worse. obviously. added 20 degree's to the ect table. so it seems i was actually on the right track the first time guessing with it vs the other way.

That advances the end of injection. If it works for you, more power to you!

[Area47]

in all honesty, the smell doesn't bother me, it's getting all the power that i can out of it, that's my ultimate goal by tweaking this final step.

advancing would make the injector fire sooner, IE when the exhaust valve is still open correct? or do i have it backwards.

[blkscooby]

So on a stock car it usually goes from ending 30* ATDC at idle to ending at 43* BTDC over 4k RPMs? It seems like you would want it ending later in higher RPMs.

Since the stock strategy is to spray on the back of the closed intake valve, at higher RPM, it sprays earlier in the cycle to allow more time for fuel atomization since the ms per rev is lower as RPM increases.

[blkscooby]

We already discussed this and came up with those numbers not guessing your cam is A typical though because it isn't super big. Your numbers were rpm 675, msec 3.3, boundary 530, ECT 110, EVC 27 ATDC:

530*- 110* = 420* <<<thats where the stock EOIT is at 675RPMs (60* ATDC)

3.3msec @ 675 RPM is 13.365*
27ATDC = 387*
387* + 13.4 = 400.4* <<< that's where you want your injection to end so for some reason adding 20* does make sense. DSteck correct me if I'm wrong.

What I have found is if you have positive overlap in your non-stock cam, you must ensure that the START of injection is after EVC, not the end of injection or the bulk of your fuel can still pass directly out the exhaust.

If you retard (move the injection later in the stroke) you add to the boundary or subtract from the adder tables.

[Kyne]

Since the stock strategy is to spray on the back of the closed intake valve, at higher RPM, it sprays earlier in the cycle to allow more time for fuel atomization since the ms per rev is lower as RPM increases.

Well stock at idle an LS2 it injects at 410*, the intake opens at 378*@.05 and with a 3.3ms injection that puts the start at 397*, 20* AFTER the intake opens so I'm not sure that is 100% true. But That was what I was asking, did you need that advance to make up for the RPMs?

What I have found is if you have positive overlap in your non-stock cam, you must ensure that the START of injection is after EVC, not the end of injection or the bulk of your fuel can still pass directly out the exhaust.

If you retard (move the injection later in the stroke) you add to the boundary or subtract from the adder tables.

In that example the start of the injection is right after the EVC thats why I added the 13.4. Positive overlap is one thing but more importantly is how the EVC changes relative to the stock location. in that example the EVC was 3* EARLIER than stock.

I THINK i understand everything except for the RPM tables so far.

[Area47]

pulling 20 from the ect table did the trick for the fuel smell. just need to either tweak the boundry off idle rpms, or the normal rpm tables to get the snap back in it.

it's actually becoming a lot clearer the more i mess with it

[Jamz]

Here are my latest tables.

Better fuel economy and no more fuel smell.

Hope this helps.

[DSteck]

Screw it. You guys have worked hard to figure it out.

Blue cells represent cells you can edit. For the Boundary, set it to the same number across the board. Crank Duration and Target EOI are values that are calculated.

In the table with ECT and RPM as axis labels, red cells mean you're ending EOI too early and will possibly fire while the exhaust valve is open. Green cells mean you're behind the exhaust valve closing. White means you're dead on. It is advised to use 0.006" lift values instead of 0.050" lift values.

Play with the blue cells to find your final values. I'd suggest not changing the boundary.

Also, note that pulsewidth is the fuel injector pulse width taken from the scanner plus the short pulse adder and voltage offset. You need to manually look these up. If your idle pulse is 1.0ms for example, go into your tune and look up the short pulse adder at 1.0ms. Add that to the pulse. Then, look at your battery voltage and MAP value. Go into the voltage offset and look that up, and add it to the pulse. 2.2ms is the final delivered pulse on my car with my ID1000s while idling at 800rpm.



I said there was nothing special. It's pretty simple and plain!

[Kyne]

You are the man!

I thought you were logging pulse width through different RPM and setting the entire RPM table, I guess it only matters around idle.

[SICK WS 6]

And I was thinking it might be more beneficial to get the lower ECT setup for cold start?

[DSteck]

I modify EOIT to clear the idle smell. I don't mess with colder sections because GM advanced it for a reason.

[carlrx7]

Screw it. You guys have worked hard to figure it out.

Blue cells represent cells you can edit. For the Boundary, set it to the same number across the board. Crank Duration and Target EOI are values that are calculated.

In the table with ECT and RPM as axis labels, red cells mean you're ending EOI too early and will possibly fire while the exhaust valve is open. Green cells mean you're behind the exhaust valve closing. White means you're dead on. It is advised to use 0.006" lift values instead of 0.050" lift values.

Play with the blue cells to find your final values. I'd suggest not changing the boundary.

Also, note that pulsewidth is the fuel injector pulse width taken from the scanner plus the short pulse adder and voltage offset. You need to manually look these up. If your idle pulse is 1.0ms for example, go into your tune and look up the short pulse adder at 1.0ms. Add that to the pulse. Then, look at your battery voltage and MAP value. Go into the voltage offset and look that up, and add it to the pulse. 2.2ms is the final delivered pulse on my car with my ID1000s while idling at 800rpm.



I said there was nothing special. It's pretty simple and plain!

Dave! You are the man! <3.. much love

should I change the PW for each RPM?

After all of this i ended up adding 7 to the lower rpm normal table.

Thanks again.

-Carl

[DSteck]

Like I said, I only use this for idle calcs.

[Jamz]

Hey Dsteck

1: With a more advanced eoit timing at higher revs. Does that equate to more torque and power on the dyno.

2: The RPM table ends at 4096rpm. Does it carry that number over for all revs above that level Or revert to 0?

3: The L98 advances EOIT alot up top. Do you peg 520 across the board for the L98 motors also or leave the advanced table?

Thanks i advance

P.S. Thumbs up for sharing the spreadsheet. It will help alot of people!

[Area47]

thank you for caving in sir.


most certainly appreciated.

[DSteck]

Please note I posted this to just help visualize when events happen. I don't have instructions on how to set EOIT for power/fuel economy/ending world hunger.

Yes, it takes the 4096 value and carries it.

[Area47]

Please note I posted this to just help visualize when events happen. I don't have instructions on how to set EOIT for power/fuel economy/ending world hunger.

Yes, it takes the 4096 value and carries it.

does it help me visualize whirrled peas?

[DSteck]

does it help me visualize whirrled peas?

If you close your eyes and think hard...







No.

[IDRIVEAG8GT]

does it help me visualize whirrled peas?

[Area47]

If you close your eyes and think hard...







No.

DAMMIT!

that's what i was after the whole time.