Injector End Angle Tuning

[81 TransAm]

A lot of tuning issues can be related to sub-optimal IEA settings.

I agree. It made a big difference in my tune. My cold starts have always been very good. But it does feel a little better if I start it cold and put it in gear right away, without waiting for it to warm up a little. On a steady cruise when I go to accelerate a little, you can see the IEA increase as the IPW increases. With the old setup, it would not have increased the IEA under these conditions.

[allan5oh]

Just wanted to add, I don't think the Y axis needs to be anything above 20 IPW:
@ 5000 RPM 100% DC is 24 msec
@ 6000 RPM 100% DC is 20 msec
@ 7000 RPM 100% DC is 17.1 msec
@ 8000 RPM 100% DC is 15 msec

[81 TransAm]

I just looked at some datalogs and my WOT IPW is around 15 msec. But in the winter time, I have some cranking IPW at around 30 msec. I probably could tweak my scale a little.

[allan5oh]

You could just do a simpler 1D graph for Cranking Fuel above 20 ms. Just have to make sure the two tables aren't cumulative and if they are compensating. Another thing, I bet Advanced Control can be set higher when IEA is optimal.

[allan5oh]

I have yet another thought. If one wanted to gain X axis resolution with two maps. Have the RPM two furthest right columns on the low RPM map match the two columns in the high RPM map. Have the furthest right column in the low RPM map as 0° IEA and the furthest left column in the high RPM map as 0° IEA. The computer should blend between the two maps and the resulting IEA should be fine. It's just like an extended map.

[allan5oh]

Well I went ahead and lost my mind! I made a spreadsheet to calculate when the IEA needs to be so that the beginning is right at exhaust valve close. It is attached. Any protected cell has a formula, the password is Holley. I accept NO RESPONSIBILITY USE AT OWN RISK!
EDIT: This spreadsheet has no consideration for port speed.

[allan5oh]

Here's the current Global File. I used two Advanced 2D Tables. One is for lower RPM the other higher. The lower uses a 10 ms as the Y axis, the higher 20. I used the spreadsheet to calculate optimal injection considering overlap let's call it the 81TransAm method (this method has no consideration for port speed). Then I used the S2H method of zeroing out the fuel table and using the Holley calculator. I did NOT offset to 0. I now have FOUR IEA tables with the Y axis as IPW, which is far superior to MAP.

Then what I did was blended the two methods. Whatever table had the more negative value, that is the value I used. What this means is if the PW could "fit" in between exhaust close and intake BDC then the injection event STARTS at exhaust close. If it doesn't fit then injection ENDS at intake BDC. I understand this likely isn't optimal, more data is needed especially dyno time, but I think this is the best way to do it. One thing that is ignored is port speed with the spreadsheet, it just assumes the injection gets there instantly. But I also think the Holley calculator ignores port speed, it only considers distance and RPM ignoring port cross section. Port speed can be extrapolated using a well tuned base fuel VE table and port cross section, but that will come later when the car is better tuned. This means the "flat" areas of the IEA tables will no longer be flat.

The right column of the low RPM table is zero and the left column of the high RPM table is zero. This is so they blend properly. There's a bit of resolution lost in between the two but no big deal as we don't spend much time in that RPM range anyways.

Once I get more data time I'll be able to refine the math. At that point the calculated port speed and time from injection to valve in crank degrees will be more accurate. Then I will take that table to replace the S2H table, plus add the new table to the 81TransAm table. Again blend the two methods and the resulting IEA table should be perfect across all loads & RPM.

[81 TransAm]

Wow. You really have put a lot of thought into this. I used your worksheet and came up with the same numbers I did, but a lot faster and didn't have to do the math.

[allan5oh]

Well that's good, because it means we both did the math correct. The nice thing about the spreadsheet is if you want to change your Y axis it only takes minutes.

[Robs455]

Wow, great info here and the new method IPW VS MAP is a huge improvement. I checked my old datalogs which was set with the MAP scale, the IEA is far way off as it should be with the IPW. Allan, why didn't you take the exact closing point of the intake valve?

I have software to calculate the intake air velocity, of course it's just theory, but it'll do for now. The air speed increases with the RPM, but also the crankshaft rotates faster and travels more degrees. Unfortunately, it shows the intake velocity speed based at WOT. I have absolute no clue what's happen to the air velocity in a (light) vacuum. The result of my setup is around 25° across the whole RPM band at WOT. But I'm sure with vacuum it would have less degree. I hope I can fine tune me setup on a chassis dyno.

[allan5oh]

Do you mean for WOT? That should just be done on a dyno. How do we figure out best IEA in the real world? Turning Closed Loop off at idle and watching AFR is one. Dynoing at various values and comparing HP values is another. I would think datalogging would be very tedious. It would be nice to figure out a method of bridging the rest of the table from the above two.

I'm really curious if Danny has tried this yet. He has probably spent the most hours fine tuning his engine out of anyone.

[95gts5oh]

Just wanted to provide some feedback. I just tried the tables you've posted. I noticed a huge improvement in off idle acceleration. I took the car for a quick spin and it was Learning at 7-10% in the cruise & acceleration areas vs my previous method. The fuel map has been dead on for a long time before this change. I'm guessing my IEA table was off by a long shot. Thanks!

[allan5oh]

Guys, just a note that you can use my Advanced Tables or at least the framework for them. But understand they were built for one specific engine with exhaust closing of 9° ATDC. Also, the top end isn't tuned at all. In order to do it on a dyno, I would just take the top half of the high RPM chart and move it around. Some people say their engine makes the most power at 0° or even positive. This is all a work in progress.
EDIT: If you're using Advanced Tables make SURE the Holley IEA table and the IEA Offset are 0. You can fine tune idle by moving the Offset around a bit.

[allan5oh]

If anyone wants, I can make a custom IEA map for them. I need your Global, and a datalog file would be nice as well. The more info I have the better. A well tuned IEA table is great. A dyno tuned one on the top end is even better. I also want exhaust valve close for my spreadsheet. Post your Global File with info. I hope Danny takes up my offer. EDIT: I would kindly ask for a before & after datalog. All sorts of driving.

[TBART1970]

If anyone wants, I can make a custom IEA map for them. I need your Global, and a datalog file would be nice as well. The more info I have the better. A well tuned IEA table is great. A dyno tuned one on the top end is even better. I also want exhaust valve close for my spreadsheet. Post your Global File with info. I hope Danny takes up my offer. EDIT: I would kindly ask for a before & after datalog. All sorts of driving.

I'm still trying to understand all of the informative info you guys have supplied, my brain is still hurts.
I was going to ask if you would be willing to do this. Thank you from the less computer literate.