Scaling Injectors 09 E38 ECM

[HartsG8GT]

In preparation for my supercharger install, the install of 75 lb/hr injectors, and the ECM limit of 63.5 lb/hr injectors I thought I would mess around with scaling the stock injectors to see what happens. To make it easy I just divided the stock values in half and then changed the values in the "flow rate vs voltage" table to multiply the flow rate by 2 for all voltages. By doing it this way I assumed that I wouldn't have to change every table that involves airflow. Below is the only tables changed.

Like this


I went out and did some data logging afterwards and all seems to work just as before, AFR is still spot on. What do you guys think? Any downsides to tuning for bigger injectors this way? Sure would make life easier. I'm just not sure if when I install the 75 lb/hr injectors and adjust the tune like this if it will get past the coded limit of 63.5 lb/hr.

[gn2beatu]

Very interesting.......goona follow this thread. What about all the other multiplier tables, and timing tables, did you leave all them the same (unmodified also)? I have never heard of doing it like this before. Maybe you discovered a new way to scale....hmmm.

G/L with this, and keep us posted!!

[DSteck]

Flow rate after the modifiers is clamped at 63.5 lb/hr.

[IDRIVEAG8GT]

Great idea, but I just don't think that that is going to work. As mentioned above, flow rate won't go above 63.5 lb/hr. If that wasn't hard coded well hell, it'd be easy.

[HartsG8GT]

Flow rate after the modifiers is clamped at 63.5 lb/hr.

Dammit thats what I figured. I am pissed now cause I checked an 09.5 G8 tune and they have the 127 lb/hr limit. Scaling the tune is a major pain in the ass isn't it? I have read DStecks guide but I have to admit I'm still confused. Can I modify all of the airflow tables suck as in the spark table below by taking the airmass axis and dividing the table in half. Like this:

[DSteck]

If you can edit the axis, that's the easiest way to do it.

[HartsG8GT]

Thanks a lot. I am in the process of scaling my tune right now. Do you mind taking a look at the before and after when I'm done to make sure I'm on the right track and not changing tables that don't need to be changed?

[DSteck]

Just make your life easy and double the stoich AFR. Don't bother scaling all that other crap. Cut IFR in half, double stoich, done.

[HartsG8GT]

Well damn thats easy. No downsides to doing it this way?

[DSteck]

Your commanded AFR shows up as twice the value but just use lambda and it becomes a non issue.

[HartsG8GT]

Thanks DSteck.

[IDRIVEAG8GT]

Dammit thats what I figured. I am pissed now cause I checked an 09.5 G8 tune and they have the 127 lb/hr limit. Scaling the tune is a major pain in the ass isn't it? I have read DStecks guide but I have to admit I'm still confused. Can I modify all of the airflow tables suck as in the spark table below by taking the airmass axis and dividing the table in half. Like this:

Even though the IFR carries higher, we're still screwed because Cyl Airmass/Timing calculations quit at 1.36g/Cyl, therefore, you run out of spark table, even with that big injector cap.

[SargeZ06]

Your commanded AFR shows up as twice the value but just use lambda and it becomes a non issue.

Or just create a custom PID "True Commanded AFR" - Commanded AFR * .5?

[DSteck]

Or just create a custom PID "True Commanded AFR" - Commanded AFR * .5?

Meh. I prefer lambda anyway. Then I'm not mucking with the stoich point for the wideband every time I tune a different car. Gas, E85, unicorn blood... It all plays out the same with lambda!

[SargeZ06]

No I agree but you brought up Commanded AFR being double so I just gave a fix for that. Commanded Lambda is not affected.

[HartsG8GT]

Even though the IFR carries higher, we're still screwed because Cyl Airmass/Timing calculations quit at 1.36g/Cyl, therefore, you run out of spark table, even with that big injector cap.

That's another question I've been meaning to ask, how do you tune spark advance once you pass the 1.36g/cyl cap?

[gn2beatu]

It just uses the last value from the end of the table.

[Yasei]

Just make your life easy and double the stoich AFR. Don't bother scaling all that other crap. Cut IFR in half, double stoich, done.

Are you using this method succesfully in your Z06 (E38)?

Anyone know if this works in e40 as well?

[IDRIVEAG8GT]

That's another question I've been meaning to ask, how do you tune spark advance once you pass the 1.36g/cyl cap?

You have two options:

You can either change the axis label in the spark table, or the most logical way,

When you scale the tune 50% you reset the timing tables.

What I mean by that is that the duplicate of g/Cyl Airmass rows will be moved up into it's 2nd divisible. Anotherwords, the .16 g/Cyl row will be copied and pasted into the .08g/Cyl row, and the .32g/Cyl will be copied and pasted into the .16g/Cyl row. Do that until you finish the table, then you can simply clean up the unfinished section of the table with numbers that follow suite.

[DSteck]

Are you using this method succesfully in your Z06 (E38)?

Anyone know if this works in e40 as well?

I'm using it in my Z06 with the custom OS for the increased airflow limit.

It won't work on an E40 PCM if you move more than 67.7 lb/min of air.