Injector scaling vs load

[3gturbo]

I need some help figuring out the injector scaling heres the problem. I have a 03 eclipse Manual tranny it has 240cc injectors stock I added 550cc f.i.c. injectors and I tried to flash the ecu to idle with the new injectors. Well when I change the injector setting it also changes what the car sees for load. For example with the stock 232 setting for the injectors it idles at 15% load. With a 430cc injector setting it idles at 25% load and I can hit 60%load just by revving the engine slightly. I took the car around the block and it hits 80% bload by 2k rpms. Anyone have any insight as to why the injector setting changed the load percentages so much? Any help is much appreciated.

[zlancerman]

This is interesting to see since I'll be doing something similar next month (going from 240cc to 440cc). Someone told me that the injector scaling should go opposite, meaning the larger the replacement injector, the smaller the number you should enter. This is due to the fact that the car is meant to idle with the stock injectors. When you double your injector size, you also double the amount of gas that enters the engine under the same pulse width since the car thinks its the stock injector. To compensate for that, you cut the scaling factor in half. So theoretically, if you double your injector size, you should half the injector scaling number. Try that out and see what happens. So set your injector scaling factor to say 115 or 110. Let us know what happens.

[m3n0ch3]

Guys,

don't you have a 1D map in your Mitsu to indicate the size of the injectors?

In subarus, you just have to switch from a 380 to a 550 injector size and the car idles normally. I doubt mitsu wouldn't do the same....

[3gturbo]

This is interesting to see since I'll be doing something similar next month (going from 240cc to 440cc). Someone told me that the injector scaling should go opposite, meaning the larger the replacement injector, the smaller the number you should enter. This is due to the fact that the car is meant to idle with the stock injectors. When you double your injector size, you also double the amount of gas that enters the engine under the same pulse width since the car thinks its the stock injector. To compensate for that, you cut the scaling factor in half. So theoretically, if you double your injector size, you should half the injector scaling number. Try that out and see what happens. So set your injector scaling factor to say 115 or 110. Let us know what happens.

Very interesting indeed I'll try messing around with it and see what I can find out.

[Freon]

Well, since the ECUs are so similar...

For all Subarus, both DBW and older models, the actual data value stored in the ECU is scaled inversely from injector size. Think of it more like "length of injection time to match X grams of air for stoic combustion" or something. So a larger injector takes less injection time, needing a lower number.

However, you can setup the XMLs to invert it back for you in your editor, so you can punch a number in that is close to the actual cc/min or lbs/min of your injectors. But the NATIVE data is injection period adjustment. Higher number means smaller injectors, and vice versa.

It definitely should not affect load! This isn't a MAF piggyback. I'd say something else is at play here. Keep in mind changing your injector scaling could have indirect consequences.

When swapping injectors, you should change nothing else, but especially the intake. Put the injectors in, adjust both your dead time and injector scaling while the car is stationary. What I do is adjust the injector scaling just before the first startup to what should be close (i.e. adjust by percentage change. Double injector size? halve the value, 40% larger? divide value by 1.40, etc). Then check idle AFR and correction, and rev it up a bit and see how it trends. If it idles way lean, but when you slowly rev it up to 3500 it goes back to 14.7 and low trims, increase your dead time. If it is rich all the time or very negative fuel trims, adjust injector scaling. Log your AFR, AFR trims (ST and LT, but mainly ST since we're just starting it up briefly), and injector pulse.

[repforenzo]

This is interesting to see since I'll be doing something similar next month (going from 240cc to 440cc). Someone told me that the injector scaling should go opposite, meaning the larger the replacement injector, the smaller the number you should enter. This is due to the fact that the car is meant to idle with the stock injectors. When you double your injector size, you also double the amount of gas that enters the engine under the same pulse width since the car thinks its the stock injector. To compensate for that, you cut the scaling factor in half. So theoretically, if you double your injector size, you should half the injector scaling number. Try that out and see what happens. So set your injector scaling factor to say 115 or 110. Let us know what happens.

I’m not sure I would agree with that. I have the 3.0 L v-6 and I used the ECU Flash to tune. I recently replaced my 210cc injectors with larger 310cc and initially scaled them in the flash as '310'.

don't you have a 1D map in your Mitsu to indicate the size of the injectors?

Yes, we have that 1D map. Even though, I don't think it is a perfect one-to-one ratio with the cc size of the injector, I believe that number has got to be close.

When I put the number '310' in, the car idled fine, but my long-term fuel trim were way positive during idle. With my 210cc injectors, I was always a bit negative. So, why would the ECU need to add fuel for larger injectors? Because the scaling, the way I believe it works, is doing its job. It is narrowing the pulse width of the larger injectors to the point where I had positive LTFTs. I change the scaling number to "305" and my LTFT got better. I'm now going to try "295" and see how that lands.

Guys, I can't say I know for sure... and this thread has made my wonder if I scaled the injectors properly... but to scale 550cc injectors to a number of '120', doesn't make sense. I just recall before us 3g eclipse owners had the flash, there were a lot of attempt to prevent the idle from getting too rich during idle (the injector scale on our car was still 220 and people were put the 310 and the 440 injectors on).

3gturbo, I'd try to make incremental changes like go to '530' or '520' and see how you load and LTFTs work out. I’m still learning myself and let me know if my thought process is incorrect.

[thefranchise]

injector scaling and accel enrichment go hand-in-hand. you'll need to dial the accel enrichment back with larger injectors a tad. i dont have a good rule of thumb yet though

[repforenzo]

injector scaling and accel enrichment go hand-in-hand. you'll need to dial the accel enrichment back with larger injectors a tad. i dont have a good rule of thumb yet though

Yeah, I noticed that also... the multiplier affect is greater with bigger injectors... and I tend to go a little too rich when I first hit it...

But that is not what this thread is about... what do you feel about the initial setting of the injector scaling? That field is not a multiplier from what I understand...