Ceddy

Hello,

I had a question how the Injector Scaling formula was figured out?
EcuFlash has 29241/x. Is 29241 a fundamental number somehow? Or found in the ECUs code?

It seems like everyone enters numbers way smaller than the injectors measured flowrate.


In the DSM world we use the formula 31050/x. This gives a number that is spot on the actual measured flowrate with aftermarket injectors.

Example:
EVO 8 USM 0x39=57, 29241/57=513cc, 31050/57=545cc
EVO 6 TME 0x36=54, 29241/54=542cc, 31050/54=575cc
DSM 95-99 0x45=69, 29241/69=424cc, 31050/69=450cc


Does anyone know where 29241 came from?


Thanks very much for any info.

acamus

Unfortunately I do not know the answer to your question.
I am thinking your number is more accurate, but I have the same
question for 31050... Where does it come from?

Ceddy

Unfortunately, I think it was found by:
0x45 = 69 x 450cc = 31050

I can't find any constant near that size.
31250 would be a divisor of clock freq, like how we have 15625 baud for logging.
But I don't think thats applicable.

I thought the Evo8 injectors flowed 560cc.
0x39 = 57 x 560cc = 31920

29241 seems way to small.

Biggy VIII

Great!

After many attempts to scale my PTE780's correctly I stopped at 713. Now that explains why 713 works best for me!

29241/41=713cc, 31920/41=779cc


Any info about latency?

rolly1818

the JDM Evos (7-9) are scaled to 542cc which is pretty close if you use 31050

however where do you get the 0x39=57 piece? that has me a little confused.....

Ceddy

0x39 is the hex value for injector size from the flash image. 57 is 0x39 in decimal.

57 base 10 = 39 base 16

rolly1818

Thanks, sounds interesting.

the AUDM and JDM are both 542cc/min stock. any feedback on this?

our injector latencies are slightly different as well.

merlin.oz

This is an interesting thread, so I did a hex search on my AUDM9 rom for the three factors mentioned.
29241, no hits.
31920, no hits.
31050, multiple hits.
So, if 31050 (hex 794A) is not just a bit of op-code, it looks like it may be the correct scaling.
Over to the dis-assembles now I think.

GRNCT9A

iTrader: (1)

this is very interesting. So my pte680cc injectors should be scaled at 622. Whats more interesting is that you can actually put that number in.

Now I gotta figure out a formula for lat.

cossie1

What latency's did you use for the PTE780's ?

JDMEvo9RS

I don't think there is any mathematical formula as each injector manufacturer has different results.

rolly1818

damn wish it was not this difficult lol....

Ceddy

Aftermarket manufacturers often overrate their injectors, but actual flow rate can be measured by having your injectors flow tested.

OEM injectors are most always dead on.

I'm not talking about advertised flow, but actual measured flow at 43.5 psi base fuel pressure.

There is definitely a scaling formula, all I am saying is 31050/x seems more accurate then 29241/x.

the_mork

iTrader: (1)

I always thought the difference was largely based on the evos having a lower fuel pressure of 38psi IIRC. I could easily be wrong though.

This is why my DSM with evo8 injectors is scaled to 545, not that it didn't run beautifully at 513, but my fuel trims seem better at 545. Until I read about the difference in fuel pressure I always just assumed I had a boost leak.

Biggy VIII

0.744 @ 14.6V

I cant remember other latency's. I can check them if u want.