Hydra EMS Forums

[Ace83]

I have denso 550 injectors and I just found out that they have 2 ohm resistors.. I searched and found the injector lag as follows

Denso 550cc
2 ohm Injectors
1.24ms @ 10Volts
1.04ms @ 11Volts
0.87ms @ 12Volts
0.75ms @ 13Volts
0.64ms @ 14Volts
0.55ms @ 15Volts

http://injector-*.com/kbse/lag.htm


looking at the hydra settings, its way different from the 2 ohm Injector response values on the preset from the 2ohm values that i found.. I checked the 16 ohm setting on the hydra and the lag on my injectors are even longer.. Are the settings on the hydra based on low impendance injectors? Should I enter my own injector values or just choose the resistor setting that my injectors have

[MR Controls]

The injector response settings on the Hydra are intended to be an average starting point based on the manufacturer sheets from different injectors. No two injectors match even when they have similar impedance ratings.

I keep a 30-amp variable voltage MASTECH power supply at the shop to adjust the injector response curve. I find the fuse or fuses that supply power to the EFI system, pull them out and use my power supply to feed power to these circuits. I can then run the EFI system anywhere between 10 and 16 volts. I find the exact opening time by setting the injector reponse curve so that a 10% increase in the fuel map values produces exactly a 10% increase in AFR at the 13.6 volt point. Then, I adjust the rest of the injector response curve relative to the 13.6 volt point so that idle AFR stays rock steady as I adjust the voltage from 10 to 16 volts. I perform the injector response curve operation only after allowing the motor to idle for at least 30 minutes in a location whose ambient temperature stays relatively constant to eliminate the effects of temperature on fueling.

If this sounds like a lot of work, that's because it is. I do this on cars where I build a map for a known configuration that I will sell many copies of. Most of my customers cannot afford the setup and tuning time to get a perfect injector response calibration, so they get a quick verification of the proper response setting at their normal charging voltage with a reasonable "guestimated" curve above and below this point. Not perfect, but good enough for most purposes.
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[Ace83]

wow that sounds a lot of work.. thats seems to be a very reliable method though.. Im gonna leave my setting to 16ohm since im tuned at that setting and it seems to work fine so far..I was just curious how likely i would need to adjust those setting if i decide to change my injectors.. thanks for the info

[Ace83]

I just got new injectors here, as i adjust the fuel map by %.. the afrs changes between boost and vacuum is kinda different, too rich on boost and a bit lean on vacuum.. I was thinking it might have been my injector impendance and lag changed.

now i got the specs, injector response is at 16ohms, but as i increase the ms it would only go up to 1.275? any ideas? I have hydra 2.5 on an 06 scion tc


here's my injector specs

[MR Controls]

The chart shows offset decreasing as the differential pressure goes from 55 to 60 psi. Injectors don't work that way. Higher differential pressure always increases offset since the coil has to work harder to push against the pressure.
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[Ace83]

hmm, i might need to verify that info with the vendor. It may not be accurate from one differential pressure to another but im more concerned on the ms vs. voltage.. I could only go up to 1.275 max, if those specs are accurate then i can only setup my injector at 14v and 15v?

[Ace83]

also if injector resistance is 12-12.5 ohms, should the setting be on 8 or 16 ohms coz it falls somewhere in between..

one tuner once told me an ecu set to run low impendance injectors can run high impendance but an ecu that runs high impendance injectors will get damaged if low imp injectors are used? not sure if that is true with the hydra but 8ohms setting will be much safer for a 12ohm injectors?

[MR Controls]

The setting you select does nothing excpt to populate the injector response map. The hardware is not changed, altered, rewired or affected in any way. The injector drivers are peak and hold and as such cannot be damaged in any way with either high or low impedance injectors since they sense exactly how much current they need to put out.

Even if you don't have good adjustable voltage supply to properly calibrate the injectors yourself, you can set up the auxiliary map to add exactly 10% to the injector pulse width (so where you have 1.00ms in the base fuel map, put in 0.10ms in the auxiliary table). You only need to do this in the 16-20 or so cells where the engine idles when warm. Then, set up a switch to switch the auxiliary map in and out. You should then adjust the injector response value for the voltage that your system is idling at so that you get exactly a 10% AFR increase as you make the switch (for example, 14.7/1.10 should give you 13.4). If you get more or less, adjust the injector response curve appropriately until the switch yields a perfect 10% change in AFR. You can then unplug your alternator and make a second calibration at the lower voltage. The two points should give you a very good idea of what the injector response is really like on your setup.
_________________
http://www.mrcontrols.com

[Ace83]

you mean the "ohms setting" is just like to load a default value from hydra as baseline? i got what you mean now..

So on the hydra, the max ms on injector response map is only 1.275 or that can be adjusted?

[MR Controls]

Max injector offset on the pre-2.7 systems is 1.275ms. That has always been enough although lately there have been some large, high impedance injectors offered on the market that may have longer offsets. I prefer to go with a low impedance injector on the Hydra. You paid for the fancy peak-and-hold injector drivers, so you may as well get the benefits of low-impedance coils.
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