I have the Greddy/Denso 720's and I am having a really hard time getting my injectors sized. I used 542 for the size and I keep adjusting the latency, but the car doesnt stay stable. It will idle fine for a while and then all of a sudden it will get rough and want to stall. It will run pretty good at cruising speeds, but it wants to stall when I let off the gas and it pulls timimg really bad when you give it a lot of throttle.

Who else has used these injectors and got them sized so the car can run smooth. Could you please post your settings so I can stop pulling out the little bit of hair I have.

 

set scaling to ~660 cc. I think you need to add roughly 400 ms to all the stock latency number if I remember correctly. The denso 720cc injectors have a pretty long dead time. Because the deadtime is so long, the car will run lean at idle, if you use to low of a deadtime value, that is why your idle is screwy.

Brian

 

Thanks I will give it a try. I will try it again today.

 

Report back and let us know.

The Evo I auto-x runs 720's and has runs very smooth most of the time, but has known to stall after a hard run or sometimes coming to a stop light, but most often at the end of a hard pull if the throttle is cut and the clutch is engaged it has a hard time staying alive for a few seconds.

2003 Evo w/272 cams, 720cc injectors, FMIC, UICP, 3" TBE

Injector scaling
513

Injector Battery Voltage Latency Compensation
4.69 - 3.312
7.03 - 1.680
9.38 - 1.032
11.72 - 0.672
14.06 - 0.432
16.41 - 0.264
18.68 - 0.144

 

I can tell you 513 is not right for denso 720cc injectors. Think 100 more at least.

 

Yea we're going to bump that up to 600 or so in the next few days. Gotta run some logs on the car and see if our dead spot around 5500-6000 is related to the new boost creep anyway

 

Well didnt get a chance tonight to test it out I have a map written I just have to load it up and test it in the morning. I am taking the day off work so maybe I can figure it out. If not I ordered a set of 780's from Buschur. I know my friend had his car with 272's and 780's tuned with an AFC idling smooth as a babies butt. One way or another I will get it figured out. I'll keep you guys posted and thanks for the help and support. Can I have a hug?

 

Well after numerous different configurations I found out that for the 720's I needed to do. I sized the injectors at 636 and for the voltage latency I just multiplied the whole table by 2.2. The car idles fine and it even idles with the A/C on, which hasn't hapened in a long time. I also bumped up the idle 100 rpm. So far all the logging I have done has had the fuel trims +10-10. I still have some more logging to do to make sure the fuel trims stay steady.

 

636 is indeed correct.

 

Now you tell me. j/k

 

Glad you got it working. Did your Voltage Latency table look like my post above above before you modified it? (I don't have a stock 03 map to base it off of).. Post up your Injector Latency #'s if you can

 

Stew your numbers above are stock.

 

Good to know

 

I have some information.
Japanease guys give this to me long time ago.


DENSO, SARD, GREDDY, HKS injector parts no.195500-0830

impedance 2.3 ohm

pressure (kg/cm2) / volume (cc)
2.55 / 680
3.05 / 750
3.55 / 820

injector dead time 0.96ms @ 3.05 kg/cm2 , 14.0 volts

 

Really old thread but Im curious about the information posted. What is the latency of the stock Evo VIII 560's? Im having a tough time tuning my G-VR4 after switching from 560's to these -0830 Denso 720's. I have no way to compensate for latency at the moment. Im running an EVO 8 MAS w/AFC if that helps.

Does anyone have any experience tuning these injectors using dinosaur technology such as an AFC?