Snake Eater Injectors 1500cc Tuning Help (No Control of AFR)

[CamaroCam]

Hey guys,

Im having issues tuning my new set of SEP 1500 injectors. After installing the 3 Bar Map sensor and injectors, I cant get control of the AFR. After entering the SEP excel data and tuning in SD, at idle, the afr reads 10.5 with 2.6ms pulsewidth. I tried lowering the min pw in increments all the way down to 0.106 and had no effect on the afr or pulsewidth. I changed the min pw back to .790 and lowered the VE in increments to values less than 10. The pulsewidth began to oscillate between 1.2 - 2.6 ms pulsewidth. I knew that was wrong so I then adjusted the transient to .002 and it idled at 18.5 afr with 2.0 ms pulsewidth. I then tried tuning the VE in increments and the values were high 70's in the idle cells. I knew that was wrong so I changed the transient to 0.028 and now it idles at 11.5 afr with 2.1 ms pulsewidth. I figured that was the fix but i decreased the VE by 20% with no effect (see log below). Ive tried multiple transient values ( .008, .020., .035, etc) but when i make changes to the VE, theres lil to no effect.

Since ive installed these injectors, the car's rpm jumps randomly and it doesnt like to start hot either. It still has the stock cam so i dont understand why the rpm jumps randomly or why it wont start hot. Ive been researching for weeks but cant figure out these issues. I really just want to drive my car again PLEASE HELP. Im knew to tuning so any advice is helpful.

Setup:
Stock LS1 internals
2000 p01 ecu
Huron Speed Turbo Kit
3 Bar Map Sensor
SEP 1500 injectors
Boost Ref Fuel Reg
Speed Density

[5FDP]

What the fuel pressure you are using and what does SEP set the flow rate data at?

Is it 3 bar or 4 bar pressure?

Normally chopping the min fuel milligrams in half does help a lot with the rich idle problems.

[CamaroCam]

Hey 5FDP,

Im a big fan and appreciate the help. My car is set at 4 bar (fuel regulator reads 60 psi). The SEP injectors came with a spreadsheet showing the lab results tested at 43.5 psi. I knew that data wouldnt work so I had them send me the excel data attached above. That shows the flowrate at 4 bar to be roughly 145 lb/hr.

[CamaroCam]

Could someone explain the necessary steps to tuning big injectors? Maybe i overlooked something simple. So far, Ive changed the flowrate, limits, offsets, pulse correction, and transient min fuel in milligrams. Are there other tables i should edit when jumping to 145 lb injectors?

[5FDP]

Lowering your fuel pressure may help. I would try 3 bar pressure and adjust the flow rate, see what it's like. You really don't need 58psi unless this thing is going to make 1000hp.

[Ben Charles]

Where you located??

[CamaroCam]

Ill try lowering the fuel pressure. I am located in the Chicago, IL area.

Also, im going to give this a try.

Go to Transient Fuel and reduce the Min Fuel milligrams from whatever it has to 0.014 and test. Bring it lower until you gain fuel control with the VE table.
The easy way to know is if you can enrich/enlean the AFR using either the VE table or scanner controls, you are in the ballpark. If you can't change the AFR then you need to lower it more.

I don't like to zero it, since it causes lean stumbles when you press the gas pedal. It can be compensated with VE table but I prefer to use the highest possible setting. For me it goes from 0.018 for 6.0L to 0.004 for 4.8 engines.

[Ben Charles]

Ah ok... I did a set not long ago that was a pain in the butt on a turbo 4th gen.. they ended running ok with a few hours of work

[CamaroCam]

Update.

I changed the VE table back to factory values and changed the transient to 0.027. It now idles around 15.0 afr!!! Feels good to finally making some progress but i noticed my O2 readings are way to far apart. B1 reads 235 mV and B2 reads 850 mV. Is that normal? The car is in SD but it was making some serious smoke like it was running pig rich.

[5FDP]

If it's open loop the o2 sensors will kinda just do what they want at idle.

Well your widebands shows fueling is steady so the smoke likely isn't from running rich.

[CamaroCam]

So after a weekend of tuning, I'm still having issues tuning my VE table. The problem is when I go to adjust my VE by a percentage, the resulting change is double. Example: If the AFR is 10% rich, I decrease the VE table by 10%. Then after starting the car and letting it idle, it will read 10% lean. I figured it was the transient fuel min value so i continued to decrease the value but it made no difference (decreased fuel min to 0.020). Also, after changing the transient fuel min to 0.027, I had to increase the VE table to high values. My idle cell values are in the mid 80's for an AFR of 14.7.

My question is are high values normal for a VE table using big injectors? Secondly, what are signs of wrong/bad injector data?

P.S. Ben Charles would you mind posting your tune file for the turbo 4th gen you tuned? It would be helpful to have something to compare mine too.

[99CamaroSS]

Ah ok... I did a set not long ago that was a pain in the butt on a turbo 4th gen.. they ended running ok with a few hours of work

Can you post your injector settings for this Ben?

[pdsq98gt]

I had a similar issue with the same injectors. I had to lower the fuel pressure to 43 to even get it to spray fuel on a hot restart. I?m not a huge fan of them but the price point is usually too good for people to resist. ID injectors are super easy compared to these. But $1000 is a hard sell to some people.

[blindsquirrel]

If you've built something that really truly needs injectors that big and can't afford another $1k... /smh