AEM AEM AND ADDITIONAL INJECTORS

[erikoberdorfer]

Hello,
I am planning on wiring up an additional set of injectors on my 92 awd dsm. I currently have a set of FIC 2150cc injectors in the car, but am running out of fuel at high boost. My plan is to likely run a set of 1100cc high impedence FIC injectors mounted to my magnus intake manifold using their secondary rail kit. I use an aem series 1 ems to tune with. My question is, has anyone else done this and how did you do it? I think I can just mount the rail (weld) to the manifold, install the injectors and run the fuel lines. Then, wire the injectors from the aem (high z because I already deleted the resistor pack), and "turn them on" in the aem? Phasing them in seems to be a choice between several methods on how to do it? Any experience or advice is appreciated.

Thanks,
Erik

 

[erikoberdorfer]

I was able to get this project done. I installed (welded) a Magnus secondary injector rail / mount to my Magnus v3 intake manifold. I purchased a set of FIC 1100cc injectors (high z) and mounted them onto the secondary rail. To supply fuel I utilized a -10an line off of my Aeromotive fuel filter and used a 10/10/10an y block. From each "branch" of the y block I ran a short -10an line to the "feed" side of each fuel rail. From the ends of each rail I used a -8an line that feeds each side of my Aeromotive fuel pressure regulator.

To start, I left the fic 2150cc injectors in place as the primary units. The secondary injectors utilize a custom wiring harness I built from old OEM dsm wiring harness parts. To wire it I ran one wire to one terminal of each injector and connected that to the spare injector driver outputs on my series 1 aem. These were pins, 77, 78, 79, and 80. The other terminal of each injector was wired to a switched 12v power source. In my case, I tied into the existing switched 12v MPI supply voltage (pin 102 on the aem). The 12v switched portion of the wiring is all tied together so that all injectors receive 12v from the same source. Aem requires a special additional ecu plug for this ecu that I had already purchased for enabling me to datalog fuel pressure. I simply pinned the ends of each injector (5,6,7, and 8) and plugged them into the pins on the ecu (77 thru 80).

To get the aem to work with the injectors, I did the following.

1.) Options: injector- I selected 1 thru 4 as "primary".

2.) Options: injector - I selected 5 thru 8 as secondary.

3.) Options: staged flow ratio- I calculated the stage flow ratio of the primary vs. secondary injectors. This was accomplished using the following formula:
Staged Flow Ratio = ((number of primary injectors x primary flow rate) / (number of
secondary injectors x secondary flow rate) x 100) - 100
In my case this turned out to be 95.5

4.) Options: Inject tooth, I matched the inject tooth for cyls 5,6,7,8 to the values of 1,2,3,4.

5.) Battery offset table: I defined the secondary injectors as per the data sheet supplied by FIC.

6.) Options: injector duty max. I set this to 90%. This means the primary injectors (2150s) go to 90% duty cycle and wont go above that value.

7.) Options: injector min: I set this value to 0, but I may have to play with this. I think this sort of acts as a delay for the primary vs. secondary injector activation.

Testing:
Once I determined I didn't have any fuel leaks I decided to test this out. I started the car with the modified / loaded aem cal. Then once at operating temperature, I set the injector duty max to 1%. I then was able to pull up parameters and watch "inj duty primary" and "inj duty secondary" in the window for aem. When giving the car a small amount of throttle I noticed the primary injectors stay at 1% and the secondary duty cycle jump up. The car still ran but the response was a bit rough. I verified that the secondary injectors were firing under the hood.

Finally, I set injector duty max back to 90% and went for a drive. I setup aem internal logging to capture the primary and secondary injector duty cycles.
With the boost turned down I tested it all out. I found that the setup worked quite well. The primary duty cycles hit 90% and then the secondaries ramped in quite smoothly. In the datalog you could see that the primary duty cycle now limits itself to 90% and a secondary duty cycle graph ramps in. My o2 sensor readings remained stable and the car felt great. There are other ways that the secondaries can be activated, but this is working well so far. I have only started working with this setup, but so far it is showing promise.

I plan to raise the boost and tune it in the coming time. I hope that this write up will help anyone out there wondering how to do this.

Thanks,
Erik

 

[camocorvette]

This is what I was looking for!
I'm a ways off from tackling this. But I wanted to do the research. I have 1250s and thinking of adding probably 880s or similar. I'll be running e85 and most likely 6062-6466 precision turbo. My main reason/thought for this is I dont want my IDC's maxed out. Also in my understanding I could run the 880s as primary for street driving and idle.

 

[bastarddsm]

Something I would reccomend, is try and make the primary similar in size to the secondary. Say you have one set way smaller than the others, and a small one fails, it's possible to go just a little lean and burn it up. but if they are both similar sizes, and the small one fails, it will likely go so lean it won't even fire.