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15 WRX FA20F DIT build with ATOMX


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Hi, Everyone

I am currently building my own project on 16 WRX FA20F DIT,and I am seeking  professional suggestions on my build


Ideally is to use ATOMX to control 4 Port injectors and FlexFuel to run sequential injections ,

(Atomx will work as piggyback to control AUX fuel only) 

Following are the input signals for ATOMX if my idea is workable

1. Crank trigger ( does Atomx support FA20F DIT trigger pattern?)

2. MAP

3. Water temp

4. IAT

5. FlexFuel

6. WBo2


kindly share your comments and suggestions

thank you

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Most of it should be ok. 

One thought I have is to do with sharing the temp sensors. On the Atom, the two temp inputs have fixed pull-up resistors (cant turn them off like our bigger ecus), so to share the factory temp sensors with the atom and OEM ecu you will need to connect the temp sensors to AN Volt inputs.  

But the Atom only has 3 AN V inputs and you would need 4.  One option would be to use a CAN bus wideband (spartan3 is a cheap option) which leaves you the 3 inputs for MAP, ECT & IAT.  Flex goes to a DI so that is fine.

The FA20 trigger pattern is supported as far as I know (at least BRZ etc is).  You will need cam sensor connected as well for sequential.

Does the stock ecu have flexibility to cover the extra flex fuel requirement at idle/cruise etc?  Because unless the port injectors are going to be tiny you wont be able to add just the small amount of extra fuel required to support flex at low rpm/loads.  Most injectors have a minimum PW that they will respond to somewhere around 1.5ms so you will only be able to turn the port injectors on at say half throttle or so.  

Another issue may be the OEM rpm/boost limits.  If these use fuel cuts but you are still injecting fuel with the port injectors things are going to go bad quick.

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Hi, Adam


Thanks for your prompt reply.

Understand , Now I will need to cross check if the BRZ/GT86 trigger pattern will  matching the DIT ,

OK, for sequential injection I will need both trigger signal from Crank and CAM, 

so does Atomx support the DIT CAM trigger pattern ?


The stock ecu will be flash over with ECUTEK and RUN speed density  ,yes it will be feeding FF signal (0-5V via TGV port )

for the boost and RPM cut will be adjust accordingly to the new setup! 

thank you.


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OK, just confirm that both BRZ and DIT has different trigger patterns.


36tooth 3gaps missing 2 tooth each


36tooth 2gaps , 

1st gap after 15tooth missing 3tooth, 

2nd gap after 16tooth missing 2tooth 

In this case how can I setup trigger in ATOMX?

Pls advise


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