Semi sequential fuel with distributor

[Chris77]

Atom ecu , chevy v8 with Holley dual sensor distributor and 8 fuel injectors .

 

Installing the atom in a friends vehicle and he still wants to run the distributor for ignition , at some stage me may go to a wasted spark setup . To run in distributor mode I understand the secondary sensor of the dist will have to go to trig one , ie the 8 tooth signal . My two issues is I would like to wire up the two sensor inputs , one is a single tooth tdc and the other the 8 tooth spark . If  I use both sensors I believe the tdc trigger has to go in trig one ? Is there any way to set the ecu up to receive the tdc input and then fire the same ignition signal out ?

Two reasons for this , one if he upgrades to wasted spark the wiring is already there and , two , could I then utilize the semi sequential fuel control . Tied with this for fuel control in mutli fire can it still use the 4 outputs , ie can I wire up the injectors now as per the semi sequential diagram and run multi injection with the 4 injection putputs , or under mutli will it only run 2 injection outputs . 

 

Sorry as you can tell I am not familiar with the link ecus and would like to get it future proofed for him if I can , so any input would be helpful

Thanks

Chris

Edited March 14, 2018 by Chris77
Spelling

[ClintBHP]

Both the Ignition and Fuelling Strategies are independent of triggers, you just need 'enough' triggers for the strategy you need to run.

The Holley Dual Sensor dizzy, gives you 1 pulse per fire for Crank and Single Pulse for Cam.

So Trig1 = Crank and Trig 2 = Cam 

With this setup you can run both Distributor and Wasted Spark Ignition and Multi Point Grouped for Injection.

[Chris77]

Ok , so I am looking at this backwards . Trig one wants to be the 8 tooth and trig 2 is the single tooth and select cam 1x . So thats easy I can wire both and  only set up the 8 tooth . Great . And reading the manual again it implies using all injector drivers unless too have too many injectors .

Thanks

Chris

[Adamw]

4 hours ago, Chris77 said:

ie can I wire up the injectors now as per the semi sequential diagram and run multi injection with the 4 injection putputs , or under mutli will it only run 2 injection outputs . 

 

3 hours ago, Chris77 said:

And reading the manual again it implies using all injector drivers unless too have too many injectors .

1

 

You can wire/pair the injectors as per the semi-seq instructions regardless of whether you went semi-seq or multigroup.  It can be set to use two or 4 drivers when in multigroup mode.

[Ken Dunkley]

Just to give you another option with your injector pairing - As opposed to the link instructions . With the distributor its easy to get the semi sequential as good as it can be . IE every second injector of the pair is only 90degrees out . So the way i did it ( remember not technically as per the manual) Is wire the injectors - Injector 1 - 1&8 .  Injector 2 - 4&3 . Injector 3 - 6&5 . Injector 4 - 7&2 .  Then input the firing order 15263748 . The ecu will then evenly space the injection events . Just wire the HT leads on the dizzy as normal . It just made sense to me to not leave fuel puddling in the port any longer than need be .  

[Chris77]

Ken , I dont understand the pairing you mention . Drawing it out the link pairs each 2 but one , so many 180 deg out . The pattern you give with the firing order you say puts two the same as the link but the other two , one is next (90deg ?) and the other is 3rd after .

However your pairing with the link firing order pairs each injector . Will have to sit down and work out the alt firing order , I deal with 4 cyl , I need to hands to work with 8 cyl .

Thanks for the replys

Cheers

Chris

inj pairs.pdf

[Adamw]

Note if you are only ever going to stick with the distributor, then Ken's suggestion would work well.  If you want to be able to upgrade to wasted spark later without a lot of head scratching then you would be better to stick to the method suggested in the help file.

[Ken Dunkley]

Chris - The pairing follows the correct firing order 18436572 .  The injector drive 1 is wired to cylinders 1&8 . Drive number 2 is wired to 4&3 . And so on .  If you enter the firing order i suggested injector drive 1 will fire first - injecting fuel in ports 1&8 . Cylinder 1 receives the fuel at the correct time - cylinder 8 gets its fuel 90 crank degrees early . The ecu ignores the number 5 in the weird firing order and moves on to drive number 2 . Which injects fuel for cylinder 4 at the correct time and cylinder 3 - 90 crank degrees early . And on it goes . With the input firing order of 15263748 the ecu ( Atom G4+ ) only sees the 1234 and because  theyre evenly spaced you get well timed semi sequential . The distributor leads still are wired and go to the plugs in the true order 18436572 . As it receives 8 signals to fire per 720 degrees it " distributes " the sparks to the correct plugs . Ive read this a couple of times so i hope it makes sense to you  

[Adamw]

2 hours ago, Ken Dunkley said:

Cylinder 1 receives the fuel at the correct time - cylinder 8 gets its fuel 90 crank degrees early .

Note the idea with semi-sequential is normally to "split the difference", so rather than squirting one cylinder at the ideal time and one 90deg early, you will find best performance/economy roughly when one is about 45deg earlier than normal ideal sequential timing and the other is 45 deg late.