Sequential Fuel injection
 

What's the advantage of sequential injection versus the standard?
I did a search but didn't come up with much.
I'm planning on builing a MS and I'm not sure if I should go with the sequential add-on or not.
I could see how it could help gas mileage in theory, anyone out there who wen to sequential injection?
Any gains?

Gunter

better efficiency, injection timing, idle smoother, idle smoother with larger injectors, better enrichment, better throttle response.

Possibly slower starting because it takes 4 cycles before all cylinders get fuel.

?

Should only take 1 cycle (two crank rotations) before all cyls get fuel, and another .25 cycle after that before all cylinders have gotten both fuel and a spark. Exactly the same as stock.

they are working on adding in batch fire when cranking on certain trigger wheels. i didnt really notice a change.

mines *marginally* slower, but honestly who gives a crap if it cranks for 1/2 a second longer?

Just means more time for the oil to get to the head ;)

My 2002 is all stock ignition and in looking through all the options inmy brand new MS from Reverent i noticed this screen:


http://www.diyautotune.com/images/te...tings_page.jpg


I am very new to all the possible parameters that I can manually change but I'm pretty sure I need to turn that to Untimed correct ? My noob understanding tells me this is for when you have COPS ?? Or am I way off here ?

seq. should be timed.

I was way off.


Embed fail so here :

How does non sequential injection work?

Fuel just sprays into all cylinders every single rotation???

like the 90-93. 1 & 3 and 2 & 4 squirt in pairs. twice per cycle.

It sucked balls when I tried it back in '06 with the MS1. Sequential is bliss.

having run batch injection on my miata since 1995, I can say seq. IS bliss.

Insert background harp melody for emphasis.

i should also take less gas?

its more efficient, yes. playing with injection timing (spraying the fuel based on crank angle and load/rpm) can improve it even more so. So you're only injecting once per cycle and you can time it so all the fuel is where it want it when the intake cycle starts.

Scott how does one go about tuning sequntial fuel injection timing? Get on a dyno and just bump it around and see what makes power?

I don't even know if my hydra can time the squirts.

There are a few ways to do it, but I'll discuss what I know.

I use end-of-squirt timing, which means that the angle I enter represents the crank degree where is fuel is finished squirting.

There is a rule of thumb that says you want to aim for 5-10° before the intake valve open, so the fuel not only cools off the valve, its all there and gets pulled in when the valve opens and piston lowers.

so my cam opens my intake valve at 5°BTDC, so at idle I aim for -375° crank angle ( which comes out to 15° BTDC).

Now since the crank moves so much faster with increased RPMs and the injector can only open/close so fast, we try to inject the fuel a little earlier to factor in some latency and dead time. I think I inject 10° earlier every 500RPM. Something like that. Also doing the same as boost increases.

Then I tuned my fuel map until there were no more major changes. This is very important.

So now with your current fuel map, you need to pick an area where you'd like to experiment with; maybe retard the injection timing a little more and see if you need to add or subtract fuel. If you need to add, then it's not the ideal angle for that load/rpm. So then you need to go back to your original fuel map and try advancing that injection timing in that area instead.

When you start pulling fuel that injection angle is the ideal; basically you can achieve the same AFR with less fuel being injected because you found the most efficient angle to inject the fuel at that particular load/rpm area, less pooling and better atomization.

This will take a lot of time and patience, but in the end you should be able to achieve better MPG.

Also note, depending on the size of your injectors once you get to a certain DC% there's no real benefit, maybe around 75%, it'll pretty much be injecting the entire cycle that the intake valve is closed, so there's nothing you can do at that point.

Very interesting. Makes sense. Niftayy

The hydra does actually have injection timing. It's a 2D table with # of degrees before BDC on the intake stroke that injection should end. Here's a pic of the table.

Attachment 241242

Stories of Man/Boy Love?

OT, sorry : Braineack, have you read my PM? I have problems and and your help would be essential

^lmao @man/boy love.

Another advantage would be that you can run low impedance injectors without needing resistors?

for seq. injection? not necessarily.

I thought you could only run one low impedance injector from each injector driver with the MS unless you use resistors in series with them?

No thats a hardware limitation, nothing to do with how many times and at what point the injectors fire, which is what sequential is all about.

To run low impedance injectors without dropping resistors, you just need an injector driver capable of PWM.

You can have sentential with or without low impedance injectors if you want. The two are not mutually exclusive.

its more about the power draw and grounding than anything else.

you can run low ohm injectors in batch.

OK, I was thinking in terms of it being an advantage of doing the sequential mod for MS specifically, but then I made the mistake of thinking this was posted in the MS specific forum too.

This is getting a bit off topic, but are you suggesting that I could run two low ohm injectors per injector driver on my MS2 DIYPNP without resistors? because my understanding was that that would require the injector drivers to sink more current than they can handle.

I don't think the uS card can handle 2 paired low impedance injectors.

The V3/3.57 with a MSI/II/III card can however.

Similarly the MS3X card can't handle low impendance injectors.

You could if you ran the P&H board. But running PWM drivers directly off the uS module will result in ground noise and flyback issues.

A customer of mine run low impedance injectors on the DIYPNP for several months, without knowing. He always had problems with the USB to serial converter randomly disconnecting from the PC. At some point he did burn one of them, so we found out and replaced the injectors.

Great thread. Can someone post pics of the sequential fuel menus in MSII and what they should be? I want to do this on both cars soon.

Thanks. Is it a good idea to upgrade to really large and or EV14 injectors over my 550RX7 injectors? Will a shorter injector opening time benefit me in any way?



You entered 375* to account for your 10% cam opening...is this back-timed or is the ECM counting 375* of rotation?

(Posting from my phone.)

You want larger injectors to keep. The duty cycle below 80% to be able touse the timing tables properly.

More like 60% DC

At WOT it's pretty unnecessary, it's quite helpful for economy at part throttle though.

Honestly if you don't have any issues currently with your injectors, then leave them. If however you're hankering after more headroom and a much improved idle quality at stoich, then hell yes upgrade.

First of all, i want to apologize for bringing this thread back from the grave but it seemed to have the best information about sequential injection which is relevant to my case..

So, i'm running a '91 miata with MS2 extra (by reverant). I thought i'd reconfigure the batch injection into sequential, but it did not quite go as planned..

So, i rewired the injectors according to Dimitris's instructions:

- Pin 1 (INJA) goes to cylinder 1
- Pin 2 (INJD) goes to cylinder 2
- Pin 3 (INJB) goes to cylinder 3
- Pin 4 (INJC) goes to cylinder 4

- Switch from "standard drivers" to "additional drivers" in megasquirt

Then i checked (and double checked) that each injector is only connected to the corresponding pin in the right order.

Now, the car would not start up. It fires after cranking and dies immeadiately afterwards. I did manage to get it run (barely) by pushing throttle. This caused the engine to run very lean. As soon as i release the throttle, the engine stalls.

Now, if i change back to "standard drivers" the engine runs just fine! Any ideas what might cause this behaviour?

did he build yours with the abillity to run seq injection?

Yes.. He said it supports sequential.

Edit: Reverant's customer support has been excellent. I just wouldn't want to bother him constantly since i bet he's got loads of things other things to do as well..

Yes, all my Enhanced MS2 provide sequential. Otto, please replace each injector with a 12V auto tester, , and using the test mode, see if you can get all 4 "injectors" to light up properly. When you test each injector, only that injector must light up and none other.

Bought four tiny lights with leads and tried the test mode today.

When in batch injection:

"inj1" powered injectors 1 and 4
"inj2" powered injectors 2 and 3

When in sequential:

"inj1" = injector 1
"inj2" = injector 3
"inj3" = injector 4
"inj4" = injector 2

Everything seemed to work as supposed to.

One thing i noticed is that the rewiring messed up my VE-table tune a bit and made the idle a bit rough and shaky.

idle should be smoother!

Yeah.. What i meant was that i did the rewiring but i still have to run the car in batch injection since it wont start / run in sequential. And when running in batch, it seems to be a bit rougher than it used to.

At first i did fuck up by wiring it so that one of the injectors was getting two signals and one didnt get any (which was obvious as the car started coughing booze out of the exhaust). However, i dont see how this could have caused any damage to the engine that would explain any strange behaviour.

I just wanted to let you guys know that I'm trying to run EV1 550s on batch fire in my 11.5:1 compression engine. Shit is retarded. I might as well have hose-barbs for injectors.

would stock injectors max out on your all motor setup?

IDK why you would run such big injectors for something like your setup.

Because that's all I had laying around and dont' own small injectors. I got 550 EV14s because I got a really good deal, couldn't really afford the IDs, and there is no way in hell I'd ever buy anything from Miata Roadster after he cried about me offending him and demanded my ban.

Alright chaps, i got the car running in sequential! The solution was embarrassingly simple: For some reason i had to change my req-fuel from 6.4 to 17.0! Now it seems to be running smoothly at desired AFR even though my injector pulse widths seem to be roughly twice as long as they were in semi-sequential. Judging from the smell there's no unburnt fuel so the AFR readings seem fine to me. I'm running 2 squirts per cycle alternating, although I'm not sure if it makes any difference in this case..

Shouldn't it be 1 squirt per cycle?

Do these settings look right for:
EV14:
https://www.miataturbo.net/attachmen...1&d=1354394913
EV6:
https://www.miataturbo.net/attachmen...1&d=1354394913

Correct your bank 3 and bank 4 battery voltage correction.

Fixed, thanks. Now I'm off to the doctor for x-rays. phale phale phale.