Digital fuel adjustment - Sugsetions!
 

My car:

86 NA (fully tuened, EU version - no O2, cat, AFM reads 0-12V)

problem is since i can,t install S-AFC so i am thinking going on this mod

http://www.autospeed.com/cms/A_2418/article.html

any sugsetions ???

looks old school. unless you are used to working with beakers and bunson burners, i'd stay away! LOL

Why not just get a stand alone ECU?

thx

i dont think that there is stand alone ECU for this model (smaller harnes??)

That unit functions almost the same an an S-AFC.
The hook up is identical.
In generic terms, they are both piggyback units.

Another option is a rising rate fuel pressure regulator.

rising rate fuel pressure regulator is also an option but did you see price of that it is round 100$$

Can you swap in a US spec ECU? Would you have to swap harness or coils and such?

SAFC 1 is about 100$ going price in the fs sections.

Good idea. That's the only fuel controller I've ever heard of that can work with 12V AFM systems and Autospeed have documented it's successful use in a wide range of cars.

The only downside on a rotary is that because its adjustments are load-based (rather than rpm-based like an S-AFC) it won't work properly with different-sized primary and secondary injectors, i.e. if you've upgraded the secondaries from stock. But this isn't a problem with NA's since injector upgrades are unnecessary unless you get into serious porting.

Actually it's only a couple of years old. Don't confuse simplicity with lack of ability. Strip away the fancy glowing screen and the eleventy billion ways of displaying six numbers and an S-AFC is no better. In fact the S-AFC has far fewer tuning points.

Because the cost and difficulty of install is about the same right...?

Um, it's an NA. Not only does is not need any more fuel, it does not boost... ;)

They don't work with 12V AFM's.

It's just an S-AFC with more adjustment points...
More doesn't necessarily mean better...

In fact, I don't see the word "interpolation" anywhere in the article, which means it requires all those load points so you don't run into trouble.


-Ted

It's hard to see how 80-90 points of adjustment isn't better that the S-AFC2's 12 points...

Did you actually read it?

"It interpolates between the steps (ie smooths the curve of the adjustments)...

...on the subject of driveability, it is brilliant – we spent over 24 months and thousands of kilometres trialling the DFA in different cars... and if the modified air/fuel ratios are set correctly, the drivability remains absolutely factory."

I don't see it carrying the APEXi brand name do you? To reword what you wanted to say, "Its just another piggy back fuel computer".

More adjustable points means a smoother more accurate AFR across the board.

thx guys you helped me a lot with this discusion so i think i will go for it since there is no other way to tune my fuel curve wich is very rich in EU cars (fully tuned gets 13MPG).

i would apriciate some sugsetions on how to tune this (with wideband and dyno ????)

Holy crap!
You got nothing better else to do so you interpret things with your own English?
Stop wasting my time.

Better yet, you go on the ignore list already, since you never offer anything useful.


-Ted

Guess not...
Too much of it went "blah blah blah", my brain just shut down after a while.
Though I was conscious enough to just read the important parts, but I missed that part.

Don't really care about products like this.
I haven't messed around with an S-AFC in a long time.
It's all full EMS' now...


-Ted

This brings up a question that I have concerning piggybacks: What about closed loop?

Say you put 720 primary and secondary into your TII and use a fuel controller to adjust. Does the N/A ecu have the ability to control the duty cycle to get your AFR to 14.7? Or is this why most people use 550 primaries in the TII, to preserve closed loop?


And what about a N/A turbo? I understand the N/A vert ecu can run a turbo N/A conversion. Does this mean that the Vert ecu can attain Stoic with 550 primaries?

The last time I had a SAFC in a car, the closed loop function of the ECU would over ride the SAFC. I'm talking closed loop driving, not WOT. Not idling. Just Closed loop.

Right. My question is in a N/A, if the primaries are upgraded to 550, is the ECU in closed loop able to pull back the fuel enough to attain 14.7? Or is the 550 too much injector? Will it run rich in closed loop?

thx

Don't you think that's a tad hypocritical since you couldn't be bothered reading the article, posted incorrect criticism as a result, tell us you don't care about piggybacks, and have no useful input? Why post? Sounds like you're wasting your time.

You mean you made your mind up at the start and then just tuned out...

In closed loop the AFM input is ignored, so any AFM interceptor will have no effect. This isn't really a concern though, because the conditions that closed loop is used in suit stoichiometric mixtures (which is the whole point of closed loop), rather than what you may have tuned with a fuel controller.

Good question, and probably best answered by experimentation. It might work, or you might find there are set limits to how much correction the ECU will apply to preset values when trying to achieve a stoichiometric mixture. Personally though I'd never try to run four 720cc/min injectors with an NA ECU and a fuel controller. You'd need to use a whopping -36% correction just to get to the stock mixtures, and that's going to result in a lot of unwanted ignition advance (or more correctly a lot less retard). Not recommended for turbos...

Personally I wouldn't want to go below -20% correction, which means up to 690cc/min secondaries and stock primaries on the NA ECU or up to 825cc/min secondaries and stock primaries on the Turbo ECU. If you need more fuel than that you should get a standalone or just put up with richer-than-ideal mixtures.