Jaycar DFA opinions from users

[wiso]

hey guys, did a search, didn't find alot on this topic strangley.

I was in jaycar today and was having a look at the Digital fuel adjusters and hand controllers here and here. they kind took my fancy for their price, I am thinking of getting one.

the guy in store couldn't tell me much about them so i turn to the wider toymods community for your opinions.

Do many people use them? what do you think of them? do they do the same job as branded item like SAFC? are they easy to use/set the fueling points? does it hold its a/f r's once set, or if you remove the power do you have to do it again?

or anything else that could sway me one way or the other.


I would like to hear if any people are using them with sucess on a 1J primarily. as thats what i plan to put it on. I am not really looking to make more power out of this, just remove some of the excess fuel as we all know, toyota used too much

[2JZR31]

I just built the hand controller and DFA. I need to bench test it then I will install it on either my 2JZ or my brothers 1JZ. I have a SAFC on my 2J ATM.

One problem is that it that the DFA is only mappable via load points and no RPM points. It has awesome resolution on those load points though.

The SAFC only has 2 load points which you can set as throttle position points. What the SAFC does have is RPM points which is a bonus, but given the shitty 2 load points it is hard to tune safely.

Now if you have an engine that runs fairly even AFR's across the RPM band the DFA will work better than the SAFC I think. The 1J's and 2J's seem to run quite rich with AFR's staying fairly similar across the RPM band when its on boost. This means you can just subtract map sensor values from any given map sensor voltage and it should give a good fuel curve. And since you can tune each load point it will run better AFR's as it comes onto boost compared to a SAFC.

[wiso]

sounds good,

this was my last dyno sheet you can seen the AFR's were very even. since then though it has better flow now and she runs a little more boost so i am expecting it to have dived a little which is why i am looking at this option, I am going to dyno her next week to check it out though.

[Ben Wilson]

I used a Digital Pulse Adjuster to control my water injector, it worked fine, but took ages to program..

[2JZR31]

Wiso you need a chart with AFR's VS Boost. That way you can work out what you can subtract quite easily. Your chart starts off lean and goes rich. This will be able to be tuned out with the DFA as long as boost was rising the whole way. But for example, if from 120km/h onward you are running the same amount of boost (AFR's from 11.8 - 10.8) you will only be able to tune the that part of the RPM together as it is the same load point. So you can subtract say 10% from the load point corresponding to that boost level and it will make AFR's go from like 12.6 - 11.6 over that same RPM band.

[wiso]

hmmm sounds like the go, cheers man. like i said i am getting her run on the dyno next week, so after the power run if i get boost vs afr i should be able to work out something from there.

I am kinda wondering how hard are they to tune? cause as someone stated the jaycar unit isn't really popular with tuners, so if i was to get it checked and tuned on a dyno would it be easy for the operator to set? or would it be something i would be better to study the graphs and do it myself? with them do you tune as you drive, or do you tune first then drive?

[2JZR31]

I reckon it will take some time to tune if you are flying in the dark. Your best bet would be to do a run with AFR's VS boost, then you can calculate what to subtract. You should also know what boost level corresponds to what MAP sensor voltage level, and you should know what load points on the DFA correspond to what MAP sensor voltage level (and therefore boost level). You also need to know exactly how much voltage the DFA will add and subtract with each point of adjustment. I doubt most tuners will have a handle on this which is why they hate them. If you figure it all out first it will make it a lot easier.

Its a fair bit to nut out, but once you have it sussed you will be able to make accurate adjustments after one dyno run with AFR vs Boost. Take note of how much you adjusted and what effects it had on AFR's, then re-adjust and do another run. I reckon you could do it 3 dyno runs if you understand what effects the DFA will have on map sensor values.

[wiso]

cheers dude you have been a huge help

[jonra23]

Have used one with an exhaust o2 sensor tuning an rb30 with RB25v head and computer and the DFA gives pretty good results, pretty intuitive to use by adding or subtracting where required.

regards
jon