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Jaycar Boost and Fuel Control


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Simplistic at best, there has NEVER been a problem running the engine (of an auto) with a Power FC, been doing it for years.  There has NEVER been a problem for the Power FC to talk to the Auto ECU, been doing it for years.

The REAL problem is the Power FC has no input from the gearbox and zero shift logic programming, so it doesn't cut/interrupt  the ignition when the auto is changing gears.  As a result you get crappy changes, harsh and uncomfortable at low loads and slip at high loads.  As well as being rough, it also wears the gearbox excessively.  The more power the engine has, the worse the harshness and wear get.

Maybe try emailing Zoom and asking them about the REAL problem, I have tried and get no response.  Too hard basket maybe.

:(

SK,

In the S2 Stag with the trip tronic 'box would the above problems still persist if you were manually changing gears via the auto shift (or steering wheel mounted buttons)?

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SK,

In the S2 Stag with the trip tronic 'box would the above problems still persist if you were manually changing gears via the auto shift (or steering wheel mounted buttons)?

Much the same as the Ferrari F430 and the M3, if you lifted the throttle on the upchange it will be smoother. Consequently less damaging on the box. Basically this is doing exactly what the standard ECU does, exept with ignition instead of fuel:cheers:

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Yep, I have to have the Controller plugged in before I turn the ignition on.  Which is a bugger actually because I have the DFA as well and I like to swap over to check/fine tune stuff.  An example, coming down the freeway from Newcastle there are plenty of long uphill climbs to tune the load sensitive settings.  (You can't do that very well on a flat road, as you get up to warp speed so easily.)  I was sitting in the passengers side and I wanted to swap to the DFA to tune out a flattish spot.  But we would have had to stop and turn the engine off, not a good idea on the freeway.

My Controller works perfectly, since I turned up the contrast I have not had one problem.   Your issue sounds like a dry solder joint, most likely on the connector pins (either the Controller or the DFA inself).  I would have a close look around there for any suspect joints.

:D

I am also having this problem with the screen but at the same time the boost drops off completely (at high input loads)

Any ideas??

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I am also having this problem with the screen but at the same time the boost drops off completely (at high input loads)    

Any ideas??

Sorry, I really need more detailed explanation before I can offer any suggestions.:D

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Will most tuners know how to use the DFA effectively. I have read in other threads if the tuner doesn't know what they are doing they can actually make things worse with a SAFC..I guess this is similar

I was going to go to someone called the hitman...apparently he is pretty good wih Powerfcs and safc...

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Will most tuners know how to use the DFA effectively.  I have read in other threads if the tuner doesn't know what they are doing they can actually make things worse with a SAFC..I guess this is similar

I was going to go to someone called the hitman...apparently he is pretty good wih Powerfcs and safc...

The DFA is pretty damn simple, side buttons move to different load points and the top and bottom buttons add or subract voltage to the AFM input on the ECU. The bottom button = lower voltage = less fuel = leaner.

My suggestion would be to spend 5 minutes with the tuner showing him what the buttons do and what the screen shows. Our dyno guy picked it up in a few seconds of my explanation, so it ain't hard.:cheers

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Nice one. Have a couple of further qns if not too much to ask

1. With the SAFC I have seen how it dispalys e.g. -5.0% I guess this is how much fuel is being taken out or is this the amount at which it changes the AFM signal?

So seeing I am not too bad with a soldering iron this should be as good as a SAFC it seems.

2. For an R33 with 10psi boost R34 intercooler and 3" exhaust will I loose much low end power using the DFA as compared to a power FC. These are the extent of my mods. I am wondering the benefits of spending an extra $1k on powerfc and more to tune...

I know the PFC can vary ignition also and is much less compromising. But if the DFA will give a 90% result I'm tempted to go with it...

Thanks

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Hi, I just built the Digital Fuel Adjuster

And with my extremely limited knowlege ( I know what a capacitor, resistor and a diode is)

I have about a year of soldering experience on very basic stuff.

It took me about 4 to 5 hours to build. The instructions are very good the only problem i had was getting the resistors color coded to their values. my eyes are not that great!

I have not calibrated it yet and would like to know if anybody else is in sydney that has built one that would be willing to help me calibrate it and fit it in the car + show me how to tune it correctly.

Also who would you recommend to take the car to to get it dyno'd. The last place i took it to gave very questionable afr's and a very sus power figure.

Also has anyone taken a photo of the completed DFA yet? i didnt buy the electronice for car book.

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Cheers GTRgeoff

I should have done that it would have been a lot quicker but my multimeter had a flat battery :)

Do you need to plug in the hand controller to get the unit to power up?

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Do you need to plug in the hand controller to get the unit to power up?

Nope, it runs quite fine on its own. I only have the Controller plugged in when tuning, the rest of the itme the IEBC and the DFA sit quite nicely in the glovebox:cheers:

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2. For an R33 with 10psi boost R34 intercooler and 3" exhaust will I loose much low end power using the DFA as compared to a power FC.  These are the extent of my mods.  I am wondering the benefits of spending an extra $1k on powerfc and more to tune...

I know the PFC can vary ignition also and is much less compromising.  But if the DFA will give a 90% result I'm tempted to go with it...

Thanks

The best I can do to answer your question is to relate it to what I am doing. I am fitting a GCG ball bearing hi flow, 3.25" exhaust, hi flow cat (that's an interesting story), split dump/engine pipe combo. It already has the IEBC, DFA, adj exhaust camshaft pulley and R34GTT intercooler. The target is 200 4wkw using safe settings and boost. Basically that same set up made 240 rwkw on an R34GTT except it had a Power FC and a GTR intercooler. Let's look at some numbers;

200 4wkw = ~210 rwkw

The GTR intercooler was worth ~10 rwkw = 220 rwkw

So by not using the Power FC I reckon I have dropped 20 rwkw.

Hope that answered your question:cheers:

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Thaks Gary,

But with my mods that don't include the highflow turbo I would think it would be closer...will I loose much low end compared to a powerfc? because some people say that the peak won't be much different but you will loose low end

I find hard to believe unless you can not lean it out enough due to it getting too advanced...

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Thaks Gary,

But with my mods that don't include the highflow turbo I would think it would be closer...will I loose much low end compared to a powerfc? because some people say that the peak won't be much different but you will loose low end

I find hard to believe unless you can not lean it out enough due to it getting too advanced...

You won't loose any low end, the area that is most affected is the boost build rpm range. That range from ~3,000 rpm to ~5,000 rpm where the A/F ratio versus ignition timing compromise can be an issue. The short answer is I don't really know, every car is different. Some it doesn't seem to affect much, others it's a real pain in the ass. The only observation I can make is that cars with split dumps, hi flow cats and 3.25" (or bigger) exhaust seem to be the best in the compromise stakes.

:D

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Thanks for the explanation.

How much does it affect timing if for example you alter the AFM signal enough to go from 10:1 AFR to say 12:1 between 3000-5000rpm. Would the timing be changed by more than 3 degrees? I know the computer alters the timing a lot compared to the base 15deg BTDC...

Jut trying to get a rough idea on the effect of the dfa.

thanks

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