JaeOne3345

ok im damn sure not taking credit for this mod cuz but i compiled a bunch of info into a easy to read write up about the afc 450cc dsm injector set up for our turbo hondas. much much thanks to liam182. additional thanks to vtc civic and the dropshop from the crx perf board. dropshop was cool enough to donate some space on his site for the write up to go along with his own existing picture tutorial which is ****. check it out.
http://www.thedropshop.tv/vafc.htm]h...op.tv/vafc.htm


[Modified by JaeOne3345, 5:06 AM 3/6/2002]

JaeOne3345

mutherbitch
http://www.thedropshop.tv/vafc.htm

Pissoff

yeah thats right
heheh donate space
all in the name of fast *** hondas


[Modified by Usdm ED9, 5:46 AM 3/6/2002]

VTC_CiViC

Looks good

One question though, why did you set yours up to run so rich?? You set it for -35% from 1000rpm and up.. should be more like -45% to idle properly

JaeOne3345

i dunno y but i guess he left out some **** in the parts needed area

Parts Needed:
-APEXi V/S-AFC Fuel Controller (wired like the manual says..no wiring hacks)
-Stock Honda MAP sensor utilized ( no check valves or missing link sort of devices needed for boost up to 10psi w/o CEL)
-(4) 450 CC Injectors found in 91-99 DSM Talons/Eclipses/Lasers
-Injector Resistor Box from 88-91 style Hondas (needed if your car runs saturated injectors oem)
-Walbro 255 lr/hr high flow intake pump $109 at http://www.autoperformanceengineering.com
-Stock fuel pressure regulator and pressure is just fine in most cases

everything else is coo

DLB1994

can u do this for more then 10psi

DSF

Sure, swap out the stock MAP sensor for a 2/3 bar unit and recalibrate your fuel percentages.


[Modified by DSF, 6:51 AM 3/6/2002]

VTC_CiViC

I did 12psi last night on -35% trim, no problems. This on 440's and stock fuel pressure.

DSF

JaeOne3345

hes running the -35 cuz hes non intercooled on a 235k motor..needs a lil extra fuel at the boost levels hes running especially

14eight

can you use 440cc saturated injectors from RC Engineering??? just wondering, this looks great thanks for whomever discovered this.

JaeOne3345

yeah.. if u got the cash for high flow saturated go for it ..if ur car runs saturated stock..u dont have to run the dsm..its just a cheap alternative..and only the stock saturated cars gotta use the resistor box....for example the 88-91 civics can just use the injectors as they r (electronic wise)

niedejb

I know you did this not too long ago.

Any worries about the MAP sensor mechanically holding up to boost. Not sure the risks or how much they are to replace.

Definately a genious way of doing things.

Someone mentioned a potentiometer in line with the map on a previous thread. Any thoughts on this?

liam821

My MAP sensor has over 220,000 miles on it now...and 30,000 of that have been boosted miles and i have had no problems as yet with it.

So im pretty sure the honda MAP sensor is fine!

liam

liam821

If you swap in a 3bar sensor you will have to reprogram the honda ECU...and the only ECU i know which will do this is a hondata which can understand boost anyways. You cant run a 3bar sensor with a honda ECU and expect the correct fuel tables.

Remember the air/fuel ratio of the engine is LINEAR. If you change one side you need to change the other side too! IE change the MAP scale you need to change the fuel scale to go along with it.

thanks,
liam

DSF

Unless I have been misinformed (happens often ), most standard 3bar MAPs still work on a 5V scale.

But that's what your already doing. When you run boost to the stock MAP sensor, your changing the voltage scale that the ecu "should" be seeing. You ARE reprogramming it to an extent by altering the MAP voltage with the AFC. Well, your actually just recalibrating the fuel scale. So, with a 3bar MAP, you will actually need to run a LESS negative fuel correction. Example: At atmoshpheric, my MAP gives out 2.88V. While I don't have mine hooked up yet, a 3bar MAP should read a lower voltage at the same pressure because of it's greater range of pressure, but same range of voltage. Again, this is assuming the info I have about 3bar MAPs being on a 5V scale is correct

VTC_CiViC

5 Liter Eater

I have decided to start acquiring the parts needed for this route of fuel delivery. Either AFC hack method has got to be better than my 310/FMU setup and everyone appears to be pretty happy with it.

Has anyone run this method with a supercharger? More specifically a JRSC.


[Modified by 5 Liter Eater, 10:42 AM 3/7/2002]

EE_Chris

You would be correct about the GM 3 bar MAP sensor being a +5V reference sensor.

Like DSF said, your trading RESOLUTION for RANGE (or would that be vice-versa...ehh, whatever).

5 Liter Eater

Not only are you giving up resolution for range but I've been thinking and I think it may be a coincodence that taking ~40% out of the 440-450cc injectors delivers the same amount of fuel as the stock injectors while out of boost. If you ran a 3 bar MAP you wouldn't need to take out 40% to avoid tripping a MAP MIL but you would still have to run -40% to trim down the larger injectors to act like stock ones out of boost.

Am I right?


[Modified by 5 Liter Eater, 12:42 PM 3/7/2002]

VTC_CiViC

If the voltage references between the Honda MAP and 3bar MAP are the same yes, otherwise you might need to trim a little more since you'd be cramming everything from vaccum to 3 bar in the space of only 5V instead of vaccum to only 1bar, therefore making vaccum to 1bar a smaller area on the map, and less voltage than what it would be on the Honda MAP.

DSF

Yes and no. You will still physically have to trim down the injectors @40% to get them to imitate stockers. BUT, the 3bar MAP will automatically create it's own partial negative trim because of it's reduced voltage output in vacuum (and in boost for that matter).

5 Liter Eater

How do we KNOW that -40% is what to vut 450's down by to equal 240's? When you're playing with fuel pressure there is an equation: New Injetor PressureOld Injector Pressure)*(Old Injector Size/New Injector Size)^2. Since we can only guess at what happens to the pulsewidth when you reduce the MAP voltage by 40% I wouldn't think there is an equation for this application. Has anyone analyzed the short and long term fuel trim at -40% (can't remember if I saw LTFT #'s in anyone's posts).

Not bashing by any means, I just want to get this down to an exact science. I guess when you go to the dyno you would want to change the percentages at different RPS's based on the A/F plot anyway as long as you don't change them enough to trip a MAP MIL.

5 Liter Eater

I think with a 3 bar MAP sensor you would have to trim less out. Since there is more boost area to work with within the 5V, the atmospheric value would be closer to 0V so you would have to trim less off so as not to trip a MAP MIL.

It's a moot point though because you still need to trim off ~40% to make the 450's emulate 240's.

liam821

Yes correct..the 3bar is a 5 volt sensor too. BUT it steps up at a different scale. So as AIR increases the honda ECU isnt going to add as much fuel as it should.

The more the 3bar MAP reads..the more lean your engine is going to get. Because you are adding another 1bar of air reading into what the honda ecu doesnt know about. (you cant change one scale without changing the other)

Look at it like this...if you are removing 40% with your afc so it idles (lets call that the lowest reading your map sensor is going to read) and as the MAP increases..it increases at a smaller scale....as the farther away from idle you get the leaner your car is going to be.

Like i said...AIR/FUEL is linear. To change one you have to change the other. Thats why with a hondata you have a 3bar check in the software which makes the ecu work correctly with the 3bar sensor.

You cant just swap in a 3bar and expect everything to just work correctly because thats not the case.

With the AFC hack and a 2bar you are moving a set percentage (-40%) so as the MAP moves up through the honda fuel maps its moving at the same scale...thats why it works. You are just shifting the scale so you allow yourself room for boosting.

My friend and i installed a 3bar by mistake (we thought it was a 2bar) and we wondered why the car ran soo lean. We had to run mad fuel pressure but then idle was all rich. Once we swapped in a 2bar that fixed all the problems.

liam