Type-GS-R-Turbo

I discovered something very interesting awhile back and I've been wanting to share it. I'm gonna feel real dumb if I'm not the first person that thought of this.

If you have the need to run big injectors, lets say 440's like I have. Buy a GM 3 bar map sensor, wire it into your computer, stick your injectors in, and the car will run perfect.
If you need to add or subtract fuel, hook an Apexi AFC in the mix, and you have fully tunable fuel, and instead of your baseline being -40, your baseline is 0.

How does it work? I'll explain.

Stock injectors are somewhere around 200ml. 440 injectors pump a little over twice as much fuel in all the time. Your map sensor signal strength primarily determines your injector duty cycle. Your stock map sensor is calibrated so that 3.0 volts is 0 psi. The GM 3 bar is calibrated so that 1.6 volts is 0 psi. 1.6 volts, is a little under half of 3.0 volts. What this means is that the GM sensor sends out a low ball output to the ECU, and the ecu cuts the injector duty cycle in half, making the car run perfect.
For all you guys who are running the afc hack and want to see your fuel curve so that it isn't way off the scale, on your Apexi, goto ETC. > Sensor type, set Out to 14 and keep your input at 06. Set your -40's to 0's and your car will run just right.

The sensor number 06 is the code for the stock honda map sensor, and the sensor number 14 is the closest you'll get to the GM 3 Bar setting. Say you want to run stock injectors with a GM 3 bar map sensor, set your input to 14, and your out to 06, and the AFC will automatically convert your GM map sensor signal to a Honda Map signal, and then you can tune your fuel curve.
On my car, I'm currently running the GM 3 bar sensor, My Apexi Sensor settings are 14 input, and 14 output. This means GM in, GM out. The GM out compensates for the big injectors and sets my fuel adjustment baseline at zero. Since I'm not running a missing link device I just lean my curve under wide throttle to -7% from 3500-9000. That has worked so far with 15 lbs of boost. I'm running an FMU because I would need rediculously large injectors to run stock rail pressure on 15 lbs. of boost. The setup works great, however I do get the occassional bog between 2 and 3 grand, but I'm working on a solution to that at the moment. If you have any questions, let me know. I have spent great deals of class time researching and a great deal of time almost getting in wrecks trying to figure this apexi out.

Used to say 4.2 volts, I've been corrected to 3.0. That would explain some of hte debate. later on<IMG NAME="icon" SRC="https://honda-tech.com/forums/images/smilies/acura1.gif" BORDER="0">


Modified by Type-GS-R-Turbo at 12:08 AM 6/10/2004

boosted hybrid

This same type of hack is done on Isuzu speed density equipped cars (impulse rs, lotus elan, etc). They are able to run 550cc with the 3bar and the AFC, with subtraction of fuel as a must on the top end of the fuel maps. It just essentially making the resolution smaller on the fuel maps, allowing for larger injectors to be idled and driveable.

keebler65

does this fix the warm hard-start problem?

M.A.R.C.

wow this sounds interesting. i think i need to try this.

turb

good thinking man!

so this with only work with an afc or can you ditch the afc altogether and just use a GM 3bar sensor and 440cc or 450cc injectors?

and you do need any modifications of the stock harness to accomodate the GM map sensor?

lazerus

holy **** batman, boosted hybrid is correct! :-)

cool find though.

turbodGSR

stock honda ecu reads approx. 3.0v @ atomsheric not 4.1or4.2. a stock n/a map will throw a code if u do go over approx. 3.1v. if u use the 3 bar map it acts like a -58% fuel cut so u have a loss of resolution. also the timing curves are way out of wack with the hack and get worse with the 3bar. the more boost u run, the leaner the car will go because both of the maps have a linier output. i have been studying fueling and timing alot lighty but u shouldn't use an fmu with that set-up. wouldn't 550cc or 660cc injectors be better because 440cc are maxed out around 325whp@45psi. 440 are approx 40% larger then stock so i would think u need a larger injector considing EMS guys run 800cc injectors w/ stock ecu when they have had promlems.

Type-GS-R-Turbo

I use the FMU because of what you're saying. If 440's max out at 325 whp@45 PSI, then I need something to raise the fuel pressure. That's where the FMU comes in. You might be right about the voltages and it leaning out, but if you have that problem, you can simply raise the voltage with the afc.

TKERacer619

Well i have one 3 bar gm map sensor sitting on the firewall left over from my mf2.

I think i am going to try this later on in the week after i put a new fuel pump in... I think mine started to give up yesterday.

I will let you guys know.

Hey read your post carefully I don't understand when you at first say to leave the input at 06 and change the output to 14. Then you say you have yours at 14 in 14 out. So why is yours like that but mine should be 06 in 14 out????

TKERacer619

Ok so here is what i find. Please correct me if im wrong but this is how i read the books for wiring purposes.

Gm 3 Bar
Pin A: Ground
Pin B: Sensor Out
Pin C: +5 volts

Honda 1 Bar
Wht/Yell: Sensor Out
Grn/Wht: Ground
Yell/Wht: +5 volts

Again Please correct me if im wrong..

TURBOED-TEG

My question is why are you needing to run a FMU...I thought that with the hack you didn't need a FMU anymore...since you are using one, what disk do you have in it?

Also, wouldn't a MSD-BTM6 resolve any timing issues? I would like to see a list of your total setup...I have some DSM 440cc's and plan on doing the hack, I just want to make sure it is done the best way the first time!!

swrdply400mrelay

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TKERacer619 &raquo;</TD></TR><TR><TD CLASS="quote">

Hey read your post carefully I don't understand when you at first say to leave the input at 06 and change the output to 14. Then you say you have yours at 14 in 14 out. So why is yours like that but mine should be 06 in 14 out????</TD></TR></TABLE>

B18C1CYA

so if you add the gm 3 bar then it lets you run higher boost then the factory map sensor? well i am useing the hack with dsm 450s and i am looking to run more boost so. Whats the deal with the timing being way off ? i read in one of the posts.
any input please would be great.

T3T495GSR

wow, that sounds interesting, and to think just yesterday i was thinking of gettting a 3bar map so i wouldnt get a cel running the hack

turbodGSR

if u do a search on the hack u will find out why it advances timing under low vac./high rpm's. the only way to change that is to reprogram the ecu. the btm only pulls timing under boost conditons to effect ur total timing.

T3T495GSR

so this new discovery is a waste of time?

psileepR

Very intersting... Bump for the lunch crew any other insights???

Finest

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbodGSR &raquo;</TD></TR><TR><TD CLASS="quote">if u do a search on the hack u will find out why it advances timing under low vac./high rpm's. the only way to change that is to reprogram the ecu. the btm only pulls timing under boost conditons to effect ur total timing.</TD></TR></TABLE>

Hmmm, this sounds promising. I know that with the AFC+450's, people are reporting timing issues with high boost. (Don't want to advance too far w/boost) And seeing as the AFC *fools* the ECU into thinking it's still in vacuum, it advances timing in higher rpms.

THIS method basically *resets* the AFC back to ZERO, thereby allowing you to run higher amounts of boost w/o having the ECU advance your timing. Correct?

BTW, what's the boost "limit" w/o throwing a code? 2 Bar?

TKERacer619

Ok so here is what i have found.

I installed the 3 bar map
Put my sensor range at 14 in 14 out (required to idle)
Sensor range at 06 in 14 out (car shuts off)

6psi throws the code

So im not entirely sure but I will continue to try this setup and see if i can get it to throw no codes......

btole

how much does the gm 3-bar map run? $100?

Joseph Davis

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbodGSR &raquo;</TD></TR><TR><TD CLASS="quote">stock honda ecu reads approx. 3.0v @ atomsheric not 4.1or4.2. a stock n/a map will throw a code if u do go over approx. 3.1v. if u use the 3 bar map it acts like a -58% fuel cut so u have a loss of resolution. also the timing curves are way out of wack with the hack and get worse with the 3bar. the more boost u run, the leaner the car will go because both of the maps have a linier output. i have been studying fueling and timing alot lighty but u shouldn't use an fmu with that set-up. wouldn't 550cc or 660cc injectors be better because 440cc are maxed out around 325whp@45psi. 440 are approx 40% larger then stock so i would think u need a larger injector considing EMS guys run 800cc injectors w/ stock ecu when they have had promlems.</TD></TR></TABLE>

This man is correct.

Cincy, huh? You know blundar?

Joseph Davis

Oh, yeah - everybody else: Welcome to last week.

turbodGSR

u can get a 3bar map for around $60. even though the vafc is close to zero it still acts as a voltage cut,the same as cutting the voltage with the afc. at approx. 1050mbar or 0'' the ecu thinks its at 10'' or so.

TKERacer619

Duh...... As im sittin here thinking i might have discovered my problem..... maybe not

Holla If you know somthing about it!!!!!!!

turbodGSR

ya i know blunder, i have been talking with him alot lightly. he is a good guy and a wealth of information. i have been having some electronic problems and he has been helping me out, sorry to get off topic guys.