http://www.angelfire.com/ab7/diymaplimiter/boost.html

You'll notice that I've taken the rightmost 5 columns and compacted them down so the stock map takes up ten columns instead of 15. I used linear interpolation. The emptied 5 columns contain the tenth column spark advance data minus 0.75 degrees per pound of boost (as Hondata recommends). I just did the low cam ignition table for a PR3 ECU, but the remaining tables would be adjusted similarly. In order to work correctly, you have to run a voltage divider with the ratio 643/1101 = 0.58 on your MAP sensor input to the ECU.


[Modified by filetofit, 10:53 PM 10/6/2002]

 

Keep it up

 

Tom

 

How does the stock ECU read boost to make use of the last 5 columns?

Also, what if variables changes like temperature, altitude,etc ? Burn a new ROM or something?

[Modified by 4 Stroke, 3:34 PM 10/6/2002]


[Modified by 4 Stroke, 3:45 PM 10/6/2002]

 

awesome man, keep us informed!


Rob

 

 

The voltage divider on the MAP sensor input to the ECU shifts the NA range of MAP values down so that MAP voltages of 1.8 to 3 volts correspond to boost.

Understand that the stock functionality of the ECU is unchanged, temperature and altitude corrections remain unaltered. All this is doing is changing the scale of the MAP voltage versus load characteristic in order to provide fueling and timing retard for boost using the stock map ROM space.

 

 

so this basically does what the hack does, but a little better? I have been reading your post and it all sounds very doable. I am not an eletrical engineer, but so far it makes sense. I was looking at getting a honda data 2b system, this sounds like it would do what that does. keep it up i would love to help out if this gets going!

 

Exactly, the AFC hack scales down the stock MAP sensor input to leave room for boost in the stock fuel maps. This hack would do that plus scale down the stock ignition maps to leave room for boost retard. Do I hear a eureka... anybody?

 

Finally someone who realizes that not everyone needs stand alone user programable engine management. If people can make all these NA chips (Skunk,PYR,MUGEN) Then why cant someone make a Chip that works in conjunction with the missing link that adds fuel and reduces timing or adds accordingly not everyone needs a fuel race setup just something cheap and fast thats good enough for the street. Not the perfect solution but alot better then a NA chip or Stock CHIP

 

Dude you are something else

 

The technology is out there right now on the internet to burn any values you want into a ROM chip for all kinds of Hondas. I've got a guy who's going to put these values into ROM for me so I can test drive the concept. This isn't for someone putting down 600 whp and looking to bring home a trophy and a cash prize. This would be for someone who wants to put down up to maybe 300 hp reliably on the street, using 450cc injectors, without blowing up there engine. They don't want to tune and retune. They just want the damn thing to be fast and not spend a buttload of money. The thing I didn't mention is no missing link or check valves would be needed.


[Modified by filetofit, 1:30 AM 10/7/2002]

 

what do u use to burn the rom chips?

 

Right now, before sinking money into the ROM burner and burner software, I'm just going to have a guy burn one for me for $60, but the software and hardware to burn custom ROMs for Hondas is available for purchase on e-bay and from a guy in Malaysia that I've dealt with before http://www.autoserve.8m.com/

 

What are you going to use to edit the roms? I mean, are you just gonna use some packaged tool and edit the values by hand, or are you going to write some interface?


[Modified by hatchy, 1:47 AM 10/7/2002]

 

That exactly what I was thinking.


This sounds very interesting. Keep us informed on your progress.

 

So that table everything is stock except what is highlighted?
very nice

Someone posted about electrical engineerin, is that what you do?

 

i'll i can say is....DAMN!

 

Oh I see what you mean, I would use a packaged tool and do it by hand at first, Maybe try to come up with an interface later for importing spreadsheet data.
Fortunately the software I've seen for burning custom ROMs for Hondas has the capability of applying scale factors to entire columns of data so doing it by hand wouldn't be too bad.

 

Ok you are obviously smarter than me so maybe you can solve this problem. How do you get rid of the jerkiness cause by the ecu's inability to control 440ccs at ~6% throttle?

 

My own theory is that jerkiness is caused by the fact that you are cutting the MAP voltage by about -40% in order to run the larger injectors. THe ECU interprets such a small voltage at idle to be extremely high vacuum and shuts off the injectors to save fuel. Like when you're driving down a long hill and your foot is completely off the throttle. So the solution would be to add fuel back at idle with the AFC, like maybe a -20% cut instead but only at 1K. THat beefs up the voltage signal that the ECU sees so it won't shutoff the injectors. What you need is a reverse map limiter that puts a lower limit on the voltage that the MAP sensor sends to the ECU. I can make one for you if you want, (I think) but I bet tweaking the AFC will do the trick.

The other possibility is this. If you go to techinjectorsizing on the Hondata website you'll see that they add fuel at low RPM to compensate for the opening time effect of larger injectors. Most people just run a constant across the board cut with the AFC which leaves the opening time effect unaddressed. I suspect that the closed loop algorithm cannot adequately compensate for the opening time effect. The solution again (I think) would be to add a little more fuel back in the lower RPM range.

 

Yup I agree about the interpolation. I won't know if it's a problem until I try. Actually I already made the op amp circuit to do the voltage division. I use it right now in place of an AFC to correct my MAP sensor signal for running larger injectors. The circuit layout is on :

http://www.angelfire.com/ab7/diymaplimiter

 

Correct, the stock map is on top, the compressed stock map plus highlighted boost tables is below.

And my degree is in Physics not EE but close enough.

 

On that site you posted up, it has OBDI chips for turbo cars. How do they function in comparison to your idea?