Re:tuning with an FMU
 

its fairly obvious looking at your car youve got some money invested in it.Why sel the most crucial aspects of its performance and driveabilkity short by Running it in a hacked up ass manner. You could oconvert to a p28 or a p30 ecu run one of the manny boost romds avaiable. run a hondata and get it tunned much mroe accurately then with an FMU a BTM and injectors that are to big.

As for the injector resistor. Are you fimilair with ohms law ? bascially the lower the impednce the higher the current flow

for example

12v x 2 ohms = 6 amps thats 6 amps everytime the injector gets turned on it happens alot ;D

now

12v x 10ohms = 1.2 amps.

It has to do with the amount of drive durrent needed to turn the injector on. Most of the obd1 pcms are unable to run high current. so you have to run a resistor like so

2ohm injector + 10 ohm resistor is 12 ohms.

12v x 12ohms = 1.44 amps.

there are beter ways to run low impednec p/h injectors. I sell hardware for this but its not cheap and with a set of 450cc injectors id highy doubt you would ever need the super stable controll and short PW time to validate its cost on a 10-12 psi car with such a small inector.

but lets explian the advanatges of p/h injectors Vs saturaed or high impedence injectors

there are 2 modes of operation

a saturated injector open on what can best be reffered to a bell curve. current slowly ramps up and open the injector. the minimum amount of time it takes to open and close the injector given the physical limitation of the design are 2.5 msec or so. They also require less current becuase they are high impednce. typically 1.4-1.amps

A peak hold injector is a slightly different animal.

it will rip the injector open with 4 amsp of current ( are box does this in .9 msec) and then it lower the amoutn of current from 6 amsp to .4-.5 amps. whats really important about this is is the amount of time

the minimum PW with a p/h injector is roughly 1.4 msec
the minumum pw with a satruaretd inejctor si 2.5

well when you trying to control a lrage volume injector at low air demands like idle with out the short PW time the peak hold injector can deliver it make the idle typically over rich.

Just a bit of info.

Re:tuning with an FMU
 

Sean, as accurate as what you say may be, its over the heads and overkill for many of the questions and people here.

Accord dude:
the "AFC Hack" has become more than just using an AFC. What happens with the motor when you use the AFC hack is that the MAP signal gets scaled to a lower figure. You do not get a check engine light running 8psi (for instance) because the ECU sees 8psi scaled (usually about -40%) with an AFC, which is no longer a boost signal. It no longer sees boost, so it just happily fires an injector, which happens to be a nice big 450cc injector. The car gets approximately 450/240 times as much fuel, and runs quite happily in boost.

Point being: you can scale the MAP signal with about $10 of parts from radio shack and have the car run just fine. There is a turbo 97 H22A prelude running 10psi with a t3/04e and 550cc injectors running well on nothing more than a MAPhack of sorts.

Re:tuning with an FMU
 

blundar: wow, that answered so many of my questions. A DIY of that Radio Shack project you described would be fantastic. Anyone?

Re:tuning with an FMU
 

thanks a lot sean88accord...a little over my head. but thank you for the explaination. Thank you as well blunder..for putting it in more lamens terms.

jsut let me get it straigt...are you saying i can use the AFC hack/450s without a resitor box using radio shack componants? or are you saying i frankly dont need an AFC at all?

Re:tuning with an FMU
 

yes/no

You do not need an AFC box. you can use a voltage divider circuit (hint: read some of the threads above carolina hondas ... Joseph's post) which can be made from about $10 in radio shack parts.

You do not NEED a "resistor box" with 450cc injectors, but you NEED something. You can substitute 4 resistors from radio shack, but I forget the resistance you need. If you do not use something, you will cook your ECU. Someone else can probably answer this for you. I want to say 1 watt 10 ohm but I'm not sure.

Using resistors is ghetto, mind you, but honda did it from the factory on many of their cars, and it works. If you are curious why it is ghetto, you can ask Sean - he explained it very well to me.

Re:tuning with an FMU
 

Here's the schematics of the MapHack that Joseph Davis created. XDEep used this for a while, said it worked great!

Just sort of makes it hard to tell where to tune your maps.. (because of the scaling)

http://www.carolinahondas.com/forums...ht=trailerpark

Re:tuning with an FMU
 

actually you dont need a resistor box at all to run the 450's. Our accords already have a resistor box built in and run low inpedence injectors. Trust me. Your car is either a 93 or 92. On my 93 I ran the afc hack with 450s and had no problems. If you want you can look at the box yourself, its the silver box on the right side of your engine bay (its about 1 by 2 inches) below the strut tower.

Re:tuning with an FMU
 

Well.. just lowering voltage won't help.
I tried this myself with 345cc injectors.
What was wrong?
Well.. I did study it somewhat... and here are the issues:
When decelarating MAp signal wouldnt be decreased enough, so even touching gas pedal would cause backfire. Ad decelaration MAP reads arround 0.3-0.4V.
THis is a problem, cause at idle it reads arround 0.9V - if you lower it too much, you'll get erratic and jerky idle. Lowest you can go with 345cc is near 0.65V, not lower.
Next... at very light gas (like 5-10% throttle), and arround 3-4krpm - when you just try to keep the speed in 1st/2nd gear you'll notice sputtering.
This is due to pretty high vacuum at that throttle position and revs which causes MAP signal to go down quite a lot.
Decreasing it more (due just to reducing voltage) makes ECU think something crazy, thus cutting of fuel (too much vacum) and making it sputter.
At 1/3 and more throttle it worked nicely tho... but that sputtering at very low throttle and backfiring makes that unusable (well, at least for me).
This is why you need more complex electronics to controll it.