poorman's hondata afc hack

dont know if anyone has posted this or not. its from liam821 on honda-tech. this is his original post so you get the gist of it. the link has most questions and comments on it from the post on honda-tech. pretty damn cool.


Im sure you all know about the honda-tech afc hack....poor mans hondata. Where you control boost using an afc with a MAP sensor hooked up to the TPS on the apex...i found a better one.
When i rebuilt my last engine i didnt want to use the secondary injectors (f-max erl mf2 fuel system although i had 550cc secondary injectors not 440cc) anymore and wanted something better. I read about the afc hack and thought i would give it a shot. I have a dsm so finding dsm injectors were easy.

My first impressions once i had it all working is...well it worked! I got the boost up to 9psi and it seemed to work pretty good, at least at WOT. EGT and a/f gauge both showed good numberes, and i was also monitoring the o2 voltage by using the "blue wire mod" on the afc which was also good.

The problems started happening while at 1/2 throttle. I drove my honda to oregon from san diego last week and going up and down through the mountains really sucked. I kept having to change the damn cross over point from vacuum into boost on the afc to match the current altitude so the car wouldnt run lean. But even with the right cross over point the car would start going into boost and the honda computer would change the air/fuel from rich (cuz of the afc) so a leaner value. (thats what close loop mode is all about right?) I could watch the EGT increase as this happened. There was also a stumble as the honda computer fixed this. It was pissing me off to no end.

So for a few hundred miles i was playing with the afc trying to make it better...and i just couldnt get it right. So then the thought came.

The afc hack you use a MAP limiter, and then step up from a negative value for fuel with the afc (i was stepping up to around +5%) once the car starts to boost.

So i was thinking, isnt a limited MAP (with a missing link check valve whatever) and the afc stepped all the way to +5% the same as an unlimited map with the same boost? (that is if i got the damn thing tuned right)

So i pulled into a gas station and modded the fuel system. I removed the missing link so i had an unlimited map. I set my AFC at -40% from 1000rpms to 8000rpms so it would keep it no matter what boost level i was running.

I started the car....and it works. It works really well. Its night and day difference. Its AMAZING. In and out of boost you cant tell the difference from a driving stand point. Transition into boost...well there is no transition..its not there because its that smooth. Its as smooth as my eclipse. 1/2 throttle into boost is the same way. 1st gear burnouts feathering the gas so you dont slam the rev limiter...smooth as silk as if you didnt have a turbo. Its a poor mans hondata only i think its just as good.

EGT, a/f, and o2 voltage are all good also.

I have a friend with a b16a/turbo in a 95 civic coupe running 7-9psi. He was running the afc hack like i was. He drove my car...almost drove it off the road because of the torque steer (hah gotta love the d-series axles) but was really impressed by how smooth it was. We rewired his AFC back to stock removed his check valve set his afc at -40% across the board and took it for a spin. The first words out of his mouth were "wow..what a difference that made..its smooth." His over rich in boost, ugly transitions, and all the other bad side effects were gone. Hes using a p28 chipped ecu with a dohc mugen program.

So this is my currect setup:

d16y7 block with z6 head (hey it was cheap) z6 head gasket
p28 ecu (stock unchipped)
99 Turbo DSM 450CC injectors
89 CRX Si resistor box
Apex AFC fuel computer
Walbro 255 lr/hr high flow intake pump
Stock honda MAP sensor (connected to the t/b in stock location not limited)
Stock honda FPR (off the the fuel rail)
Stock fuel pressure, ~40psi at WOT, increases as car boosts. (1:1)
boost set at 10psi regulated with an apex avcd boost controller
garret t3/t04e .48a/r 54 trim

apex fuel settings are, -40% from 1000-4000rpms, -35% from 5000-8000rpms (to be safe i increased the 5000+ rpms by 5%). The settings are the same on high and low throttle settings.

I dont get a CEL with 10psi of boost, but i do with 11psi. Im sure if i changed my high rpm fuel from -35 to -40 i could squeeze a little more boost outa the system but i dont wanna push my stock mutt engine any father then it already is. But i have been running around with 10psi with this system for a while now without any problems what-so-ever. And i have been really enjoying good gas milage and just awesome throttle responce.

I highly highly highly recommend this setup for anybody that wants a cheap hondata like driveablity without spending the money. Almost everybody has a afc and DSM 450CC injectors are really cheap. Not to mention you dont have to hack anything..just set fuel at -40% and go with it and have the afc wired like its supposted to be.

Comments are welcome.

liam
_______

93 Honda Civic Si Turbo
95 Mistubishi Eclipse GSX
http://www.turbocivic.com/liam/

http://honda-tech.com/zerothread?id=137901

sweet mod man, i was considering this for when i swap and go turbo...i have the site that shows how its done bookmarked if anyone wants it

nice hook up man... thanx for the details.. too bad i didn't read this a week ago i just watched my bud blow his engine settin it up wrong..

it deffinatly works thats for sure. i have been preching this to alot of people but they seem weary of doing. they think the dsm 440's will flood the engine somehow even though the damn fuel is cut 40%. anyways its a damn good problem solver if you can afford the hondata. what better to do fuel correction then the stock honda ecu ya know.