J337_UNIT

I saw a few old topics related to this but im not 100 percent convinced yet because i need concrete answers to this question..

Im going to be running the AFC hack. I have read that timing will advance under boost. SO to correct this i should use a MSD BTM..now my question is..Is it possible that the stock MAP will see that timming is trying to be pulled, and in return the MAP will override it and continue to advance.. im not familiar with this so someone please give me a good answer.. TIA

Nick7

MAP sensor doesn't messure timing.
It reads pressure in intake manifold.
Due to AFC hack, ECU reads lower MAP input than really is (so that injecotrs get lower duty cycle due to larger size).
However, when ECU reads lower MAP signal (less air as far as it knows) it also advances timing aswell as lowers duty cycle of injectors.

On the other hand you have BTM, which goes AFTER ECU, and retards timing under boost.
So, first ECU will advance ignition due to lowering MAP signal (ECU doesn't see BTM, and doesnt know what happens afterwards), and than BTM will retard timing (and ECU will *not* try tocompensate that retard - otherwise there wouldn't be a point in doing that).

Hope you got the idea now

JDogg

the thing is.. hte btm will retard the timing when you dont really need it retarded. the vafc hack makes the partal boost timing way to advanced. ie. from 0-8psi, at full boost, 10.9 psi the timing isnt really that bad and you could get away with just a few deg of retard. under part boost you need ALOT more retard than the simple BTM can give you. ( about 15-20 degrees )

imho save your money and buy a chip burner and chip yourself an ecu.

GDM Z28

how can the btm retard timing when it doesnt need to be retarded if it reads boost then retards timing. when you start to boost it will start to retard. so its not like it retards it at daily driving when your not in boost. please explain what you ment when you said it retards timing when you dont need it too.

USDM 4G VTEC

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civicflnum1 &raquo;</TD></TR><TR><TD CLASS="quote">how can the btm retard timing when it doesnt need to be retarded if it reads boost then retards timing. when you start to boost it will start to retard. so its not like it retards it at daily driving when your not in boost. please explain what you ment when you said it retards timing when you dont need it too.</TD></TR></TABLE>

exactly
i am also doing the MSD6 BTM and VAFC hack

JDogg

obviously you dont understand how the vafc hack effects the timin map of the stock ecu. at the point where you need the most retard.. low boost 0-8 or so psi.. the btm isnt gona pull enough timing.. you would have to set it at the max retard per lb to do anything usefull in this area. however at full boost 10-11psi, you dont need as much retard, because the area of the ign map the ecu is reading from has alot lower timing there anyway..

Nick7

Yeah.. JDogg has a good point there. Worst part is when just going into boost, as at that point advancing is most noticable.

At that point (0-1psi).. does anyone know how much is it advanced compared to stock timing?
(assuming you use 440cc injectors.... so you have like -40% on AFC)?

JDogg

ill go dig up some stock bin files i have and get some exact numbers...

USDM 4G VTEC

i have also gathered from my local shop and tuner
he is a dynojet registered tuner

he sys that a thing tha tmost people dont know is that Honda ECU's full time advance around 4100 rpms

with the MSD u can actually retard some of that timming under boost even after te ecu thinks is fully advance also

JDogg

ok... after doing some comparisons i came up with these numbers....

normally the honda ecu has around 27 degress of advance at full load ( 0 boost/0vacuum), it ramps up pretty quickly, and reaches full advance around 4500 rpms. full advance under vacuum (about -10psi ) there is around 40 degrees of advance....

now using the vafc hack you would scale this ign map to allow for the 11psi the stock map sensor can do..... this is what happens...

at 0 vacuum/0 boost you end up with approximatly 38degrees of timing. at full boost (11psi) you have the 27 degrees that you used to have. at 5 psi you have close to 35 degrees of advance...... as you can see, even with the btm set to full retard ( 3deg per lb i believe) you end up with a retarded ign curve

at 1 psi you have 35 deg of timing, at 5 psi you have 20 degrees of timing, the max retard the btm will do is 20 degrees... so at full boost you end up with 7 degrees of timing... which sucks and is not enough.

if you dial in the btm to where it would be safe... about 18-19 degrees under full boost, you would need about 1deg of retard per lb.. that would mean at 5psi you still have over 30 degrees of timing.......

legendboy

I had the same setup when i first went turbo a couple years ago. I would definatly chip your ecu and use uberdata. Sell your afc and use the money for dyno time. your ringlands will thank you

J337_UNIT

so would it be better to run a MSD Digital 6 plus because you could just pull timing accordingly with rpm?

JDogg

im not sure the digital 6 would be of any use either...it only retards per rpm. what you need is something with a fully tuneable 3d timing map.

if you are set on a timing control piggy back the msd digital 7 with boost retard would work. it has a customizable timing retard curve. you can pull more timing at lower boost and less timing at higher boost.

TurboJesse

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J337_UNIT &raquo;</TD></TR><TR><TD CLASS="quote">so would it be better to run a MSD Digital 6 plus because you could just pull timing accordingly with rpm?</TD></TR></TABLE>

why go through all that headaches when hondata is &lt;$400? , or if you know what your doing uberdata is free?

J337_UNIT

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mpir3 &raquo;</TD></TR><TR><TD CLASS="quote">

why go through all that headaches when hondata is &lt;$400? , or if you know what your doing uberdata is free?
</TD></TR></TABLE>

hondata set up is no where near less then 400$... for my car everything would run me over 1500. and im not going to be boosting more then 8psi really, so the afc hack seems very doable as long as i can figure a way to make the best of the timing issue..

CRX T-Si

So the bottom line is th set the BTM at 1lb per boost. right??

What do you set the starting point at??? I have mine set at 2lbs. so after the BTM sees 2lbs then it would start to retard timing.

Oh yeah I was boosting 6lbs but will increase it to 10lbs.

99lspwr

CRX T SI.......

BoostedITR41

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by J337_UNIT &raquo;</TD></TR><TR><TD CLASS="quote">

hondata set up is no where near less then 400$... for my car everything would run me over 1500. and im not going to be boosting more then 8psi really, so the afc hack seems very doable as long as i can figure a way to make the best of the timing issue..
</TD></TR></TABLE>

ok look at it this way:

afc-200 used
MSD BTM- 150 used
that is already 350 bucks and all you are doin in using bandaids. I got my hondata 4B used for 475 with the P28 and 3 bar map. for 8psi the 2B is perfectly fine and will work 100 times better than the hack. I honestly recommend the FMU set up I am using right now over the hack. I have run it I know what it does to your set up. also you will NEVER get the fuel curve leaned enough. with 50% of fuel pulled and 43psi base presure and 13 degrees base timing I still couldn't get out of the low 10:1 high 9:1 AF ratio. my dyno numbers were very much lower than they could have been with the FMU set up.

TurboJesse

Hes gotta convert to obd1, but still it will be no where near 1500, more like 600-700

BoostedSi

could just get the aem also. You wouldnt need to convert anything. You can probably get one for 700-900used. I remember i sold mine for $850.

twkdCD595

this thread is making me want to sell my afc for a p28 and supplies.

überdata or crome...

4sdB20

what about an APEXi ITC?

J337_UNIT

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4sdB20 &raquo;</TD></TR><TR><TD CLASS="quote">what about an APEXi ITC?</TD></TR></TABLE>

what is this?

BoostedITR41

Ignition timing controller- same as BTM really and just as much money. I would say no more than 600 bucks for a hondata set up in your car ready to go if you shop around on here

TravSi

One thing is maybe he wants all the options of hondata that people dont bother buying cause they are comfortable with some stranger tuning there car....I myself would have every option that hondata offers to tune yourself, cause thats what I am comfortable with and so are most people....I dont want some tuner to blow up my car, then it turns into a bitch fight between a dudes blown car and a tuner....so i can see that.......Now i run afc hack I pull 1 degree per psi of boost and I have no problems....I seriously dont know why so many people have hack problems, I have had none..its smooth it works great, its easy to do and I have no issues....I just dont get it......but hey im just a stupid college kid wtf do i kno!