dbman96

OK... the moment you all haven't been waiting for.

Today I swapped the wiring all around as we all discussed in my earlier thread "VAFC idea - call me crazy" such that the VAFC is recieving a non-limited MAP signal into the throttle position input, and a J&S-limited MAP signal into the MAP input, the result being that the VAFC now makes its fuel adjustments based on boost level rather than throttle position . Obviously I have not had a great deal of time to tune it, but I did remove my Cartech so I'm running stock fuel pressure (on my 450cc injectors) and the VAFC is making all fuel adjustments under boost. It smoothly goes from -40% fuel trim at idle to around -5% at full boost. Right now it seems to be a little bit lean under boost but she pulls very strong. Vacuum-boost transition is GLASS smooth, unlike before, even at part-throttle when the ECU is not wanting to go into open-loop mode. So far this seems to have great potential; I'll keep everyone posted as I get her tuned better.

I'll note that G also performed this mod and told me that it worked fine on his car but that he needed to do some further tuning as well.

So far, this seems like a step in the right direction, and a huge improvement over my previous setup especially given that I've only spent 5 minutes tuning it... I will make the disclaimer that this is only useful to you if you have some form of ELECTRONIC map limiter (J&S ultra V.2 is the only commercially available one I know of) and are running larger-than-stock injectors (although it may be useful for fine tuning on a FMU-based setup as well!). I'll try to post my wiring schematic if I can get hooked up to my web server.





[Modified by dbman96, 12:57 AM 10/8/2001]

dustin

Very cool

94turboteg2

electronics, got love it

dbman96

Well, I messed with the tuning some more on the way to work today, and I am definitely leaving it this way; the car seems noticeably more powerful and is completely free of tip-in and partial throttle detonation (is that the same thing?) and overall feels smoother and more responsive. This is cool, I really feel like I have much more control over what's going on in my fuel system with this setup.

b18bturbo

you have the diagram for the electronics. I would like to just take a sneek peek at it . i got webserver if you need hosting of hte pics.

dbman96

I'll email the pic to you, you can post it; I'm having too much trouble with my host.

b18bturbo

recall

lol u are officially the ghetto rigged master. ill hand it to you that if it works its a good idea. im curious if you tune it still with rpm settings and narrow vs wide band "throttle" aka boost. also how do you know what u are tuning since the visuals wont match up properly. hit or miss i guess you do know for the price of the J&S and vafc you could have hondata like the non ghetto drivers out here


[Modified by recall, 12:55 PM 10/8/2001]

dbman96

Hehe... but I'm representing all the poor tools like me who already have the J&S and VAFC and want to make the most of it before we bite the bullet and go standalone.

FIxALPHA

Thanks for the great idea. Now I have to find a J&S.....anyone got one J&S V.2

Im def. gonna try it.....Im one poor boy, still saving for a stand alone.

Full-Race Geoff

Im glad it works!!

Im thinking it may be a bit easier you used my two map sensor idea? We may try this out on my roomates car...

cool deal!!





[Modified by z10 geoff, 7:46 AM 10/9/2001]

HX_Guy

Which roomate Geoff? Shane's car?

dbman96

Hell yeah, buying an extra map sensor would definitely be more efficient than buying a $500 J&S !!

JM Performance

sounds good. apex should make something from the factory like this. its a shame though....you'd know they'd charge a fortune for it


but get that thing dyno tuned and hopefully it'll fly. good luck!

Safir

"Get that thing dyno tuned"

gawd.. i can imagine the dyno-guy's confusion now "throttle position = boost? what? it doesnt create boost just because you mash the pedal..."

Full-Race Geoff

you have two other options

1) run a second map sensor, run that voltage to the AFC

2) find a greddy black box. I use one on my car and got it for 20$.


however you will still need to retard ignition timing under boost so a j&s v2 wouldnt be a bad idea... then again an msd btm would work out too

either way, it can be done lowbuck style and you can get rid of that pos fmu.


[Modified by z10 geoff, 12:45 AM 10/9/2001]

dbman96

Hehe... boostin' ghetto style. I love it.

zip

Ghetto style rules! I knew your idea had potential when you first posted it. Good job.

Sonny

Dude, you are the man!! I already have a Hondata, but it's good to know that this option is out there for the people who aren't running a standalone.

Sonny

FIxALPHA

Geoff,

I picked up the extra map sensor, and now looking for the Greedy black box. Hopefully this works. Damn...I can't believe I bought a $300 FMU (Vortech Super FMU).

Thanks

dbman96

The idea is, with the 2nd map sensor you wouldn't need the greddy black box - you can leave your current map sensor the way it is and hook up the 2nd map sensor anywhere you have a boost/vac signal and wire it to the TPS input on the VAFC.

FIxALPHA

Im looking at my extra map sensor right now....there are three wires. Which one do I hook it up to. Also, just take out the wire directy off the ECU (TPS input) and put it straight to the map sensor.

Thanks

VTC_CiViC

Yea I think if I do this I'm gonna go the extra MAP route too. Hey dbman I have a question, how do we know where to set the Hi throttle Lo throttle settings? I assume you'd find out whatever your voltage is a max boost (let't say your boosting 7psi, whatever the MAP voltage shows at 7psi find out what that equates too on your TPS and set that for Hi throtte) but see how do you set Lo throttle? Vaccum? 0%?

dbman96

I actually found this to be the most useful adjustment... I set the "lo throttle" to a little bit lower than it reads with the ignition on and engine not running (0 boost, 0 vacuum). So if my narrow throttle settings are like -40% give or take across the RPM band to make up for big injectors, I want -40% for almost all the time I'm in vacuum; then as I get to around 5" vacuum it starts gradually enriching my mixture as it climbs into boost. I believe the way my VAFC is calibrated right now is LO 60% HI 95% which seems to be very smooth transition in and out of boost and keeps it economical when you're freeway cruising at 80 mph and like 10" vacuum.

VTC_CiViC

Awesome! Let us know when you think you're done with it cause I'd say i'm pretty sold on going with a dual MAP version of the boost dependant V-AFC setup (like yours but with twin MAP's instead of the J&S)