Jason kiDD

Well after dyno pulls and tuning I decided to set back all part throttle settings
to zero and increase fuel at around 4.5k up to 8k at about .5 increments.. Prior VAFC settings were -5 at idle, zeroing out around 5k and increasing fuel to 8k.

I now get better gas mileage leaving VAFC settings at zero from idle till 4.5k than I did when trying to lean out the motor prior..

Your thoughts, aside from the fact that the ECU will automatically adjust to fit back into pre-map settings in closed loop..

Jason kiDD

Wow, no one responded?

Adam.

Did you do this with a wideband o2? If not, you are treading on dangerous ground.

Ministry

wierd. maybe you were leaning out with your previous settings and your ECU was overcompensating?

Jason kiDD

The lower negative vafc settings were mainly for anything below 5k and was on the part throttle settings and that netting me the 200whp you now see in the sig. Only thing the tuner did was bump the fuel from 5k upwards to around 10 points on wide open throttle settings only..

And dreamer yeah it would seem that at idle and closed loop operations the ECU will always try to correct the map settings regardless of what your VAFC is set to. Which makes me think its pretty much pointless until you are using the O2 sensor and/or Wide open throttle..

Ministry

honestly, I have come to believe that VAFC sucks. It's such a clumsy way to tune. My butt dyno always indicated that it was pretty useless at less than WOT, and your findings are confirming my suspicions.

Jason kiDD

I kid you not with prior setting I was getting like 150 to 170 to a tank city highway mix driving. And this is conservative driving not even heavy on the pedal..

How with settings set to zero at anything below 5k on narrow and wide throttle I am getting 200 to the talk city highway driving..

To me that is a big difference and the motor doesnt feel any less powerful..
Reminding everyone this is using 290 cc injectors at 42psi..

Adam.

The problem with tuning your VAFC the way you are is that you have no idea what your actual a/f ratios are set too.

Correct me if I'm wrong, but you can't tune the timing settings separately on a VAFC (or at all). Your a/f, outside of a major problem, will net you very little in gains. Tuning based on ignition timing is where you will see major improvement.

For the cost of pretty much selling your VAFC, you can be running uberdata w/ fully tunable fuel and ignition maps. You'll probably even come out ahead.

http://www.ecimulti.org/uberdata/forums

Find a tuner locally, have him set you up w/ a socketed ecu and then take it to a dyno for tuning.

Ministry

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jason kiDD &raquo;</TD></TR><TR><TD CLASS="quote">I kid you not with prior setting I was getting like 150 to 170 to a tank city highway mix driving. And this is conservative driving not even heavy on the pedal..

How with settings set to zero at anything below 5k on narrow and wide throttle I am getting 200 to the talk city highway driving..

To me that is a big difference and the motor doesnt feel any less powerful..
Reminding everyone this is using 290 cc injectors at 42psi.. </TD></TR></TABLE>

Like I said, I suspect that you're ECU 'thought' you were running lean and dumped extra fuel in there. I'm glad you noted which injectors you use. I had a similar problem a year ago. My mileage was shitty, even with a tuned VAFC. I was running 290's at stock (OBDII) fuel pressure, which I think is right around 42 psi, all on a p13 (OBDI obviously). I got fed up and switched to OBDI injectors (320 psi or something like that), dropped fuel pressure down to 30 or so psi. After dyno tuning, I'm making an avg of 27mpg (~260 mi per tank), and actually gained power.

I would consider switching to OBDI injectors if I were you. That is probably why you have to add fuel in high RPM, where I have to lean it out at high RPM.

Jason kiDD

You dont know how long I have been meaning to do so, what car is your setup in.. My tank is only 9.5 gallons in the CX hatch if that much so assuming that I get even 210 per tank I am still not that bad off at current settings..

I have a set of 440's that I am thinking of throwing in there, but not with the VAFC since in closed loop the ECU will constantly be trying to adjust itself anyways.. Maybe ODB I injectors are in order for now..


Modified by Jason kiDD at 12:33 PM 3/25/2005

Ministry

yea I got an EG CX too, so I'm happy with my mileage. I guess it comes down to the fact that you're ECU 'thinks' its running 340's or whatever OBDI is at ~30psi, when it is actually running the OBDII 290's at ~40psi. You can get away with it, but it seems to cause all types of tuning headaches.

I would consider OBDI injectors. You don't have to get RCs. I got remanufactured ones for cheap and they work fine.

Jason kiDD

The p28 I am using is already socketed and using an Age Engineering chip. I have long though of selling the VAFC and getting a wide band to do tuning but since I plan on going turbo down the road anyways I will just hold off for better all around Engine management..

Dreamer: If you can obtain me a set of injectors then I would try them out buying them from you of course..

Ministry

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jason kiDD &raquo;</TD></TR><TR><TD CLASS="quote">Dreamer: If you can obtain me a set of injectors then I would try them out buying them from you of course.. </TD></TR></TABLE>

I'll take a look around

Adam.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jason kiDD &raquo;</TD></TR><TR><TD CLASS="quote">The p28 I am using is already socketed and using an Age Engineering chip. I have long though of selling the VAFC and getting a wide band to do tuning but since I plan on going turbo down the road anyways I will just hold off for better all around Engine management..

Dreamer: If you can obtain me a set of injectors then I would try them out buying them from you of course.. </TD></TR></TABLE>

I don't know what your planned power output is, but I hear the dsm 450s are good up to about 300whp. Uberdata is enough for all but extreme turbo setups.