I just ordered an AEM UEGO wideband and gauge setup for the lude and I plan on doing some street tuning myself. For tuning I have a VAFC II, which is obviously extremely easy to use. I do intend to have my car dyno tuned in the near future, but I'd like to have a decent base for them to start with so I can spend less time on the dyno. So I have a couple questions before I get started;

1)What should I aim for as far as a safe a/f ratio? I know on the dyno from what I've seen mid 13:1s are ideal for a street driven N/A car, but would It be safe for me to aim for this being my first time street tuning a car?

2) Right now I have my timing advanced to 17* if I remember correctly (first thing I did to the car back in 04 ) I've heard that changes made to the VAFC II effect timing, so does adding fuel advance or retard timing? And leaning fuel out? Would I be best off setting my timing back to stock before I start tuning?

3) Any advice for tuning methods? I also have a G-Tech pro which I feel might be useful during all of this in one way or another, not too sure tho...

Thanks in advance for any replies to my long *** post

 

VAFC does not alter timing. This is the weak point of this. Even if you add/take some fuel, timing will remain the same.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pentaq &raquo;</TD></TR><TR><TD CLASS="quote">VAFC does not alter timing. This is the weak point of this. Even if you add/take some fuel, timing will remain the same.</TD></TR></TABLE>

I know you can't intentionally alter timing, but I've heard that as a side effect of it being a shitty piggy back controller that it does alter timing when drastic changes are made due to the lies that it sends the ECU. Thanks for the answer hopefully what you said is true. Can anyone confirm that timing isn't altered whatsoever when tuning with a VAFC? It would make me feel a lot better if that's the case

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pentaq &raquo;</TD></TR><TR><TD CLASS="quote">VAFC does not alter timing. This is the weak point of this. Even if you add/take some fuel, timing will remain the same.</TD></TR></TABLE>

the timing does change. Remember that all you are accomplishing with a VAFC is altering the MAP voltage, it's measurement of how much air is entering through the throttle body. The map sensor, along with other things, help determine ignition requirement and fuel requirements. When you make a change in the fuel, you are also making a small change in ignition.

to the OP:
Honestly, you could just street tune the engine to 13.1-13.4, somewhere in there. Then set vtec to whatever gives you the smoothest crossover. Get on the dyno and pay for three passes. That should be all the runs you need in order to make the crossover perfect.

 

pentaq and 98vtec are both right depending on which way you use the VAFC.

if you hook it up to just toy with injector duty then your only changing the fuel going into the cylinder

if you hook it up using the map hack then your changing the amount of fuel and timing by tricking the ecu into thinking the car is at a different load cell

just thought i would clear that up. there are MANY vafc hacks that are out there. got to know which way you want to go. search in the FI forum for the word "hack" and it should show up witht he most popular

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">

the timing does change. Remember that all you are accomplishing with a VAFC is altering the MAP voltage, it's measurement of how much air is entering through the throttle body. The map sensor, along with other things, help determine ignition requirement and fuel requirements. When you make a change in the fuel, you are also making a small change in ignition.

to the OP:
Honestly, you could just street tune the engine to 13.1-13.4, somewhere in there. Then set vtec to whatever gives you the smoothest crossover. Get on the dyno and pay for three passes. That should be all the runs you need in order to make the crossover perfect.</TD></TR></TABLE>

Great! Thanks a lot for the reply, thats just what I was looking for I'll let you guys know how it goes