Aurex

The Vtec control settings as I understand work like this.

Lo-Hi - Non-Vtec cam to Vtec cam. I.e. Vtec Just kicked in yo. If going for a stock engagement set to 6000

Hi-Lo - Vtec cam to Non-Vtec cam. I.e. Ah, Shit, fell out of Vtec yo. If going for a stock unengagement set to 5800.

There are actually three settings below the above that can be chosen. They will be initially set to be off.

- Throttle % - If set to say 50% then at 6000 RPM and 50% throttle, Vtec kicked in yo.
- Airflow % - Similar as above except airflow.
- Air Pressure kPa - Similar as above except kPa.

With the NEO Vtec can be controlled very much like stock and there are a few options and combinations/requirements to be met before Vtec engages.

Just an FYI. I set mine up to be RPM and throttle % dependant.

s2kbfast

Ah ha. So 50% on throttle and what on kpa would you suggest?

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Aurex

I left the pressure and airflow options off. So my Vtec will be based on RPM and Throttle % (I have mine set to 70%).

I read that 70% throttle is when the factory computer goes from closed to open loop.

s2kbfast

So on the same vtec screen you set the throttle to 70% and left the pressure off?

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s2000Junky

On my 01 its about 34% closed to open loop, so when I ran one I set to 40-50%. My guess is its the same from 00-03. May have been raised 04-05 but I don’t know to what. You will get better mpg with it higher like 70%, but your not going to get as much benefit in power/linearity/roll on power. Obviously you don’t want vtec to come on in closed loop, but the closest you can get to the transition the better. Id say 50-60% at least is a safe bet. But you should be able to tell if your running a wideband, and anyone running one of these should be so they can street tune the car and keep it in tune. Waste of money to take to tuner on such an easy interface tuning device. Also there is no afr calibration from weather temp, so you will need to make some adjustments on the road periodically to keep safe year round anyway.

So anyway, If you are running a wideband, an easy way to tell where the closed/open loop transition is, is when you go from the idle/cruse 14.5-15.2afr sweep area to the richer afr map, that is when the ecu transitions. This is easy to tell as long as you have made no fuel leaning or previous vtec corrections(should dip into the 11’s or low 13’s depending on MY) Switch your vafc to throttle position monitor and match it up to your afr gauge and figure it out and then set the vtec engagement percent just above that transition by 5% or so to be safe so the computer wont freak out on you.

with just a TP, you should be able to lower vtec in the 3500-4200rpm range, and 35-60% throttle engagement. Again use the wideband and your butt to set vetc, if the transition is seamless without a jolt and the afr without any fuel correction doesn’t change rich or lean at your lowered engagement point, then you have nailed it, if it goes rich then raise it, if it still goes lean at transition then you can lower it more.

To note, the vafc does not provide fuel enrichment (even though some have reported some minor success which I still question) Point is its not reliable to count on. The area between the new lowered vtec and the normal 5950rpm engagement will run much leaner since the stock ecu is still only providing primary cam fuel map there, so watch the afr, if it exceeds 14afr you are running too lean, losing power or running to high a cylinder temp for no gains (13.2 afr ideal for max trq, richer for hp and cooler cylinder temp) an easy way to get around this is to add a mechanical fuel enrichment via adjustable rate fpr that replaces the stock one. By increasing fuel pressure you increase the fuel in open loop, wile in closed loop the stock ecu re learns and trims the fuel to maintain the stoic fuel target. Trim any excess fuel in open loop aka wide throttle) as you normally would via vafc in the areas of the curve needed as before, wile getting safe optimum fuel in the mid where you made your vtec correction.

This has been my own method in tuning with this device in years past when either NA or low boost supercharged. Hope this helps. Good luck all.

Aurex

This is very helpful. Thank you.

If you recall, I have an AEM adjustable FPR and fuel pressure gauge, based on PM discussions with you. I also have an Innovate LC-2 wideband with gauge. So I believe I am set.

....as for the OP, I am still learning and I believe that what s2000Junky has said is probably a good methodology for tuning with the VAFC and NEO.

CoolGuy094

I can't add anything further than what "The Godfather" S2000Junky has already said.

Just as a reference, here are all my Apexi Neo settings from when I was N/A. Mods are listed at the top of the first page. Use this info at your own risk.

s2kbfast

This is all very helpful. Thank u.

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