sirbunz

Swapping ecu's (as in just another s2k ecu that runs leaner from the factory) That’s what this was in reference to from the OP. If you weren’t aware the 00-01 ecu run pig rich and later in 02+ Honda refined the fuel curve and picked up a little power as a result. But as mentioned, doing that pales in comparison to actually effecting the vtec engagement, which is where 90% of the available power can be made on this motor (in the midrange) through a few simple bolt ons and fuel tuning, all of which can be done without a full aftermarket EMS. You took what I said and went on a rather left field tangent. Many track s2k with stock ecu successfully, but if you want to do some simple safe improvements to the stock tuning for the DYI guy, there are some good options, without spending thousands of dollars. Honda got it 75% right out of the box, you can get another 10-20% of refinement without running a full EMS if your sticking to NA, in my experience tuning S2k's.
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Maybe you missed this...

I have seen both early and later ecus, vafcs/neos, and fully programmable ECUs, all with data from the same sniffer, a couple with widebands ... the OEM ecu is pretty lean no matter which one. This was the determining factor in choosing another haltech for my streetable S2000. I can only explain what I have seen in person.

Sorry you feel my info was "left field," but it just might help someone who needs it though and I feel relevant. As for 75% this or 80% that , I have no clue how you calculated this. The stock S2000 is not track reliable. It will work, but I and some other local S2000 drivers have no problem overheating well prepared ones. I have seen many that have thrown a motor due to the reasons I mentioned. Despite this, in simplest/cheapest form, no ... you do not have to do anything to your car in order to track your s2000 except pass inspection. No worries though, you are right depending on how you wish to look at the topic.

-Marc

s2000ellier

My 01 runs low 12s AFR above 8000, not lean by any stretch

sirbunz

Sounds about right above 8k. My '03 stock was approx 12.2 at 8100 using a sniffer combined/compared with my Haltech wideband. Both ap1 ecus look like they go really rich at the top end.

EDIT ... 3kish and 6k ish are where the mixture raised my eyebrow. 5-6k always seems a mess. With mods, it gets worse. A simple CT CAI made both mentioned points jump over 14.

JUSTINTHECOASTIE

lol kpro's not that expensive anymore dude! You also have to ask yourself what FUTURE plans you have for the car.

OP, I only suggest ems as your other option because I thought you were dead set on not using it. Before I went kpro, I used a vafc2 with boomslang harness and enjoyed it. As stated above, you would want to have a test pipe with either options. Understand you can only subtract fuel and NOT add fuel with a piggybacks(neo,vafc, vafc2)

Apex1.0

So no one can comment on the benefits of the newer processor?

Maybe the VAFC is the right way to go. Is there a good tuning guide somewhere? What about data logging? Whats a cheap way to data log?

s2000ellier

VAFC 'tuning' is only for open loop (WOT) so don't worry about trying to tune closed loop.

You will need an AFR sensor to due any sort of tuning unless you rent a dyno that has a tail pipe sensor.

You can get an ODB2 bluetooth connector to your smart phone and observe how you are affecting engine timing by cutting fuel with a VAFC.

I suggest just get the VAFC and only drop VTEC, dont bother with the fuel tuning yourself unless you really know what you are doing. Dropping VTEC will give you the midrange bump you originally asked for.

Apex1.0

That sounds reasonable. I am running a test pipe. Is it safe to bump it down to 5k with no other changes?

Where did you see the extension harness for $99. Best price I saw was $150.

s2000Junky

A sniffer IF you can pick up a good read, shows .5 leaner then actual due to its pick up location so keep that in mind. A wideband sensor at the test pipe is always more accurate then a tail sniffer.

When you lower vtec of course you will run leaner, the ecu still thinks its running in primary cam and delivering that amount of fuel. This area from the new lowered vtec to the stock engagement is where the rev band will show the first signs of fuel enrichment needed, IF the current MY ecu and bolt on config isnt pig rich to begin with, sometimes the primary cam fueling is adequate for the modified engagement without any additional fuel required. I found this to be more of a case with the early ap1's. Never the less, an onboard wideband is the best way to know where your at, tune appropriately.

Apex1.0

So if I just lower the VTEC to 5k and drive it, am I looking for trouble?

s2000Junky

Yes that will be fine, considering your MY ecu and vtec lowering point. From 5-6k its a bit of a flat/dead zone and where the stock fueling runs rich, now if you were to lower beyond 5k id say start thinking about checking your afr and potentially getting some fuel enrichment depending on how your motor is breathing with any bolt ons, 4500rpm is a sweet spot and shows the most gains and naturally the most fuel would be needed there. 3500 - 6k is the typical vtec improvement point with TP, and from 4k to 4500 is where the mid range power peaks. From 5-6 k you’re getting some bump in power, but its not as significant as the previous 1000 rpm.