I have my vtec set at 3800rpm. And when I'm cruising on the freeway way I'm at about 4000 rpm.

Would vtec only kick in under load or would this low vtec setting reduce fuel economy.

I haven't data logged anything yet or really looked this up.

Any ideas?

 

From my understanding, its only at a certain throttle position (whatever the tuner set it at) that your VTEC would kick in.

 

disregard, idk what i'm talking about.

 

The VAFC isnt sophisticated enough to operate vtec under load or oil pressure, it only operates by rpm engagement and bypasses all other OEM signals, so if your cruising rpm has exceeded the rpm engagement point at any throttle position, it will be on and MPG will go down. Your best option is to raise vtec to a point where you know you wont typically be cruising, or even shifting if you prefer. 4500-5k is typical rpm engagement for that compromise I found.

 

Nope, its only engaged by rpm.

 

Interesting. i was just searching through this forum to find an answer and everyone seemed to agree that it was based on oil pressure.

the more you know i guess. thanks for that.

couple links:

https://www.s2ki.com/s2000/topic/860...ec-switchover/

https://www.s2ki.com/s2000/topic/893...ec-kicking-in/

 

I actually think it has to do with throttle load and the ecu / ems. Some ems systems allow you to fine tune everything. Don't think it's all 100% correlated to the rpm spinnage.

If I do any datalogging down the road, I'll share it with the forum.

 

Both, depends on the tuner and how he set it up. There is a "vtec lower" and "vtec higher". Jeff Evans will set the lower to however low it needs to be, sometimes like 3500 rpm. Then set the higher to 5500 or somewhere up there. The pressure in the manifold will then regulate if vtec is kicked on or not. The lower number is the WOT vtec engagement point normally. The higher number is the "no matter what" vtec engagement point, it will kick into it no matter how much throttle.





I have my vtec at 4200 or 4300 right now, I forget. It allows me to go 129 before my vtec is forced on, which is reasonable really.

 

Both, depends on the tuner and how he set it up. There is a "vtec lower" and "vtec higher". Jeff Evans will set the lower to however low it needs to be, sometimes like 3500 rpm. Then set the higher to 5500 or somewhere up there. The pressure in the manifold will then regulate if vtec is kicked on or not. The lower number is the WOT vtec engagement point normally. The higher number is the "no matter what" vtec engagement point, it will kick into it no matter how much throttle.





I have my vtec at 4200 or 4300 right now, I forget. It allows me to go 129 before my vtec is forced on, which is reasonable really.
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Are you running a Neo or Vafc2? That's not how the vafc works and I would be surprised if the NEO is any different, but I cant say for sure since Ive never tuned a NEO. Did he modify/custom wire in the unit to have connectivity to vtec pressure switch or see manifold pressure?

On the vafc/vafc2 its still all rpm engagement based, its just the HI vtec setting tells it when to engage at accelerating rpm and the low setting tells the ecu at what rpm for vtec to disengage on decel, no matter what the throttle load is. For example, if you set vtec to come on/HI at 6k rpm on the vafc, but set LOW to engage at 4k rpm, then vtec would stay on the whole time you were driving around above 4k rpm, but as soon as you let the rpms drop past 4k vtec would come off and you would have to accelerate back up to 6k rpm again before vtec would come back on. So hi/lo only sets up the 'rpm window" of where you can be on and off the gas without disengagement. Typically you would run the Low setting to the closets rpm from HI cam which is in 100rpm increments (at least on the vafc2) so HI 4500/LO 4400 for example.

I ran and tuned one of these on my own car for years. Used it NA and then on a lower boost level SC. Its been a few years but I still remember its functions and quarks pretty thoroughly. Not many run them any more nor understand them fully if they do, so its likely getting harder to find sound information on them unless you go back a few years on some searches. If you go back too far circa 2000-2004 you will get a lot of software engineer brainiacs posing theories and adding a lot of typical convoluted information which can just add to the confusion of an otherwise very simple functioning device. There are a lot of other parameter functions on the menu of this unit which does nothing on the S2k though, which can add to some confusion to the new owner, but just simplify the tuning on the more well versed. There really is only 3 parameters you are effecting, Wide throttle AFR, VTEC rpm on/off and throttle percentage. Everything else should be ignored.

 

do we even know what the OP has?

vafc is only rpm based, aem and hondata you can do load based.