See the thread, I put the question in bold.
https://honda-tech.com/zerothread?id=305211
I think those of you who have Apexi VAFC might be interested.

 

That link points to the thread on secondary intake butterflies. What does this have to do with the V-AFC?

 

just to make this clear read the question I posted near the end. Actually hears the question, you my have to read that link to understand the thought process going into the question.

Ok one more thing.
H22Si you say the valves open up at 4900 rpms which sounds right, (cus in my helms the trouble shooting flow chart wants the mechanic to raise the RPMs to 5000 when check for no vacuum at that engine speed) so that seems accurate.
Now my question concerns Apexi VAFC. VAFC allow you to adjust the VTEC engagement timing through a broad RPM range. Can you also adjust the secondary timing also? Take the hypothetical. I get VAFC and adjust the VTEC engagement timing to 5000 RPM (which I would do and consider to be a safe point) Now the secondaries and the VTEC engagement point are really close to eachother, is that good or bad. Also is it better to allow spacing in between these system two engagement points?
Hmmmmm good question.........
E- to whoever can answer that with facts.

 

I have my vafc set at 5000 and the secondaries kick in just before vtec, ~4900 like you said. Yesteday, after reading your other thread I adjuster the vtec to engage at 5500 and the secondaries still switched at ~4900. My guess is that the secondaries work by air velocity moving through them, not an electronic signal. That explains why a vafc has no effect on them. Until I read your thread I didn't know what that noise was. To me it sounds like an echo to the engine note, much more subtlethan vtec though. As for causing problems by having them both switch close to eachother, since they are two independant systems, I don't see why they should have any ill effect on anything.


[Modified by piotrush, 2:24 PM 10/14/2002]

 

I haven't read my helm like the bible but I do vaguely remember reading something about the ECU signaling the IAB solenoid to signal a drop in vacuum pressure at 4900 RPMs thus allowing the IAB valves to open.

 

The ECU activates/deactivates the secondary butterflies. The solenoid is held to ground until 4900 rpm where it is allowed to deactivate and open up. Your VAFC does not control this, though you could control it using an RPM activated switch and a relay if you really wanted.

Gains to be had by controlling exactly when the secondary intake butterflies open are so minimal that it's not really worth playing with it.

 

my bad

 

nope its ran off vac. if u disconnet that vac lin of the IAB they will be open all the time. i have a dyno chart when i did this ifu wanna see it. i lost 7 hp from like 2-4k when i had them unhooked.

 

Ugh. Vacuum Solenoid 101

Vacuum is used to actually hold the butterflies closed. The ECU activates the solenoid which causes it to pull the butterflies closed using vacuum.

There's an electrical two wire plug going to the solenoid. If you disconnect this plug you will cause the solenoid never to activate, so they will stay open all the time.

If you pull the vacuum line, the solenoid will activate, but there will be no vacuum to actually do the work and hold the butterflies closed, so they will stay open all the time.

You might be thinking 'Ha, but when I mash the pedal and there's no vacuum, the butterflies are going to open even though the ECU is still telling them to stay closed.' No. There's a small vacuum box under the intake plenum that stores vacuum that the solenoid can use when there's no vacuum in the plenum. It looks exactly like the small plastic block box that you take out when taking out your CAI.

In short, it's really easy to get them open, and yes, the ECU controls the activation point of the secondary butterflies. When working properly, which should be all the time, the secondary butterflies will always open at 4900 rpm as the ECU deactivates the solenoid.

There are several vacuum solenoids in and around the engine that work on this same principal.

 

I got that understood hope you're "ugh" at me. Here I'll show you.
-When there is a Vacuum the valves are shut.
-The ECU signals the solinoid to activate the ground wire which releases the Vacuum thus opening the valves.
See

 

Sorry, wasn't ugh'ing at you. I was ughing at BoostedH23a1.

 

so if i were to drop my vtec to under 4900(were the secondaries open) would my car benefit from disconecting them so there always open allowing thecar to breath better with the earlier vtec??

i hope that made sense,


[Modified by 93h22a4, 9:59 AM 10/18/2002]

 

<<<<----------------CONFUSED

 

on my post or his?

 

uhhhh.... why are you reposting this ****, if you haven't gotten and answer yet, you're not going to get one.