FastechAccord

did any one else with a V-AFC have problems with their vtec engagment point?? Mine is acting real weird and I need some help.

4doorH22

Sure you got the VTM wire right? What exactly is the problem?

John

make sure your connection is good as well b/c the V-AFC will get real unless the connection is soddered well...

FastechAccord

I figured out the problem, the vtec on my SOHC VTEC 2.2 kicks in at 2500 from the factory. I was under the impression the vtec kicked in at 5500 by the sound of the engine at that rpm. I couldnt figure out why the car ran so slow when the vtec engagment point was changed to 4000 rpms. So, anyone with a F22B vtec, you vtec kicks in at 2500.....extremely early, but if you have it kick in later, it runs like crap.

wizurd

2500 seems pretty low. Anyone have a source from which this statement may be true?

John

set it at 3500... i have the dyno charts to prove it's the best x-over... even Misa will agree...

Mark27

Yes.

I can confirm that the engagement point is indeed at 2500rpm. You can verify that by hooking up an led to the VTM wire of the ECU.

So that's why our F22B1 is not listed on the compatibility list on the VAFC page. We're supposed to use the SAFC...

SOHCArchangel

2500 is waay too low oil prees at 3000 is 50psi anything lower and the rockers will not cutover, not only that but you will make less power on the hi-cam that low

NO, I had vafc, and john, and a few of my freinds have it for the f22b1 it is compatable your not reading the manual correctly

EDIT: wait a minuite you cant set it lower than 3k rpms anyway , Whats going on here?


[Modified by SOHCkordVTEC, 7:15 AM 2/1/2002]

John

are you sure you have the correct setup configuration? something doesn't seem right here...

Nick M

There is no VTEC with a SOHC f series until 4200rpms or so. 2500? not enough oil pressure like Misa said.

wizurd

I can verify this. Not a good way to have found out....but I did anyhow. A couple of weeks ago my car was extremely low on oil. So, when I would take a corner fast, flooring it....my car would go slow...then around 4000 VTEC would kick in rather hard, kind of like an automatic, it was weird. And YES I know it was stupid of me to be driving like that with low oil.

SOHCArchangel

no 4k is to high, you want to set the x-over at the point where the low and hicam will make the same power so there is no jerking. mine was set at 3500 before my car got broken into and stolen

='( i miss my vtec

wizurd

I'm talking stock, no VAFC.

John

3500rpm = dyno proven for F22B1s

97accordex

The cutover point varies based on input from several sensors. If you have a factory manual (Helms) for the 97 Accord check out page 5-7.

Anywhere between 2300 and 3200 rpm depending on intake manifold pressure. Also depends on engine speed and coolant temp.

The ECM monitors the sensor inputs and kicks in the VTEC.

4doorH22

All hail the mighty VTEC.

wizurd

:bows:
Here's a pretty informative site all about VTEC and how it works if anyone wants to take a look at it who hasn't. http://www.leecao.com/honda/vtec/index.html

Conechaser

Great site I've had it bookmarked for awhile now and have read most of it.

Nick M

That is a very informative site. Im suprised i've never seen it before.

Bklyn TSi

Yes Mark27, I also have an LED connected to the Vtec solenoid positive feed and it does kick in somewhere around 2500 if gassed hard, if foot lightly on gas it will kick in somewhere around 3000... I always thought my car was weird for having vtec kick in that early.. now does this apply to all sohc vtec accords or just certain ones?

wizurd

How did you hook up this "LED"? What parts, wires, etc..
Thanks

Bklyn TSi

while mark tapped into the ecu, my wire ran through the firewall and tapped into the vtec solenoid, which is 5" cylinder next tothe valve cover. the green wire running into/out of it is positive and charges with 12v whenever vtec kicks in... at least that's what i've been informed by several websites... the other end i grounded the led and placed it in the dash cluster, but that's another story...

FastechAccord

DunReit, do you have any dynos you can post so I can see that i definately want to set my vtec up to 3500. If i move it up the car lacks alot of power down low. If I run my car thru autocross or any hairpin turns i would have trouble coming out of the turn if my RPMs dropped below 3500.

Mark27

I don't know if the signal change of the VTM wire at 2500rpm is the vtec engagement point. Because according to various manuals, it's supposed to be until 4000rpm

DunReit:
How can a dyno chart shows when vtec engages in sohc vtec engines? A sudden increase in horsepower doesn't mean there is a switch of cam profile. The engagement point is defined by a signal that's supposed to change in the VTM wire.

wizurdofawwz:
blue led from radio shack, then calculate the resistors you need to use, hook the negative side of the led in series with the resistors, then to the ground. The positive side of the led to the VTM signal wire.

I did it just for fun. I permananently hooked it up to illuminate my power window buttons now

John

if you compare where you set the VTEC xover on different dyno runs, you can see a huge difference... this comes from my experience with three different dyno tuning sessions over the past 2.5 years...

i'll post my dyno charts as soon as i can find a scanner to scan them in (my scanner broke)...