Hey guys, I'm having a problem with my vafc2. I installed it a couple of days ago and everything seems to be right. The throttle position is perfect, reads all the way from 0-100. There is one thing that is off though. The revs are off. Everything below 3,000 is accurate, but anything above that is really off. For example, my car will be at 5,700 rpm, but the vfac2 will read 5,000. What could be the problem. I would appreciate the help. Thanks

Raul

 

whats the tach read when you are at redline? our tachs are off pretty bad and you could possibly just have a REALLY bad one

 

my tach is correct, it hits the limiter around 6500, 6600, but the vafc2 will read like 5500

 

what are the settings you are using?

 

im using 1 in 1 out, up right arrow, and vtec type 1.

 

did you make sure to do the throttle learning procedure before you started the car the first time?

PS: is it a constant low value or does it get further off if you rev higher?

 

it gets further off as i rev higher

 

Did you use 6 cyl? And yes, these tachs are off something sick, and yes it gets worse as you rev higher.

See what your car cuts out @, and see if you can do a peak/hold to verify what RPM the VAFC is seeing when it cuts out(rev limiter)

 

if you havent gotten it yet, i have your solution:

1)initialize all settings (if you have corrections made, copy them onto a piece of paper first)
2)turn car off, then back on (no start!!)
3)set-up vafc BEFORE you start the engine
4)enjoy your vafc-II that now shows true rpm.


sorry to bump this thread, just wanted to make sure hes got it working

 

He got it last week some time. No worries.

 

i may or may not have had experience with this recently so just though i would make sure

 

There was never a problem wit ther OP's set-up. He just wasn't aware of how bad the stock tach was off. I ran him through a quick exercise (rev in neutral to rev limit) and see what values were seen. It was 6530, so that tels me there's not a problem.

 

yeah, i read the directions wrong and would hit initialize after i set it up every time. decided i would check what it said at rev limit...6130. i WTFed?!?!? for a few mins, then tried turning it off and setting it up again. much better now...verified at 6749 lol

 

Ya i did the same thing w/ the initialize feature. I would hit the rev limiter at like 9K rpm cuz it thought it was a 4 cylinder.

 

Highest stock A33B yet.

 

thought it was weird but meh, whatcha gonna do. 6650~6750

 

BTW, it was in neutral so it probly got above the 6650 fuel cut just from momentum...makes sense to me.

 

I wonder what it would do (WRT max RPM) on a dyno.

Mine never went above 6530 on the dyno, IIRC.

 

dynotune on monday...we shall see

 

does the vafc display the same as the tach? cause my tach reads about 6750 at fuel cut (pretty accurate for an a33b, i know) interesting that they would both be wrong though if not reading the same signal

 

My tach begins to read 'off' from 4k+, and just gets worse as the RPM rises. Verified that my SAFCII and OBDII software which both see what seems to be the same exact reading, whereas the tach is just off in comparison.

If you tapped into the proper signals, it should be fine, i.e. reading what the engine is seeing and not what that tach is seeing. When you dyno, you will see the results via runfiles since the signal is tapped on the CP.

Be sure to wrap only ONE wire from the CP.

 

lol @ wrapping more than one wire

 

Some shops wrap the entire thing, since there are 3 wires wrapped inside the electrical tape going to the CP. Make sure it's not even close to other wires because then your runfiles will be nearly useless when trying to compare RPM.

You'd be surprised as to how many A33B & A34 owners have that random signal loss in their runfiles.

 

ill have to make sure they know whats up. if a get useless runfiles after $100/hr ima be pissed. im already getting jacked

 

They're not completely useless. Only when comparing RPM they are.

 

well it would be hard to tune a vafc without useful rpm data

 

I'm guessing you have never experienced this, nor have 'tuned' using a VAFCII?

 

nope. never really even dyno'd before.

 

It's pet peeve of mine when I see missing #'s like this.

Like seen here: (Courtesy of 96sleeper)



What it does to the .drf is lose all tq #'s after that signal loss. So, say one wants to compare one dyno to another @ a certain RPM using the data vs the graph, it cannot be done. But it does nothing to afect power vs speed/time or any other parameter, JUST RPM.

 

those gaps...ugh. yeah that would annoy me too. wrapping one wire will be the first thing i tell the operator