the A'PEXi AVC-R
Before we can start programming the AVC-R we need to understand
what the duty cycle does. Without going into the theory behind wastgate
operation here is basically everything you need to know about setting
the duty cycle.
Increasing duty cycle increases the length of time that the wastegate
remains closed. If you are exceeding your desired boost level than
reduce the duty cycle. If you are not achieving your desired boost
level or boost falls off after reaching the set point than increase
the duty cycle.
The AVC-R's duty cycle is a very powerful tool. You can actually
increase spool up with this boost controller.
Setting desired boost levels
Using 3rd gear set the boost level to .68 (10psi) and the duty cycle
low about 30%. Slowly increase the duty cycle percent by 5% until
the desired boost level of .68 is reached. Once your desired boost
level is attained the duty cycle will be set. Now you can set the
final boost level. Double check the boost level matches the final
desired level by using third gear and punching it from about 3000rpms
to redline. If it overshoots or undershoots by a lot make slight
adjustments to the duty cycle as necessary. Small variation is acceptable
don't spend all day trying to get it exact.
Once desired boost levels are attained put stars in the duty screen
to begin self learning. I recommend that you use the self learning
mode for duty cycle because it will create a custom duty cycle curve
that will decrease turbo spool up time. It should only take a few
runs for the AVC-R to learn but double check by looking at the duty
The AVC-R MUST be set on rpms and NOT injector duty cycle or it
will not learn.
Gear based boost
In order for the AVC-R to identify gears, a gear judge value must
be entered for each gear. These numbers can be set by:
Having the gear judge setting screen displayed
Driving the car at 3000rpms in first gear
Once you reach a steady 3000rpms push the > key to set the value
Repeat for gears 2-5
My values for a DOHC transmission:
The numbers are not as important as the actual relationship between
them. This is how the AVC-R judges gears.
Make sure that all of the start duty numbers are set to 0% for
all gears/rpms otherwise the AVC-R will not go into self learning
Once all the settings are entered and you have allowed the AVC-R
to create a custom duty cycle based on your turbo setup you can
adjust the start duty.
Here is where the magic begins. The manual states, "Higher
start values will make the boost pressure levels higher." Translated
into understandable English, a positive start duty value will increase
boost while negative numbers will subtract from your desired set
boost. If you desired boost level is 10psi and you set the start
duty cycle to -30% in first gear than your maximum boost will be
reduced to 7psi in first gear only. To help with traction in first
and second gear subtract start duty from those two gears, the rest
of the gears you can leave alone.
Below are some settings that you shouldn't need to adjust.
The manual states that you can set the engine RPM point to control
post pressure. This feature doesn't interest me since I want to
control boost by gear. I'm not going to adjust this setting.
Again the manual states "If unstable boost or boost drop occurs
during boost control, the feedback speed setting may be necessary."
I'm not going to use this setting either since adjusting the duty
cycle is a more precise method of adjusting boost control.
1atm = 14.206
1psi = .9664Kg/cm^2
The AVC-R is overkill for any Saturn running less than 275whp.
This electronic boost controller is used primarliy to reduce boost/power
in the first two gears of a traction limited FWD car. If you are
not interested in building a 300whp+ Saturn than stick with a manual
forum has become one of the best resources for Saturn performance
on the net. Our members are constantly pushing their cars to new
performance levels. So, log in, share your ideas, and help push
your car’s performance to the next level.
August 2005 TSN will be holding its first ever meet
in Chardon, Ohio. Some of the fastest Saturns in the country will
be attending. Activities will include drag racing, dyno, tech session,
and BBQ. Look for the latest information in the forums.
Jeff and his team Different Racing have big plans
on breaking into some really low quarter mile times this year. Last
year he posted a 12.40 on a pretty healthy nitrous shot. This year
he has a new turbo setup and some serious determination. Visit his
website for the latest news and information. I expect we'll be seeing
some low 12's from him by the end of the year.