EFI: How to Tune apex-i AVCR

This doesn’t really fall under the EFI Section so I’ll leave it here for now. The other thing is I will forget if I don’t write something down – lol

After talking with Rage2 www.beyond.ca and having him show me the manually settings it all makes sense after.


*DISCLAIMER*  Use at your own risk!

The manual really is written from an FOB’s point of view and even then I wonder if anyone really understands since it feels it was translated from a dictionary and not the actual meaning.

It took me some time to understand how to hook up the controller. The diagrams eventually made sense. As for the settings and tweaking I did the rookie setup of running the gear boost settings instead of actually setting boost duty (also cause I tried the self learning feature).

Boost XX
Duty  YY
Every Gear -/+ AA

XX would be the desired boost level you want
YY the duty that works for a gear
AA the amt you bleed off in reference to the gear for boost

If you like this method nothing wrong. Stick with it. For a bit more efficiency read below.

(1) The self learning feature – Works but is a waste of time to setup and requires a lot of patients and there is a slight risk you will damage your motor as you over boost (that how it learns). Technically the controller monitors boost and any dynamic fluctuations it *should* change.  I never had much luck and seem to over boost constantly so I share no advice in this section.

(2) Manual settings – a bit tedious but if you run the idea of setting low values and slowly going up it’s the safest way.
ie: Aim for XX boost but set the boost controller t o run -XX boost and slowly raise the bar until you get XX kg/cm^2

End Part 1

Closed Loop Boost setup

Ideally, you want the wastegate to stay closed – build pressure until it reaches the set point and then leak out constantly the correct amt as to maintain the pressure. Problem being nothing is constant or static.

For the AVCR you have to wrap your head a bit in thinking:

In any case, when you set the duty cycle, what you are really setting is the pressure that should be applied to the wastegate actuator to maintain the desired boost. So how does that relate to duty cycle?

The APEX-i solenoid valve is a three way valve. When voltage is not applied, the pressure line from the compressor is connected to the input of the wastegate actuator (forcing the wastegate open). When voltage is applied, the open side of the valve is connected to the wastegate actuator, allowing the pressure to bleed off (and allowing the wastegate to close).

As the pressure builds you want to maintain that level so the AVC-R has to switch the valve on and off rapidly. The amount of time it requires is that “duty cycle” for the valve to be open. At 50% duty cycle, the actuator sees compressor pressure half the time and releases pressure the other half. At 80% duty cycle, the actuator sees compressor pressure only 20% of the time. At 20% duty cycle, the actuator sees compressor pressure 80% of the time and the wastegate is pretty much wide open.

So, the boost trick really isn’t a trick at all (if you don’t get it re read the paragraph over and over) and recall what the goal is.

If boost exceeds the setpoint, the wastegate is not opening enough – decrease the duty cycle to let the actuator bleed off less pressure. If boost falls off after reaching the setpoint (or doesn’t reach it at all), the wastegate is opening too much – increase the duty cycle to let the actuator bleed off more pressure.

The manual has this equation that you can use to calculate – throw it away. It will work for your initial settings but it will not hold boost as you climb – nothing is ever static. There are many variables to come to play – not just the one calculation.

Which brings back to the fuzzy logic – Does it work? Yes, it does. Even though most people will cry foul (or say it’s a gimmick). The problem is that you  have to spend so much time in letting it learn and run variable RPM ranges that it can be quite harmful to the motor IMO. You also have to watch for spikes as you need to run 100% WOT. You have to pay attention and if your ECU can limit boost then your one step ahead! I did try to get this setting working but I found it frustrating to setup a base map. Since you need to run WOT for it to learn after you run the rpm ranges in low and it quite easy to boost past 1.20kg/cm2 (which would be way over boost for our application).

So why do it?
The benefit is that it suppose to adjust dynamic situations once you have a good base setting. Which has a lot of merit as you woud see turbo response increase for every RPM. The problems is it’s very hard getting a base setting – it takes time and lots of trials. Maybe in the next revision ther ewill be more memory for dataloging so it can catch the spikes.

So manual is what I have set – it under shoots the desired pressure as to allow the changes as air density does change so when there is a spike it won’t be hard. I’d hate to imagine if I was over shooting 1.20kg/cm^2 and not knowing.. haha

A small observation:
Small intercoolers I notice you end out leveling out the duty cycle to even a slight downward slope where you bleed a bit more boost way up in the rpm’s.
o spikes are slow and easy to catch

Large intercooler –  you start to see a U shape.
o spikes need to be controlled. – WTF did we just see 30 PSI…

I will post some Integra settings on the next thread to get anyone just started. If you have a local dyno like I do around town this is the best place to setup base boost settings – cheapest as well considering the alternative


« Last Edit: December 08, 2007, 06:08:18 PM by speedracer »

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