ST185 3SGTE boost controller queries

[Lanius]

Can anyone please explain to me what the duty cycle in a boost controller applies to? I'm assuming its got something to do with how much fuel is being put through?

I'm currently running an Apexi boost controller with 2 modes available (I have assumed this is for high boost and low boost settings). I've got the high boost setting (mode b) set to 1.1bar with 80% duty cycle. I'm not running this mode atm as I suspect there is an air leak either in the fmic or the piping for it - new i/cooler is on the way soon.

I've just set the low boost mode to 0.75bar also at 80% (it was previously on 50% duty cycle). The drive *feels* a lot smoother now than when it was on 50% ... is this just my imagination?

The car also has a piggyback fuel computer which I haven't even STARTED playing with yet (was tuned by TP about 6 months ago). Don't want to even touch it until I've properly learnt what I'm doing with the boost controller.

Cheers for any help ...

[anthonym]

Can anyone please explain to me what the duty cycle in a boost controller applies to? I'm assuming its got something to do with how much fuel is being put through?

I'm currently running an Apexi boost controller with 2 modes available (I have assumed this is for high boost and low boost settings). I've got the high boost setting (mode b) set to 1.1bar with 80% duty cycle. I'm not running this mode atm as I suspect there is an air leak either in the fmic or the piping for it - new i/cooler is on the way soon.

I've just set the low boost mode to 0.75bar also at 80% (it was previously on 50% duty cycle). The drive *feels* a lot smoother now than when it was on 50% ... is this just my imagination?

The car also has a piggyback fuel computer which I haven't even STARTED playing with yet (was tuned by TP about 6 months ago). Don't want to even touch it until I've properly learnt what I'm doing with the boost controller.

Cheers for any help ...

Hard to say without knowing the specific model of boost controller, but I suspect it may be a model that monitors injector duty cycle, and cuts boost when the % injector duty cycle you select is reached. The only other thing it could be is a direct reference to the duty cycle of the boost control solenoid but this is unlikely.

[Lanius]

If I remember correctly, its an Apexi Super AVCR (I think). Need to check it again to be sure ... don't know if that helps
[edit]Did have a couple of questions posted, but Google has come to the rescue [/edit]

http://www.ecanfix.com/~mdhamilton/dutycycle1.html <-- this is what you were talking about, correct?

Also managed to find this http://toyotaperformance.com/airflow.htm which I found very helpful indeed ... although filled with quite a few acronyms that took a bit of guess work to figure out

"Duty cycle refers to the amount of time an injector is held open vs. the amount of time available at a certain rpm before the next injection event happens and is expressed as a percentage. The electrical characteristics of injectors make it undesirable to drive them at 100% duty cycle due to heat distress on the injector windings and drive circuitry"

Cheers for your help, Nem

[anthonym]

If it's an AVC-R with the big flouro display the duty cycle you are referring to is probably the boost solenoid valve duty cycle. I'm not really familiar with this unit but you can download the manual from here http://www.apexi-usa.com/documentation.asp . Note it can also monitor injector duty cycle as well, but from a brief skim through the manual it's unlikely that this is what you are talking about.

[andrew]

The duty cycle on an AVC-R controls the amount of time the wastegate stays closed. The higher the duty cycle the longer the wastegate stays shut.

You should set the duty cycle as high as possible without it over boosting for quicker spool up.

IME it can be quite difficult to get the AVC-R to stick to a set boost level. You need to play around with the duty cycle and the self learning features quite a bit.

[Lanius]

Thanks for your help guys.

Its definitely not the AVCR with the fluoro display ... this is my one here --> (sorry about the size, its the only pic I could find).

And yes, this boost controller does spike a tiny bit. I've got it set to around 9 - 10psi, but it'll spike up to around 11.5psi before settling back down to 10. Duty cycle is set to 80% for both high and low boost settings. Not sure about the self learning settings ... the manual I've got for it isn't very specific about any of the more complex parts, just details how to set the boost level and duty cycle settings.

[andrew]

I've only used the fluoro display model and IIRC it was the first model with self learning. I could be wrong though.

I'd say try lowering the duty cycle in 5% increments until the boost spike disappears.

[Lanius]

Yeh I'll give it a go ... previously the spike was only noticeable in the higher gears (4th and 5th), but since dropping the boost and raising the duty cycle back up, I've noticed it in 2nd and 3rd as well.

Have hit boost cut twice in 4th on a very cold night ... left me on the side of the road wondering wtf happened before I figured it out. Thank goodness the car started again (eventually) both times. Had it set to 1.1 bar both times, and only found out afterwards that the factory ecu cuts at 16psi Serves me right for not doing my research

I'll try dropping the duty cycle back down to about 70 or 75% and see if that fixes the boost spike (although the boost spike doesn't really bother me when the boost is set that low).

Cheers man