AVCS intake cam advance angle

[joegoi]

Hi all,
I been tuning the rom for a while.
And successful in the boost target , inital and the max wastegate too.
The car is able to hold the boost all the way.

For beginner, the boost target try to increased at the beginning of the TPS range spool will be fast but driving around will be jerky if that percentage of TPS is touch.
This is from reading the maps of all the guys that have posted. CHEERS

So have anybody got success in doing the AVCS map?????
I have try advancing at the beginning with 2 degrees at about 1.2 to3.4 engine loads and 400-5600, not much of a difference compare to the target boost.
I have read from everywhere that to do the AVCS will need a dyno run.
So maybe that is where we can only feel the differences??

[Freon]

You'll probably need a dyno to really tell how much advance you need, just like timing.

[joegoi]

Thanks freon,
I think that is the only remaining choice that we have for tuning this map.

[swifty]

Can't it be done with a road dyno ?

[Freon]

Technically yes, but you may be looking at very minor differences. A road dyno is not going to be as repeatable.

[fasterthanurwrx]

In about two weeks I'll have access to a dyno for the entire day...

I plan on loading on a base stage 2 map for my 05STi and playing with it..

If theres any avcs maps you want me to play with I can flash them..then post results.

Let me know

[joegoi]

That will be great.
I hope that you can post the results on the finished dyno.
05 sti but my is a 04 sti and to edit the rom.
I need to use 03-04 wrx.
Is that the same as yours????????

[mrhp]

yo just got a cable and started tuning with it takes quite a bit to get your head around when you are use to tuning an after market ecu and figure out how things are labled ect but any way thought i would give you some tips after spending many hours with motecs and rally cars
with the avcs timing you basicaly want more advance down low and retard towards the top end rpm wise and when you get timing right the boost pressure will probablely be lower because of better volumetric effi with the same duty cycle on the waste gate and on road car you prob only get a gain in bottom end timing is good in the top end so you might be able to get right on road if you no what you loking at in login dont be scared to give heaps more timming 2000 to 4000 but you will take a while to get mixtures right and ignition as will be quite diff

[fasterthanurwrx]

Thanks for the info..

[swifty]

I've read the threads over on nasioc which are interesting but don't really explain things such as the impact of changing avcs on fuelling and ignition so I have dumped out my thoughts and questions below. I would like to get a better understanding of AVCS before being able to think about tuning it, but I also would like to know how my current default map affects things.

I may be wrong but expected to set AFR at the start of tuning with stock settings. Once this is set this should stay constant as long as I don't max out the injectors or fuel pump.

When the AVCS map is advanced it gives a greater overlap so the incoming mixture has the effect of helping to push out the exhaust gases and speeding the gases up. Some of this incoming mixture may also go out of the exhaust valve and burn (or not burn) in the headers. This should all help to improve the spool of the turbo.

If my car already has AVCS advanced at various points in the map then doesn’t this mean the afrs I’m seeing on my wideband are already not representative of the in-cylinder afrs because it is already possibly pushing some of the charge through to the exhaust ? If that is the case then at the start of tuning shouldn’t I set the AVCS map to zero before setting afrs ?

Given that some of the mixture may pass through and burn (or not burn) in the exhaust it will change the AFR that is seen by the wideband. However, as the maf sensor is used to determine how much fuel to inject to meet the target AFR, isn't the actual AFR of the mixture inside the cylinder is the same as it was before any changes to the AVCS were made ? The AFR seen by the wideband will be either leaner or richer than the actual AFR in the cylinder.

mrhp, are you saying that we will need to adjust the AFR after changing AVCS maps ? If so please can you explain why and what changes you recommend, richer / leaner / make it the same as before any changes were made etc. I guess that if your AFR goes richer then this means some of the charge is going through to the exhaust and not burning, or if it goes leaner then it is going through and burning in the header along with residual fuel from the previous combustion cycle.

OK, so I have dumped out enough on fuelling and AVCS, on to ignition.

If I start with zero AVCS advance and set ignition timing then start to advance the AVCS, will I be able to run more timing or less ? I am suspecting more because the incoming charge will be cooler than the residual exhaust gases and getting rid of more exhaust gas or moving it out of the cylinder quicker will have a cooling effect, so this will allow more timing with less chance of detonation. Is this correct ? Improved VE should also allow more advance.

Sorry this post is so long, I hope that any answers will help a lot of people on here.