EMS

A few things are not completely clear to me about the AVC-R:

- If changing the start duty from 0% to eg. +5% in one gear, does that mean you disable the gear depending self learning function for that gear? Or does it disable the self learning function for all gears?

- If you keep the start duty at 0% for all gears, does the AVC-R use different (self learned) dutycycles for every gear, trying to achieve the desired boost?

Mark.

UkLegacyT

using a 0% start duty means that the unit will automatically self learn the gears.
if you change the start duty to any value other than 0% then the unit will go by that figure for that gear, and will not self learn.

bit of advice though, turn the self learn function off, as myself any many others have found it to be useless and results in boost spikes here and there, and that is on cars other than subaru too, inc gti-r's etc.

i found the best way to set it up was as follows:

1) turn learn gear function off by selecting the 'X' for all gears.

2) ensure all start duty values are 0% for the time being.

3) set the main duty cycle at say 30% across the rev range to start with.

4) now set the boost curve as desired on the boost setting screen, from 2000-7000 or similar etc. if you want 1.2 bar across the range, set it at 1.2 kg/cm2 for each rpm point. (kg/cm2 is apexi reading, and 1 kg/cm2 ~ 1 bar).

5) now you need to drive the car from low revs in fourth gear, then open the throttle fully until 7000rpm (if uk car) and watch the boost behaviour on the unit's boost gauge.

(for safety reasons , its best to get somebody else to drive it for you on a quiet road, then you can faff around with it and not worry about taking your eyes off the road).

6) now adjust the settings if required. say you had 1.2 kg/cm2 across the rev range, but at 4000rpm you got 1.3 kg/cm2 and at 6000rpm you got 1.1 kg/cm2 (only example).

now go to the main duty cycle, and at the 4000rpm rev point, lower the duty about 25%, at at 6000rpm increase the duty to about 35%.

now repeat the fourth gear run until you get your desired boost curve with no overboost/underboost...within reason...wont always be perfect.

tootle around a bit between runs though, as you dont want any high charge temps.

7) now do a 3rd gear run, you will find that due to the lower load on the engine, the boost will be too low.

if so, go to the start duty and adjust it to about +5% for 3rd gear.

then try the run again until boost is correct. do the same for 1st and 2nd gear, boost will be lower again due to load, so adjust start duty as needed for those gears.

then do fifth gear, load higher, boost higher, so start duty will need to be say -5%.

the above is only example, you may want higher boost at mid revs, lower at top end (charge temps high at high revs/boost) etc etc.

you will need to mess around with all of the settings to get it correct to how you want it.
and remember that fourth gear start duty can always be altered after too if the boost is too high or low, leaving at 0% initially just makes for a good base to set the boost up.

hope this helps...have fun
ian

UkLegacyT

also be careful what boost levels you use, 1.2bar was just an example, a knocklink is ideal if you want to up the boost a fair bit, or you may run lean and melt a piston.

EMS

Thanks Ian, setting the duty cycles is something I am used to for years with different boost control systems, but your (clear!) explanation could be helpfull for other people too!

I will try with the self learning function switched off.

If anyone else has different experieces, I also would like to hear it.

Mark.

Mr J

Ian your details will be most useful when setting up my AVC-R when it arrives


Jan

UkLegacyT

no probs guys, glad to help

Scott.T

iTrader: (2)

Are there any real gains to be had from ditching the standard Boost Control in favour of an AVC-R or similar ??

Is the TD04 physically capable of generating the boost any sooner.

If so I may look at getting one.....

dowser

Scott - disconnect the wastegate actuator feed hose and go for a drive to find out. Get off the gas at 1 bar though

Richard

UkLegacyT

scott, i think you'll find that the tdo4 is very fast spooling anyway, so doubt you would see any gains in that respect.

as for boost capability, same agin really, not much good with a tdo4. the tdo4 is a bit small for high boost, and if used at high boost, it creats very high charge temps as it overspeeds, meaning potential risk to engine internals etc.

ian

Andy.F

Thanks Mark

EMS

I don't like the RPM points are 500 RPM apart! For quick spool up I would like to use high duty cycles low down, but with the points so far apart the AVC-R isn't able to drop duty quick enough when the turbo spools. Overboost is the result. Therefore you have to compromise and reduce the duties low down to avoid overboost. (which hurts spool up!)

Is there a boost controller available with all the features of the AVC-R plus the adjustable RPM points?

Perhaps the new AVC-R which should be available shortly?

Mark.

Andy.F

Mark

I know someone who is using a Dawes valve in series with his AVC-R

If the Dawes is set to say 80% of target boost, it ensures there is no wastegate creep until this point regardless of duty cycle. The AVC-R is then responsible for fine trimming the boost to achieve target.

Andy

john banks

Mark, how about a Dawes device set to low boost off the compressor outlet to stop wastegate creep low down? I think Bob tried this and liked the results.

Scott, you can get a very nice boost profile on a TD04 with a Dawes. I got 1 bar at 2300 RPM with full decat with this setup. Tapers to about 14 PSI at 6000 RPM, with a midrange hump of 17-18 PSI depending on temperature and det etc. Bleed hole at 1.0mm gives smooth control - not too aggressive on part throttle to send it lean or cause compressor surge - at least not with the OEM dump valve, doubt it would with an aftermarket one either because the compressor map is so leftward biased.

john banks

LOL.

EMS

I never looked at the Dawes Device, but I will give it a closer look.......

From what i can remember vaguely from what I read long time ago, it bleeds all pressure to the wastegate until a certain (adjustable?) boost is reached and after that it has a adjustable bleed. Is this correct?

Mark.

john banks

It is a relief valve which is normally closed at low pressure. Higher pressure unseats the ball and allows pressure to pass to the wastegate actuator diaphragm. An adjustable length spring opposes the air pressure. So *NO* air passes until quite near to setpoint which kills wastegate creep. It is also very effective in lower gears, because say in 2nd gear with a TD05 it doesn't really open until 3600 RPM, whereas the ECU or AVC-R duty would have dropped to stop 3100 RPM overboost in 5th gear.

dowser

I'll also be trying the dawes inline - I guess it should work OK as it's open loop. It caused havoc when I tried it on the stock closed loop system a while back.

Richard

UkLegacyT

sorry about no reply to your question andy, not been on here since, thanks to work

i dont actually have the boost controller any more, but never thought of using a dawes with it. also, one thing i didnt like about having such a boost controller, is that varying egt and ambient temps cannot be compensated without altering the boost/duty manually, bit of a big really, especially when hammering it for a while.

ian

JamesS

I must disagree!

With the gear-learn disabled you are running open loop, based on the duty-cycle vs rpm table. Ambient changes are not taken into account.

The AVC-R on a td04 car will improve boost responce.

I found best practice is to leave gear-learn on in 4th and 5th gear and adjust the start duty in the lower gears.

When first fitted I`ve found the easiest thing is to set the target boost as required, then set duty cycle to 65-70%. Drive WoT in 4th gear to activate self learn. Do an idle to as-fast-as-you-dare run a number of times and bingo job done!

If you `guessed` duty cycle is too far away from the desired boost it will not home in on the `correct` duty cycle......

Changing the feedback speed has no effect whatsoever!!!!!

[Edited by JamesS - 8/14/2003 1:42:21 PM]

Andy.F

Hi Ian/Mark

When you have the self learn 'off' on the AVC-R does that mean you are running open loop control ? ie is the boost controlled by fixed duty cycles set up using 2 dimensional maps on the rpm/gear screens ?
If so, how does this cope with varying ambients/EGT etc ?

cheers

Andy


[Edited by Andy.F - 8/12/2003 2:38:14 PM]

EMS

Andy,

It is still in closed loop when the self learning is disabled! The self learning only changes the base duty cycles. You can switch off closed loop also by reducing the F/B (feedback) speed values.

Mark.

[Edited by EMS - 8/12/2003 9:12:10 PM]

AlanG

EMS wrote:
Hmm..I'm wondering about this as well. and am looking for clarification.
You only have one duty cycle screen which gives duty cycles fot that particular setting, for example, setting "A". Yes?
Surely there would be different duty cycles for each gear due to different loads on the engine, in which case the unit would be learning constantly and never settle at the ideal DC's for say setting "A".
What i'm saying is, if you run your car at its limit (boost, AFR, timing,temp etc), then you can run the risk of doing damage to the engine because if for example you drove on full boost in 3rd gear mostly, but on the odd occasion you go full throttle in 4th, what's to say you end up overboosting in 4th and blow the engine (due to weak mixture, too advanced timing) because the AVC-R has been "self learning" in 3rd gear?

And finally...

EMS also wrote:
Ermm..on mine you can change the step size? i.e. 500rpm, 1000rpm etc?

Alan

EMS

Alan,

Some time did pass and I did setup quite a few of those AVC-R now. It depends strongly on the setup of the car, what will be the best setting. I did a few cars with self learning on in all gears with perfect results! But this doesn´t work too well in others.... Most of the time I choose for selflearning on in 4th gear and postitive start duties in 1,2 and 3 and negative in 5th.

Mark.

AlanG

Thanks Mark

The other thing i wondered about was this:
Would you not use feedback for the partcular gear to stabilise the boost and reduce any tendency for boost spikes?
Is the feedback facility any use?

Alan

STi M'8

Hi there,

I found out the self learn very useful on my v.8 when I set it permanently O in 4th gear (with corresponding start duties, as described by Mark):

As this function is correcting (not rebuilding) the "last learned" base duty map on full throttle, I get re-ajusted duty cycles/boost target every time I floor it in 4th (i.e quite often )...
Another good thing is that this intermediate gear will let you learn up to the RL, in less distance than same in 6th
(Yep! If you don't need your driving licence any more, you can even reach RL in 6th... boost speed limiting has gone )

This "active learning" has been a great improvement on my car, avoiding boost spiking and even higher steady values when climate goes to much colder air, low barometric press. etc...

Andy.F

Yes, it is the correction rate or 'gain' setting with regard to the action taken by the solenoid when an over/underboost target situation arises.
Generally setting this higher numerically in the lower gears is appropriate. This is because you fly through the zones quicker and there is less time for correction, hence the need for a quick change rate. In the higher gears, setting to high a feedback value can result in hunting as it overshoots and undershoots the target boost so it is appropriate to run a lower value.
Get someone to drive the car and you watch the duty cycle output WRT boost pressure, you should see clearly if you need to increase or decrease FB.

Did you try the start duty increases in the lower gears that I suggested ? I had a car in recently that we used this to good effect on. It arrived running 1.5 bar and left running 1.5 bar but you wouldn't believe it was the same car through the gears !!

Regards overboosting/timing problems, I always map these areas rich and slightly retarded then there is no problem, the overboost on it's own for short periods does no harm, in fact it can be turned into a worthwhile gain in the lower gears especially as a means to reduce the turbo rpm dip during gearshifts

Andy

AlanG

Andy
I wrote your suggested values down but then lost the slip of paper they were written on and couldn't remember what they were!!, so...no, i haven't tried it yet.
Any chance of you dropping me a mail with suggestions to refresh the ol' grey matter? Cheers.

Good point on mixture/timing. I don't run into the last row on the Link ECU with my present boost target, but is mapped to be richer with retarded timing just in case.

The first time i played with boost control on the Apexi, i homed in on target boost pretty quickly in 3rd,4th,5th, but 2nd gear would reach anything from 1.6-1.7 bar boost which as you can imagine, feels quite nice.

Alan

Denmark

iTrader: (2)

Alan,

Just leave at that,it must be great


i look forward to get a AVC-R myself.


Skassa

Mr J

Andy would you mind mailing me those setingyou used on on the AVC-R to..please

Jan

EMS

Settings do depend quite strongly to the setup of the car! But you could use this as a start (gears 1 to 5):

F/B speed: 5, 5, 4, 3, 2 (I did not have to use higher values, only lower!)
Start duty: 10%, 6%, 2%, 0%, -2%
Self learning: x, x, x, o, x

Mark.

[Edited by EMS - 12/29/2003 4:22:15 PM]