AVC-R Over shooting

[youngsyp]

I need some help on this if possible. I have set the AVC-R to run on 0.95 kg/cm2 for now. I have set the duty to 40% and have switched off gear learning so, have it running basic boost control. It is in self learn mode but, the boost over shoots. This morning it peaked at 1.03. Before I turned it down to 40 % from 45 % it peaked at 1.10 whilst winding up an R32 GTR. Why is it over shooting ? Is it because I have set the duty cycle too high ? I have also noticed that it will not hit 0.95 all the time. Sometimes it will only get to around the 0.80's ! Are there any settings I am missing ? I have checked and double checked and everything is set as the book says. I was expecting the AVC-R to hold whatever boost I set it at all day long with no fluctuations !!

Please help.

 

[JIMMYBACK]

i am having the same problems...................is there something we missed or are we being stupid?

 

[Davey]

have you still got a top mount?
Does it struggle to reach boost in hot weather/after sitting in traffic?
My theory (FWIW), is that the avcr knows what duty to use for a given atmospheric pressure, but when that pressure changes suddenly, because of hotter/colder day's (as it does a lot in this country), then it has to recalculate 'on the fly', if you look at it, you will see that it does pretty quickly increase/decrease to the desired level
my avcr seems to hold boost slightly better with my front mount fitted, but it rarely stays at exactly 1bar all the time.
If you look at it whilst driving, you'll probably see that it's over boosting for a split second only, which shouldnt be a problem.
You could try lowering the duty, but this wont help the fact that it doesnt always hit .95kg.
Also, try increasing the speed feedback, as this may help.
Also check for boost leaks

 

[youngsyp]

What you have said about the front mount makes me think about the length of the vacumn line. I may see if I can make it a bit shorter or at least make the lines coming off the AVC-R actuator the same length.

I will check the display when boosting to see just how long it goes over the set boost for. As you say, it can't be for long ! I was thinking of playing with the feedback speed. Do you know if this is like a gain control on the Prospec B2 or SBC Blitz controller ? I think this is what will effect how quickly it gets to the preset boost ?!
When I say it doesn't always hit the preset level I mean, when I put my foot down it doesn't always get there. If I gave it long enough, I'm sure it would.

 

[Curtis]

The length of the tube will only effect the amount of time it takes to react to a spike.
How long has it been learning for and have you only just started to use the car after a drive in very hot weather?
My vacuum tube is only about 10cm long as I have fitted the pressure sensor to the left strut tower and ran the line to one of the free nipples in front of the injectors.
You may need to get into 5th gear as fast as possible ie. still only doing say 30-40mph in 5th and keep your foot to the floor for as long as you can. Do this a few times and it should learn your required settings.
Remember, if you drive the car in hot weather, then don't use if again until a very cold day it will spike until it learns the new conditions.

Also check the filter in the pressure line (hold each end and pull apart gently, if it moves apart at all bin it!) as it's cr@p and falls apart. I removed mine after it caused massive spikes and then would not hold any boost!!!

 

[youngsyp]

My pressure sensor line is very short. The pressure sensor is on the firewall by the plenum. Probably about as long as yours.
Sounds like it is still learning ? I have only driven the car twice with these settings with only 2 or 3 times really hoofing it. Looks like I need to give it more time to learn

I will check the inline air filter though as it does seem a bit flimsy

Is the feedback speed similar to a gain setting ? I.e. will it speed up the reaction of the solenoid and help the turbo spool up quicker like the gain control on other EBC's ?

 

[andygtir]

the duty can be adjusted at different rpm points, to get it to hold boost perfectly.

just take it for a good thrashing and itll learn.

 

[Curtis]

the duty can be adjusted at different rpm points, to get it to hold boost perfectly.

just take it for a good thrashing and itll learn.

This is true, but it's better to let it learn them for itself otherwise it will think you know what your doing and rely on your settings and not learn...

If you've only driven it a few times then I'm sure it's just a case that it needs to learn. It will spike a bit until it settles down that's why its best to get it into 5th ASAP but at low speed and keep your foot to the floor that way it will build up to your requested boost slowly and settle quicker. If you floor it in say second it can spike so quiclky that it can take longer to settle and learn.

I think you have to be at something like 80% throttle for 20 seconds or more for it to learn.
try and find a long steep hill or do a bit of left foot braking or you could find yourself doing 150mph up the M1. :lol: :twisted:

 

[celm]

lower your start duty for that gear

 

[youngsyp]

Thanks for you help chaps.

It needs to be at 85 % throttle or more with a steady boost level, then it will start to learn.
I have to say that this is quite hard, as you guys say, the best way to do this is with plenty of load. So, into 5th you go and floor it :shock: Only problem is, is that you need a fairly long piece of uncluttered road. Luckily enough, I only had to hit 105 bananas to get it to self learn It seems to be settling down now so, looks like I was being hasty Car feels nice and smooth when the boost comes in. I need to find that R32 GTR to frighten again :twisted: