View Full Version : boost control solenoid-tech info req'd
ibizacupra
17-09-2006, 16:07
I am looking for an uprated but stock ecu compatible N75 type solenoid valve. I think my new high boost levels are too much for the stock N75...
31hz 12v on:- http://www.aempower.com/images/products/30-2400.pdf
or this one but no spec on it:- http://www.jscspeed.com/index.html?/univ/boostcontroller/perrin_ebcs.htm
anyone got info on something like the jap boy big tuners would be using?
got to be stock ecu compatible.
thanks in advance.
mines gone to im only hitting 15 psi and have been for the last couple of months maybe worth uprating it with bigger and better even though it would be comlete over kill on my set up.
cupra_matt
20-09-2006, 18:14
Bill, i looked into the control range of the Apexi and it will control up to 3 kg/cm2 which will be ok for your monster.
john banks
27-09-2006, 16:06
The main electrical consideration is to consider the load capacity of the ECU's solenoid driver. To be safe you need to look for something that has a similar or higher resistance when you check it with a voltmeter.
The main pneumatic consideration is that it is a 3 port device of sufficient flow - a 3 port can work as a diverter rather than a bleeder. The usual connection with an internal wastegate is to connect common to the actuator and then Normally Open to the turbo compressor outlet and Normally Closed either to atmosphere or recirculated into the inlet pipe that feeds the turbo compressor. This way you can completely divert all the boost pressure away from the actuator diaphragm and effectively have the diaphragm seeing only atmospheric pressure (or a bit less if the NC is connected to the inlet pipe). The only thing then that will limit your boost will be the exhaust manifold pressure opening the wastegate. Consider the relative surface areas of the acutator diaphragm and the wastegate "penny", and the relative lengths of the actuator rod and the bar that goes to the wastegate penny - as well as the wastegate spring.
Usually it is a compromise even with an external wastegate in setting the wastegate spring(s) to get you at your lowest ever desired boost level, and then have a good 3 port to get it up to at least your highest boost level in the lowest gear you desire it to hit/hold on a warm day. Then the electronics have the necessary control bandwidth to do their job.
ibizacupra
27-09-2006, 16:42
nice info John.
you experienced any issues from a 3 port boost control valve and higher boost levels? (>2bar)
john banks
27-09-2006, 16:56
No, they are leaps ahead of 2 port bleeder setups.
The Evo IX uses a cheap method of 2 x 2 port solenoids LOL. I suppose 2 ports are safer as the failure mode is still OK if you have the restrictors sized correctly. If a 3 port fails stuck in the energised position you could get silly boost. Never seen it happen though.
john banks
27-09-2006, 17:07
Is the N75 able to disconnect the actuator from the boost pressure entirely when it is energised?
ibizacupra
27-09-2006, 18:29
If a 3 port fails stuck in the energised position you could get silly boost. Never seen it happen though.
I had this late last year... faulty N75 and uncontrolled boost at times.
I dont know about if they block when energised... need to check.
port sizes also a factor in control too.... along with PID in the ecu.
:think:
Just a thought, Would it not be possible to use a standard N75 to control A-Nother valve that had the capacity you require?
Like you would use a relay for high current applications with low current control?
Gavin
john banks
28-09-2006, 16:51
You could take the electrical signal that is destined for the N75 and then use a power transistor to drive a meatier solenoid. I have had success using TIP122 Darlington to switch the ground on 12V boost control solenoids from a logic 5V signal. Depends on how VAG cars are wired. Have you considered just using an AVC-R?
ibizacupra
28-09-2006, 18:42
Have you considered just using an AVC-R?
no but I am interested to know more about them.... and their interaction with the vag ecu.
do you have any advise on them john?
cupra_matt
28-09-2006, 19:00
They only read a few signals which are taken from the wiring loom that goes to ECU. RPM signal, Throttle Position, and vehicle speed. It is idependant from ECU.
Mine is still working a treat, no fault codes and made a big difference. Well tested kit that works well
ibizacupra
28-09-2006, 19:34
They only read a few signals which are taken from the wiring loom that goes to ECU. RPM signal, Throttle Position, and vehicle speed. It is idependant from ECU.
Mine is still working a treat, no fault codes and made a big difference. Well tested kit that works well
It sounds very promising.. Its the deviation thing from ecu's expected MAP sensor reading vs its request vs actual.
The ecu's throws a deviation code if it wonders off more than 250mbar I thought & have seen.. dropping into soft limp.
If yours is working ok, then its possible.
Where did you get yours from MAtt? how much dare I ask?
john banks
28-09-2006, 21:07
http://greenline.jp/ is the cheapest I've found.
cupra_matt
28-09-2006, 22:51
Mine isn't actually mine, borrowed from a mate who's car is off the road for the fore seeable future. It came as part of his turbo kit from Japan.
But around £ 250 will buy one.
See here. This is the limited edition Black version
http://cgi.ebay.co.uk/Limited-Edition-Apexi-AVC-R-Boost-Controller-AVCR_W0QQitemZ280030514373QQihZ018QQcategoryZ72205QQrdZ1QQcmdZViewItem
Bill, don't know if this is of any help to you. Been thinking of getting one myself for some time.
http://www.elitedubs.com/text/index.php/topic,741.0.html
http://www.cardomain.com/item/GRE15500209
ibizacupra
04-10-2006, 08:20
thanks for that. looks handy.
I have an Apexi AVC-R on the way to try.
Found my wastegate flapper was partially seized when I stripped it down after last race to check things. Prolly explain some of the weird control issues it had during the race. Fixed it for now as best I can to do next race whilst I discuss it with the supplier (warranty)