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boost control solenoid-tech info req'd

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
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glos.uk

Addo

Guest
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

Audi Technician
Dec 15, 2004
1,362
0
Carlisle
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

Full Member
Feb 16, 2002
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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

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
nice info John.
you experienced any issues from a 3 port boost control valve and higher boost levels? (>2bar)
 

john banks

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Feb 16, 2002
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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.
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
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:
 

h100vw

Guest
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

Full Member
Feb 16, 2002
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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?
 

cupra_matt

Audi Technician
Dec 15, 2004
1,362
0
Carlisle
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

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
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?
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
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)