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VR457
02-04-2011, 12:31 AM
From various posts on here and Ozvr4 it seems there is little consensus on whether to disconnect the factory boost controller when fitting an aftermarket manual / electronic boost controller.

Has anyone tried both options, keeping it plumbed in / closing off the pipe to it?

Alternatively, does anyone have a dyno boost graph to show potential differences with it disconnected / not?

BEG4ME
02-04-2011, 02:25 AM
I had a manual boost tap on mine to raise the boost. Was put in between the hard pipe and solenoid and it raised the boost fine. Was really touchy but they may have been the tap. No graphs though sorry but it did go better.

Kenneth
02-04-2011, 02:36 AM
You can leave it electrically connected and use the standard piping to plumb in your MBC/EBC.

There is no real good reason to leave it plumbed in though as you still have to work around the standard boost control and as a result get a very similar looking boost graph, just at a different level.

BEG4ME
02-04-2011, 02:42 AM
I did put my tap in like that before learning about the standard solenoid. I just thought it T'ed off to each turbo from the hard pipe.

Davezj
02-04-2011, 10:24 AM
Yes the standard factory boost solenoid is inline between the hard pipe and the T that goes to the 2 wastegates.

Most people fit the manual/electronic after market boost solenoid in exactly the same place as the factory one. just remove the pipes from the factory one and fit to the after market one. But leave the factory electrical connector on the now disconnected factory boost solenoid. so the ecu does not get confused and think there is a problem woth a faulty solenoid.

I am not sure if it is strictly necessary to leave the electrical connection to the factory solenoid But it will not harm/confuse anything if you do.

VR457
02-04-2011, 08:13 PM
So what happens if you leave the hose on the factory boost controller as well as the MBC? I've had it like that for ages but wondering if i took it off and just ran boost from the MBC if anything would happen.

Davezj
02-04-2011, 11:14 PM
to be honest i don't think you will notice any difference if the stock solenoid is left inline.
i can't say this for fact it is just logical reasoning.
as long as the MBC/EBC is set to request a higher boost value than stock value i don't think the factory solenoid will have any effect.
as i understand it the factroy setup works as follows:-
1. standard wastegates open at a pressure of 5 psi let say.
2. required normal boost 7psi.
3. as the boost rises to 5psi, if the boost solenoid was not inline then the wastegate would open and as the reves increase and the pressure builds the wastegate open more and more to maintan the 5psi pressure.
4. but with the inline solenoid in place,the pressure rises to the 5 psi point that the wastegate would normally open at , the factory boost solenoid starts to bleed off boost presure, so on the boost side of the factory solenoid you have 5psi and climbing and on the wastegate side of the boost solenoid you have 5 psi.
5. the boost side of the solenoid rises to 6psi and then 7 psi, which is the pressure the engine see's the factory solenoid bleeds off the extra pessure and stilll shows the wastegats 5 psi.
6. if anything abnormal happens (exesive knock or high AFR's) the factory solenoid opens completely and the wastegates see's the full boost presure and limits the boost produced.

so if the MBCor EBC says i want 9psi the after matet solenoid only shows the wastegate and factory solenoide 5psi while keeping the engine boost at 9ps. the factory solenoid does not know that engine is see's 9psi.
so if it is conected or not it will not make a difference if the after market controller is set to more than stock presure. but the after market boost control is set to less than factory levels for any reason it will limit the boost.

i am not really sure why i started to write this post but it seems that i am considerably more drunk than when i started it.

i hope something about this post makes sense, if not then please get a mod to delete this post post.

Kenneth
03-04-2011, 03:18 AM
The ECU does perform boost correction. That means that initially the boost target is good, the ECU does nothing. As a result your peak boost (around 3000RPM or so) is a combination of MBC + OE MBC.
To avoid fuel cut, you will need your MBC dialed in so that this combination does not exceed the fuel cut load limit.

Once you get higher in the RPM range and have been boosting for a bit longer, the ECU correction starts to modify the OE EBC duty cycle to get boost under control. At that point, it brings boost back to less than what you would have had if the OE EBC was not connected.

A rather simplified description, but I believe it to be approximately what happens when you use a MBC in series to the OE EBC. This also reflects the behaviour I have noted from dyno boost graphs given the different configurations.

VR457
11-04-2011, 09:26 PM
Bit late but thanks Dave for the reasoned answer. I think from what Kenneth is saying, if you have both connected then the ECU corrects more higher up the boost range?

Here is my graph from both connected. I'm wondering if the boost dropoff says something?

43688

Kenneth
12-04-2011, 03:11 AM
Other than it appears you are getting boost very early for 3rd gear, that boost curve looks normal for MBC controlled boost.

If you take a look at mine here: http://www.clubvr4.com/forum/showthread.php?30229-Dyno-Graph&p=316159&viewfull=1#post316159
You will see the first is shaped similar to yours and is MBC controlled.
The second (on the right) is standard boost control.

Boost dropping is normal and is probably a number of things, one of those being related to your boost controller. You could try removing the OE boost solenoid and see if you retain boost longer.

apeman69
12-04-2011, 05:26 AM
With an aftermarket EBC do whatever the manufacturer recommends. I found with a MBC that boost spiking seemed less when the factory solenoid was bypassed. ECU trying to get boost in check would explain this.

Sent from my Huge Brain using MyFingers :)

VR457
12-04-2011, 09:58 PM
It seems like it's worth a try then. So, will plumb the solenoid back in on itself whilst replacing the T section with a straight piece. I have an in car boost gauge so can get a rough idea if it works.

VR457
16-04-2011, 01:07 PM
I have been having a look at the piping and realise i have no idea how to bypass the factory solenoid.

The MBC goes down to a T piece which splits, one to the solenoid, the other i presume down to the wastegate. Where do i go from there?

VR457
18-04-2011, 08:50 PM
I have done it! Could not take the extra bit off so blocked it with a tight bolt and cable ties.

Performance wise, the boost seems not to spike as quick but car picks up speed quick enough. It also does seem smoother.

However, all that could just be placebo. If i get round to dyno-ing the car again then that could show differences, if any.

Mr.Salas
23-04-2011, 07:10 AM
Sorry guys to ask this, but how does the boost controller solenoid work? meaning does it get a constant voltage or is it a PWM signal that controls it>?