Bad BCS symptoms?

gijonas · Post by **gijonas** » Thu Jul 23, 2009 12:30 am

Just trying to pin down why i can not get more than 7-8 PSI out of my car.I have the Revtronix stage 2 with all needed mods blah blah whatnot.Anywho i wanted to rule out boost leaks(which i already knew wasnt the prob) and a couple other things by going for a quick and careful drive with the wastegate disconnected.OH YEAH!! thats what i wanted to feel LOL.

So i pulled back into the shop and put compressed air to the inlet to my BCS with the outlet open to air.In doing this i find that the BCS is not restricting airflow whatsoever,this is with the ignition on or off,is this right?? The BCS should be closed untill told to open right?

Anyways i think this is the problem since the boost i am seeing is the same as the pressure in which my wastegate seems to start opening,however i can sometimes see as much as 11 PSI with a long 4th gear uphill pull...I think now that this is just creep?

What do you all think.anyone got a good BCS test? If this turns out to be the problem are these still available new?

EDIT: Just took it off and put battery voltage to it,seems to click nicely with power to it.Also just checked my routing as compared to vikash's diagram all seems well there as well.

gijonas · Post by **gijonas** » Thu Jul 23, 2009 5:37 pm

Anyone?

Post by **Legacy777** » Thu Jul 23, 2009 7:42 pm

The BCS is normally open. With no voltage applied to it, boost from the compressor will go right through it to the wastegate.

With voltage applied it will close off.

I would try and use Vikash's scan tool or some other form of logging to see what the BCS duty % is when you are trying to make boost i.e. floored throttle. The duty % should be above 70%.

gijonas · Post by **gijonas** » Thu Jul 23, 2009 9:23 pm

Hmm i was afraid of that LOL.Nothing is easy.I suppose this is something that wont throw a code if it isnt working right? Seems to me that if what you say is the case then i am never getting voltage to the solenoid for whatever reason.

Post by **Legacy777** » Fri Jul 24, 2009 6:52 pm

There should be 12v at one lead of the BCS with the ignition in the "ON" position. You can test that without even starting the car.

The other lead goes to the ECU and "sinks" the current, switching it on & off, giving you the PWM or duty cycle.

So check that you have 12v at the BCS. There are wiring diagrams and what not in the FSM on my server that you can use (info is in the stuff you need to know forum)

gijonas · Post by **gijonas** » Fri Jul 24, 2009 8:52 pm

Thanks again.No spoonfeeding wanted...yet

gijonas · Post by **gijonas** » Sat Jul 25, 2009 4:32 am

Ok so i did some checking.I DO have 12v to the yellow wire with ignition on - ok.Now i also have continuity between the other wire and the connector to the ecu.Also i have the specified resistance between the two terminals of the BCS itself.On top of this i have also confirmed that the unit seals fine when power is put to it.Sooo WTF?

I may be missing something but it seems quite clear to me that this has to be the problem in some way givin my issues.So far it seems that there is no control via the ecu for the solenoid,am i concluding somewhat accurately? Not really sure what to try now and im not really in a position to equip myself with a scantool right now.

gijonas · Post by **gijonas** » Sat Jul 25, 2009 5:01 pm

This got old pretty fast,anyone recomend a good EBC lol.

gijonas · Post by **gijonas** » Sun Jul 26, 2009 6:11 pm

Just wondering if anyone might know what role the MAP or pressure exchange solenoid might play in all this.Also just for reference: if i did do some logging and found the BCS duty cycle out of range,where would that put me?and if it were within range,where would that put me?.I am simply willing to rule stuff out by trial and error right now as i have no access to a laptop right now.

Post by **Legacy777** » Mon Jul 27, 2009 6:49 pm

You have to remember the BCS is an output from other inputs, MAP sensor, engine load, etc.

So if you have a bad input to the ECU that could cause the output to the BCS to messed up.

Are there any other symptoms you are experiencing?

gijonas · Post by **gijonas** » Wed Jul 29, 2009 5:22 pm

Well, i have gone through and refreshed,adjusted,and replaced so many things that this really is my last remaining problem.The car really is smooth now with the 2nd version of the revtronix chip aside from a couple small annoyances.

The only other issue i can think of that is related is a weird low RPM - high load kind of surging while accelerating?Not a skip or hiccup but just a surge,kind of like gently pulling up and down on the e-brake while trying to accelerate.That is all that i can think of.I am wondering now if maybe i should source a new MAP sensor and exchange solenoid to see if either of those are a problem? In reality those two things and the ecu are all i have not changed.

Also want to add that i have 10x checked all vacuum hoses and boost lines ect.And some good news - i took the plunge and have a laptop coming soon so i can log at least.

Post by **Legacy777** » Wed Jul 29, 2009 7:34 pm

Have you checked/tested your BPV?

gijonas · Post by **gijonas** » Wed Jul 29, 2009 7:48 pm

I actually have a new Greddy BOV.Works excellent as far as i can tell,and yes it vents to atmosphere but i didnt see this being the problem.In fact i dont even see the temporary rich moment happening on my LC-1 when shifting,though im sure it is there.

SLODRIVE · Post by **SLODRIVE** » Wed Jul 29, 2009 9:10 pm

No offense, but I gotta ask this since it hasn't been posted yet: Are you SURE the vacuum hoses are hooked up correctly on the BCS?

gijonas · Post by **gijonas** » Wed Jul 29, 2009 10:16 pm

No problem.Yes i thought for sure one day that that would be the problem,nope - got it right the first time.

asc_up · Post by **asc_up** » Wed Jul 29, 2009 10:19 pm

You don't by chance have a fuel cut defender, do you?

gijonas · Post by **gijonas** » Wed Jul 29, 2009 10:21 pm

Nope no FCD.Just the chip.This really bugs me.

asc_up · Post by **asc_up** » Wed Jul 29, 2009 10:28 pm

Darn. Actually I just realized that a FCD would actually cause you to over-boost anyways.

Have you tried hooking up a MBC, just to see if that is indeed the problem? Maybe your turbo or wastegate is bad. Just throwing out scenarios at this point haha.

gijonas · Post by **gijonas** » Wed Jul 29, 2009 10:33 pm

As i stated in the first post its not the turbo,cuz i drove around with the wastegate disconnected and it was awesome lol.And as far as i can see from my testing,the wastegate starts to open at about 7-9 PSI.And yes there is a valve cup connected to the wastegate arm.

asc_up · Post by **asc_up** » Wed Jul 29, 2009 10:37 pm

Oh woops. Missed that

Do you by chance have access to another turbo Leggy? That way you could easily swap the entire bracket that the BCS, MAP sensor and pressure exchange solenoid are all on to see if it works.

gijonas · Post by **gijonas** » Thu Jul 30, 2009 1:57 am

I wish i had another.

My plan at this time is basically this.....to hell with this shit already.I am going to buy an MBC although i am not a big fan of the idea.In the meantime i am going to get setup with Vikash's scan tool as well as evoscan (for fun) and see what i can figure out.Worst case scenario is i wont be able to figure it out A. and B. i will also not like the MBC and end up buying an EBC.What the hell,its just all my money and time

Post by **Legacy777** » Thu Jul 30, 2009 6:41 pm

You sure you BOV isn't causing you any issues?

Regarding the MBC. I've got my Joe-P MBC still for sale. It's an excellent MBC, and I've fabbed up a bracket so it will mount to the stock plate. If you're interested, make me an offer.

http://bbs.legacycentral.org/viewtopic. ... t=joe++mbc

gijonas · Post by **gijonas** » Thu Jul 30, 2009 8:36 pm

Well like i said it seems obvious to me that the problem lies in the boost control because i get fast clean boost and as much of it as i want after disconnecting the vacuum line to the wastegate.So it would seem that if my problem were to be somewhere else then the problem would still persist despite my wastegate override test....right?

EDIT: if you had offered me the MBC like 10 minutes sooner i would have bought it.Just paid for one of those cute perrin ones.

Post by **Legacy777** » Thu Jul 30, 2009 10:53 pm

D'OH!

Return it and buy mine

It's better and will add eleventy billion hp.

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Bad BCS symptoms?

Bad BCS symptoms?