Brettus

iTrader: (2)

OK , after two years , I finally convinced someone to do this modification.

He was having a hard time with throttle control at partial throttle (to the point of it being dangerous) . Changed the line to the Electronic Boost Controller from the UIM to just before throttle plate and .................................................. .................................................. ..........................it worked !

RotaryMachineRx

iTrader: (1)

Don't most people plumb it to the turbo outlet; which is pre TB anyways?

Brettus

iTrader: (2)

You are talking about the line to the boost control solenoid .

I am talking about the line to the Electronic Boost Controller itself .

RotaryMachineRx

iTrader: (1)

Oh, isn't that just for the electronic boost gauge though? My understanding was this it had nothing to do with wastegate control? Or does it work along side the solenoid signal....

Brettus

iTrader: (2)

Yes it is for the boost gauge , but it also determines "start boost" and "warning" . These are the signals the BC needs to do its thing with the solenoid .

Hook the line into the UIM and at partial throttle the BC does not see a signal and stays off . The WG actuator has no air to it so the WG stays closed .

So the turbo is free to spool up to wherever it wants to in this scenario. So imagine you are half way around a corner modulating the throttle then you suddenly get a huge unintentional rush of power to the wheels - not nice.


The person I mentioned above almost crashed a couple of days ago as a result of this happening . Hoping he will come on here and recount his experience.

MazdaManiac

iTrader: (3)

Properly sized turbos fix that.

If the boost target for a small turbo is kept where it is supposed to be, you won't get a giant "surge" of pre-throttle overboost.

This is a band aid to cover over-spinning a turbo past it's system design Pr.

Brettus

iTrader: (2)

Not having had any experience with a larger turbo - I have to accept that .

However - the vast majority of turboed 8s are Greddys and they WILL get this surge whether it's set to run past its system design or not .
Perhaps if the "start boost" setting was set to zero you would eliminate the issue to some extent but kind of detracts from one of the major benefits of having a BC in the first place .... fast spool.

So more of a Fix than a band aid .....

MazdaManiac

iTrader: (3)

No - with a properly set-up boost controller demanding only the rated amount of flow from the turbo, there will not be surging.

Brettus

iTrader: (2)

No . It does not matter what flow the BC is set to achieve.If there is no signal from it to open up the WG the potential is still there for a surge.

And there wont be a signal until the UIM reaches the "start boost" point if set up the way you suggest.

AT part throttle , 0 psi in the UIM is actually pretty damn quick and the turbo is spooling very nicely - have you not noticed this MM ?

Brettus

iTrader: (2)

Bump.

Was looking for some info in here and started reading it again . Still amazes me how certain people did'nt get this .

Info is still relevant today .

Don't plumb your EBC into the UIM !!!!

wcs

iTrader: (2)

Thanks Brett

HexRX

After reading all of this shitstorm I am still a bit confused.

Wouldn't the boost sensor for the Electronic Boost gauge (not controller) be placed right after the TB to detect the current air pressure going to the combustion chamber. Yet You would Plug the controller selonoid right before the TB?

9krpmrx8

iTrader: (46)

No.

Brettus

iTrader: (2)

Put the line going to the EBC before the throttle body and the one going to the solenoid just after the turbo.

But the gauge (not the EBC gauge) should be after the throttle body .

HexRX

I was referencing the AEM Tru-Boost Boost Controller/Gauge.
So I was right with placing the gauge that will read off the current boost pressure, after the TB.
The solenoid for the EBC will be routed right after the turbo into the piping that will lead to the Intercooler and the other line right before the TB..

If this is the current routing, then I agree with your point of view Brettus.

Brettus

iTrader: (2)

This is where the confusion comes in ................... The AEM boost controller/gauge needs to be BEFORE the TB.
Any other boost guage (not related to a boost controller) should be AFTER the TB.


To expand on this .... the AEM boost controller/gauge is displaying boost , but it is also controlling boost .
If it is Placed AFTER the TB it loses control of what the turbo is doing when the throttle is partially closed. Which is why if you set it up this way your throttle control at part throttle (for smaller turbos in particular), goes to hell in a handbasket .

JimmyBlack

I'm not fully convinced by either argument about whether EBC controller signal source should be pre- or post-TB. Running pre-TB worked nicely for Brettus, though it is not a common best practise, and differs from several EBC installation manuals.

I tested both signal source locations earlier this week. My setup is detailed in my build thread here (there's a useful diagram in there that details vac hose routing).

Instructions for my GFB G-Force2 EBC state that EBC signal feed should come from the manifold where a vacuum source can be seen. I.e. not pre-TB as per Brettus' method.

So what happened when I hooked up the EBC signal source pre-TB? My EBC would not let me configure it, as it only allows configuration while the EBC signal sees vacuum, and at no time does the pre-TB location see vacuum. It is essential to be able to configure the EBC in whatever location you choose to source the signal from. Since I can't do this pre-TB with my brand of EBC, I've moved back to running the signal source from the manifold as per common best practise and the GFB installation manual.

In summary, there's no recorded evidence that indicates Brettus' method is bad, but depending on your EBC you may not have the option to run this method. So don't argue against it, try it and present the evidence here.

If I wanted to better manage my partial throttle predictability I'd be looking at reducing the Gain setting on the EBC, and possibly look at a BOV that operates effectively in the boost range I'm working with.

Brettus

iTrader: (2)

It's definitely a case of whatever works in your particular scenario .
I have mine post TB on my current turbo and its fine . On my old 57trim Greddy setup , it was dangerous that way . Halfway through a corner at say 5000rpm going from part throttle to full throttle ...instant loss of traction and spin out .
This is why the arguments earlier in the thread as for many people with slower spooling turbos throttle control was never an issue to start with.

JimmyBlack

Recently I changed my exhaust to a more free-flowing setup (decat and custom catback). At this point the partial throttle issue with unpredictable throttle response and surging immediately became a significant issue when running any Gain on the EBC. I'm talking 1-5psi UIM while 30+psi pre-TB, surging back through my anti-surge compressor housing.

After a lot of Internet searching it appears that this issue is typically reported by people running smaller faster spooling turbos, and I couldn't find a single sensible solution to this issue.

I got hold of the good guys at GFB to get the low down. Here's what I got from one of their engineers. UIM is the normal signal source for EBCs. If however you're seeing surge or unpredictable throttle response partial throttle, try the following:

It is acceptable to hook up the EBC signal pre-TB, and the GFB unit "should" be configurable from here, though the car should be at idle to minimise pre-TB boost reading, and may need to be re-calibrated/zero'd - search youtube for "calibrate GFB". +1 for Brett, you have the support of a manufacturer.

Another cool alternative is possible if you have a "Scramble" feature on the EBC. When you're running your standard preset values, you press the Scramble button and it shifts to your Scramble preset values for several seconds. Useful for overtaking, etc. On the GFB you can hook up an external switch that activates Scramble mode. Hooking up a microswitch under the accelerator pedal so that it activates Scramble at WOT is the business. In this scenario you'd run with 0 Gain on standard preset and when you go WOT, Scramble mode with a high Gain configured would kick in. Perfect, since the Gain setting only causes issues at partial throttle.

Brettus

iTrader: (2)

BUMP.
As my turbo is now spooling quickly again I changed my setup back to pre throttle body. Made a huge difference in throttle control . Much better .
Example situation ... accelerating slowly out of a sweeper . With signal post throttle it was either (pretty much) all or nothing . With signal pre throttle ...perfectly controllable .
Anyone with a fast spooling turbo really should do this .

yurcivicsux

mine was originally pre- throttle and we had lag issues, now with the BNR turbo it is where it should be right at the turbo. with all things not being equal on my build i'm not sure if we would have left it there; it would have been an issue or not. i needed that spot right before my throttle to plumb my meth spray into anyway.

my waste-gate wasn't holding well either so that was certainly 1/2 the battle. i'm running a simply MAC solenoid off my ecu and a turbosmart gauge. everything works very well so far.

Brettus

iTrader: (2)

fixed

yurcivicsux

^^ya agree... if not the whole story. i had it right after the throttle because i was lazy and didnn't want to take that turbo out again (3rd) time as i had so many clearance issues with the gate (don't ask...) . in theory it should work either spot as long as it is before the throttle in the charge piping.

i would even argue that pre throttle and not directly at the turbo is best, (although i know this is incorrect) i don't understand why.... response time?

Brettus

iTrader: (2)

Hardly any difference at all between those two spots. Like you said , anywhere in the charge pipe pre throttle works well .
It does make a difference for the line to the solenoid though . You can get a little more top end boost (less than 1psi) by putting that line just before the throttle vs straight off the turbo .