Havepitty in W.Van

recently got greddy profec b,

here is the beef,

N75+MAP (stock)
when our cars are going uphill You are PART Throttle with boost reading ~5psi AFTER TB.
our MAP senses how much boost there is BEFORE TB and regulates CMD boost.


EBC+clamped MAP
now with EBC, in the manual i got with it wants to READ BOOST after TB or FPR lines.
so now, if you were going uphill - PART Throttle and reading ~5psi AFTER TB, the pressure BEFORE TB will not be read properly by MAP. EBC still thinks its only doing 5psi and wants wastegate closed till 20psi.
so we could have 20psi BEFORE TB, while only reading 5psi AFTER TB.

do you guys think its better to hook up EBC BEFORE TB?

Audi2ptzero

it just makes sure that what it is reading is close to what you should be making at the time.


The EBC and the N75 valve both get hooked up to the turbo compressor housing.

Also that 5psi your reading on the EBC is just telling you what boost pressure your running at that time. It just reads it out the same way a gauge does which gives you a vacuum reading too. If you put it before the TB it will never read vacuum on the EBC.


BTW the instructions should tell you to install the 3rd line into the BPV line not the FPR line.

Audi2ptzero

which IIRC has the vac line going into the back of the unit inside the car, it should just read out the vac/psi like a gauge and does not use it in anyway to contol what the unit does to the wastegate. That is done with the step motor that you install under the hood.


Funny things is I was also just playing around with my HKS EVC IV tonight, since it was only producing 10-12psi max. So I reset it and ran it thru its learning mode. Now it is hitting 20-25psi with the huge turbo. Just need to turn up the boost setting with the GIAC Mobile Tuner and everything should fall into place. =)

Today was a good day, all except that pain in my jaw from having oral surgery on thursday.

Havepitty in W.Van

Stock car
N75 valve controlled by MAP which is located BEFORE TB.


EBC car (Solenoid replaces N75 completly, MAP is clamped)
Solenoid valve controlled by EBC. EBC reads boost AFTER TB.


the boost BEFORE and AFTER TB can be different because of the TB partially open.

so if i am reading 5psi or x psi AFTER TB, BEFORE TB could be more than that value.

since the EBC is reading AFTER TB, it would keep demanding more boost while BEFORE TB you may have exceeded the maximum boost setting.


as an example,
you are going uphill, and you are partial throttle and reading 5psi (car is under heavy load) on your boost gauge which is AFTER TB.

now with the new EBC, it would also read 5psi, and would demand more boost. this could increase BEFORE TB boost over maximum specified because EBC is only seeing after TB.

so if EBC were to see boost BEFORE TB, once turbo has created maximum set boost, it would stop getting any more boost - which is exactly what a MBC does.

so i am questioning if its better to have the EBC reading boost BEFORE TB instead of AFTER TB.

Audi2ptzero

is what the EBC is using to see how much boost there actually is. The vac line that goes from the intake manifold to the step motor or to your main unit like the Profec B, just acts like a boost gauge so you dont have to have a actual boost gauge with the profec b.

So by putting your small vac line before the TB your just going to see no vacuum and a much higher reading on the screen.


A MBC works in a way that just opens a valve to only allow so much pressure to the wastegate or just leaks off pressure the whole time so that the wastegate thinks it is getting less pressure to open it.

Havepitty in W.Van

i didn't know solenoid had a built in pressure detector.

i always thought the solenoid was just an electronic valve.

so if what you say is correct, then i don't even have to hook up the EBC to vac/boost line... since it is only using it as a boost gauge.