HFS-6: Setting up the fail-safe?
 

HFS-6 osa User Manual v4w

Page 6; right column, 3rd paragraph:

8-feet of two-core cable from the FCM is intended
for fail-safe purposes. It activates a low-power 3-
way solenoid valve to by-bass boost pressure to the
wastegate. In the event of a fail-safe activation,
it will lower the boost down to the mechanical fail-
safe setting. This option is normally intended for
use with a manual boost controller and some step
per-motor based electronics boost controller.

My question is, what if you are not running a MBC or a EBC? Boost is controlled through the DME in the BMW N54 engines. How would i go about hooking up a fail-safe?

Thanks in advance.

Tee

If the wastergate is bypassed to the turbo outlet, no electronic controller can override it, It has to drop down to wastegate pressure.

What is a DME?

LOL, sorry. It's BMWs ECU...

You spice the boost cut wires directly to the stock BCS wiring at the ECU. Usually it's a two port solenoid, and when the signal is interrupted the solenoid will bypass boost pressure directly to the wastegate(s).

Just to confirm Jamal's post, the section on the page 18 of the user manual refers to this connection (Example 1&2).

Yellow harness: Cut the BCV contoller wire from the ECU to the BCV.
- white wire to ECU side
- brown wire to the BCV side

To aviod CEL, enable the "DR-ON" link as instructed.

Expanding on this, I'm running a MBC, so how would I have to do it to get the benefits of wastegate boost failsafe.

If you are running a MBC, the only option is the MAC valve (page 19). The MAC valve bypasses the MBC during failsafe activation and drop the boost down to wastegate.

Other failsafe option offered by the HFS-6 will not work with MBC because of the mechanical nature of the MBC.

So then all it will be doing is reading voltage? And what boost cut wires? See the problem we may have there is that we are already tricking the ECU to think it is running Lower boost levels then it actually is so that CELs are not thrown.

The ECU controls boost via a solenoid valve (BCV) by PWM'ing it. I assume your ECU (DME) does the same.

The HFS-6 can cut this connection between the ECU and the BCV upon failsafe activation.. This is done via the yellow harness:

Cut and splice as following:
- White ........... ECU side
- Browen ......... BCV side
To avioid CEL (check engine lamp), read the second half of page 18. Referring to the Dummy resisrtor.

I just went out and bought an EVO X to add to my collection, so i'm just going to install the HFS-6 in that instead along with the GT35r Turbo Kit :)

Any pointers you wanna give me for the EVO X install???