[Nezil]

I've ordered an HFS-4 WMI system and I'm waiting for it to arrive. While I wait, I'm preparing for the installation by planning out the control unit location, the 52mm gauge location and things like that.

This is the focus of my other thread, but I wanted to start another thread about creating a more elegant fail-safe solution based on the concept of piggyback tuning.

I like the concept of progressive control and PWM at the valve rather than the pump, which is why I went with Aquamist, but the suggested fail-safe is a bit aggressive, and inelegant.

Currently the suggested connection scheme has a relay in the WMI controller break the connection to the electronic waste-gate position sensor. Obviously this will work, but it will also put the drive-train into 'limp-mode', and create a CEL.

I don't think this is a failing of Aquamist; the control system provides several options for fail-safe, it's just that Aquamist is a WMI controller, not a piggy back tuning device. I'd like to have a fail-safe that reduces the risk of damaging the engine, reduces power, but doesn't cause a limp-mode.

I reached out to Burger Motorsport to see if they would be interested in interfacing with the Aquamist controller and providing fail-safe, but they responded by suggesting I use their WMI system in its entirety instead... not what I was asking for at all.

This however got me thinking... Some of the simplest piggyback tuning products simply intercept the MAP sensor and provide a biased sensor output to the engine management system so that it effectively targets higher boost than it thinks it requested. This approach could be made to work in reverse, to provide a more elegant fail-safe than simply cutting the signal to the waste-gate position sensor cable as is currently suggested for EWG N55.

It would seem to me that it should be possible to bias the MAP sensor voltage higher than actual, effectively telling the management electronics that boost is higher than it really is, causing the waste-gate to lower boost, protecting the engine.

So I'd use the HFS-4 relay output, or the map switch output (orange of the green harness) to activate the biased voltage in the fail-safe condition, and simply bypass the signal in the regular condition.

I'm not an electronic engineer, but before I go about prototyping something like this, can anyone see anything wrong with my suggestion?

[Poochie]

Hi there,

I would like to learn more also, I have a naturally curious mind.

I cracked open a JB Stage 1 & Dinantronics ECU in attempt to reverse engineer them but other than be able to identify some resistors and the main processing chip, I was at a lost. I guess being a Internet Mechanical Engineer can only take you so far as the next Youtube tutorial.

From what I understand and observing how both piggyback operates is a little different; for instance; the JB1 intercepts and manipulate the MAP & TMAP sensor data only and depend on the knock sensor to play catch-up and adjust the other necessary setting (Timing, fuel, ect).

However, the Dinantronics plugs directly into the ECU socket, so it intercepts every sensor and alters the original data to it's own before the ECU has a chance to interpret it. That way it is able control what the ECU see and believes to be current, thus controlling how it reacts, based on set mapping and MO. It can match and compensate for fuel and timing before the knock sensor has a chance to react, thus, a more linear power delivery.

Both are quite ingenious, if you ask me. I'm surprise people don't appreciate and enjoy it more, instead of focusing on the possible warranty ramifications. Like whatever.

[Nezil]

There are a number of ways this could be done, but what I've done so far, is to plan out a simple circuit with Op-amps that achieves the goals - Do nothing if a 5v 'OK' signal is received, and reduce boost progressively (by biasing the MAP sensor voltage high) if this signal drops to 0v.

I'm working with some electronic engineers to validate my design before I build and test it.

[GoneIn4Secs]

Originally Posted by Poochie

Hi there,

I would like to learn more also, I have a naturally curious mind.

I cracked open a JB Stage 1 & Dinantronics ECU in attempt to reverse engineer them but other than be able to identify some resistors and the main processing chip, I was at a lost. I guess being a Internet Mechanical Engineer can only take you so far as the next Youtube tutorial.

From what I understand and observing how both piggyback operates is a little different; for instance; the JB1 intercepts and manipulate the MAP & TMAP sensor data only and depend on the knock sensor to play catch-up and adjust the other necessary setting (Timing, fuel, ect).

However, the Dinantronics plugs directly into the ECU socket, so it intercepts every sensor and alters the original data to it's own before the ECU has a chance to interpret it. That way it is able control what the ECU see and believes to be current, thus controlling how it reacts, based on set mapping and MO. It can match and compensate for fuel and timing before the knock sensor has a chance to react, thus, a more linear power delivery.

Both are quite ingenious, if you ask me. I'm surprise people don't appreciate and enjoy it more, instead of focusing on the possible warranty ramifications. Like whatever.

Interesting, i think most ppl don't know al that

[Nezil]

Originally Posted by GoneIn4Secs

Interesting, i think most ppl don't know al that

What I'm trying to design / build is closer to the inverse of a Dinan Sport Tuner (or similar), which only intercepts the single TMAP sensor input.

I've not studied a Sport Tuner, but my understanding (if you remove the Bluetooth and phone app control etc.) is that it's simply intercepting the Boost signal voltage lower than it really is so that the DME adds boost to reach its desired set point.

The knock sensors on the engine will pull timing and / or boost and / or add fuelling to combat pre-ignition and if there is any headroom available, this approach will make use of it.

A single sensor modification is somewhat crude and inelegant compared to multi-sensor piggybacks and full DME flashing, but it does work, and doesn't seem to cause a CEL. I don't think I'd want to push this approach too far with poor fuel though, and not even Dinan provides a warranty with their Sport Tuner product.

My plan is the opposite - to bias the voltage higher to simulate higher boost and have the DME pull it down, to act as a fail safe without CEL.

One of the really nice things about the TMAP sensor is that it is supplied with 5v to operate; you don't need external power for any piggyback for that sensor.

[Nezil]

So here is the ISTA+ details of the TMAP Sensor output. I'm sure it's not absolutely perfectly linear like is shown here, but that's the design intent:

The output is absolute pressure rather than purely boost, with Atmospheric pressure at sea level being 1013.25 hPa, or ~2.0v on our 2.5bar sensor. Anything less than 2.0v is vacuum, and shouldn't be altered. Anything above is boost, and can be.

Here is the pinout of the TMAP, also from ISTA+:

[Nezil]

Done... Details in this thread: https://f87.bimmerpost.com/forums/sh....php?t=1622247