Quote:
Originally Posted by shadow191
I thought the N54 DPFix already modified the O2 signals. It doesn't just send it's own as some early model O2 sims for other cars did. The DPFix being sold is pretty much a variable resistor so it takes the inputs and tweaks the output voltage to keep it in spec with what the DME expects. That seems to be exactly what you're proposing and it doesn't work on the N55.
|
That's news to me. However, a variable resistor is much different that what this is doing.
A variable resistor (if that's what it really is) is probaly used just to implement a voltage divider. You can't really do much else with just a resistor. Maybe there was some RC filtering cirucit to "smooth" the edges, but those are all "passive" modifications.
This unit actually has a microcontroller which samples the input signal, applies a mathemical model to it, and reproduces it on an output.
Basically, it seems like this guy modeled a catalytic converter in the form of a transfer function or something.
EDIT: If it turns out that the BMS DP Fix is actually a similar design, then yes, this might not work. However, there's no physical reason why the o2 can't be successfully simulated with enough effort to model the system.
EDIT 2: So I did a little digging. It looks like the BMS DP fix is in fact just a variable resistor and a diode. I'm actually surprised that such a setup worked on a car as new as an N54 car. This setup doesn't have the ability to change the frequency of the signal, just the amplitude and distortion (due to the diode). As far as I know, frequency is one way that the ECU measures cat efficiency. If the AFR is changing too rapidly, it's a sign that the cat may be bad (or not there).