[RayLivingston]

I'm actually having a problem with my E46, but getting no useful information from the E46 forums, so thought I'd try here. I've been in a similar position with my E90 335i in the past, and I figure the engine controls on the two almost certainly operate on similar principles.

I'm very confused about how to interpret O2 sensor readings using various software. I get very different results, depending on which software I use. For example, at the moment, OBDFusion gives me one set of readings, INPA another, and TestO yet another. I tend to trust TestO most, because it allows me to see the actual waveform, rather than just periodic sensor readings as I had assumed. It appears to me both INPA and OBDFusion are NOT simply giving periodic samples, but rather giving some filtered/averaged/interpreted readings. So, while INPA may show a more-or-less constant value, or a series of readings covering some range of voltages, TestO shows me the actual, rapidly changing voltage readings, which generally span a considerably wider range than what I see with the other tools.

So, I'm not sure how to interpret the readings in OBDFusion and INPA. When I often see a more or less constant reading on those tools, I expect the DME to be upset, yet it often isn't. I expect to see readings varying from ~0.1V, to 0.9V, but they often don't get even close to that, even when the sensor voltage actually is switching over that range. Other times, I see the readings varying in what seems a reasonable manner, but then the DME throws a "no activity" code on one or the other sensor, then pumps the short-term trims to wide-open (+27.5%).

Now, yesterday, I cleared all faults, and, after a couple of hours driving doing errands around town, the ONLY fault logged was an O2 Heater fault on Bank1 pre-cat! Both the O2 sensor and O2 Heater monitor tests had passed, it was perfectly happy with Bank2! I swap in a different Bank1 sensor, and the first fault it throws is a Bank2 "no activity" fault, even though I can SEE the bank2 sensor toggling full range at 1-2X per second. It's like the DME is seeing something completely different from what the tools are showing me.

Just for grins, I disconnected BOTH pre-cat sensors. So far, the only faults I have are two pending O2 heater faults. The engine runs great, short-term trims stuck a 0.0%. Why am I NOT getting the "no activity" faults?

This is driving me NUTS, and I'm about to push the thing off a cliff!

[pheno]

The thing is that "refresh rate" in TestO is far beyond INPA and that's why you're able to see real waveform in TestO. INPA polls values not so often.

[gbalthrop]

I don't know anything about TestO, but as Pheno suggests, ANY Scan Tool or Diagnostic Software (INPA/ISTA) I have used has a "Refresh Rate" of anywhere from < 0.1 second to ~ 2 seconds. The Refresh Rate can be MUCH faster if you limit the number of Parameters (signals read) to just ONE, instead of having 10 or more Parameters displayed.

I don't think INPA is "averaging" anything, but rather it is simply showing whatever value was currently being received by the DME at the instant that parameter value was being read. The MORE Parameters or values there are to read and display on a particular screen, the LONGER between reading of a particular value (LONGER the "Refresh Period" or Slower the "Refresh Rate").

If you use ISTA, you can easily see the difference in something as simple as a digital switch (On/Off) indicator, in how fast the On/Off designation changes when you press a button/ Switch with ONLY ONE parameter selected, vs with ALL available parameters selected.

With INPA, there "appears" to be a way you can "Select"/ Auswahl/ F8 only one or two parameters from the dozen or so that appear in the standard screens. I have NEVER used that function. If you are ONLY displaying ONE Parameter, you will get the fastest possible Refresh Rate for that software (AFAIK ;-).

ANYONE who HAS used the F8/ Auswahl/ Selection feature to display only ONE or two Parameters, such as O2 Sensor Voltage, please explain PRECISELY HOW that is done. Folks like me need to be educated.

George