LC-1

[Extinct]

Thanks, I figured it out today talking to a bud of mine. The H02 low wire on the NB is actually connected to the body of the NB, so that it is in effect grounded to the exhaust pipe. Confirmed with my DVM. So now I know all I need to do is ground the NB low and the LM1 Analog ground and I will be golden !

Thanks for the response !

[jsttry]

what is the voltage on the high and low NB meant to be?

[ringram]

unconnected they come out 5v and 4.5v or there abouts.

[Extinct]

Not exactly correct, the NB high voltage varies from 0 to 1.1 volts, that voltage is actually created by the 02 sensor. NB low is just a reference ground, ground it to the chassis and you will be good to go. The PCM does send a reference voltage out down that wire, but it does so just to establish the reference ground point. Disconnected you will measure .45 volts at the NB low

[ringram]

Sorry yeah I was talking of the PCM NB02 wires not the LC-1 ones.

[joecar]

The PCM preloads HO2S Low with 4.0V and HO2S High with 4.5V (each wrt to PCM ground);
the NBO2 sensor then rides (adds) its +/- 0.5V on top of HO2S High;

So (with NBO2 sensor plugged in)...
a. wrt to HO2S Low, HO2S High ranges from 0.0V to 1.0V.
b. wrt to PCM ground, HO2S High ranges from 4.0V to 5.0V.

When connecting a WBO2 to simulate NBO2, keep in mind that PCM Ground and HO2S Low are not at the same (i.e. WBO2 analog ground should not be connected to any other grounds; if it is connected to vehicle ground, say, then this will try to pull down the PCM's HO2S Low from 4.0V to 0.0V (...and may wreck the PCM...?)).

[Extinct]

I don't think grounding the H02 low to chassis ground will fry the pcm, because when I checked the NB sensor I removed from my system, the low wire was connected directly to the body of the sensor, no resistance at all. That tells me that the low wire is grounded and the pcm is just looking at it to determine the ground reference value.

[ringram]

Yeah check out this from the man himself Klaus at Innovate

--
Hi,

The reason the LC-1 has multiple grounds is precisely because the heater current is large and can create ground offsets. By connecting it to a different ground point you avoid that. Connecting the dataloggers ground reference to the system/analog out ground point should eliminate any ground offsets. To test the datalogger's reference itself, connect it's input to the system/analog ground point instead if the analog out. What you'll see is the dataloggers internal ground offset if any.

Regards,
Klaus
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Also see the rest of the thread here http://www.innovatemotorsports.com/f...ead.php?t=2489

This is why I tied all my LC-1 grounds together. Unless I misunderstood something?

[Extinct]

Exactly ! Later in that same thread Klaus discusses why most pcm's use the engine as there reference ground. This is what I found when measuring the H02 low signal wire, it gets grounded to the engine via the exhaust system.

My bud grounded the LM1 ground, the datalogger ground (not flashscan - LT1, and the H02 low (ground) all to the same spot on his engine.

I can't test this on my car right now because it is in the body shop, but a week from tomorrow I should get it back and will test it then and report back here.