LM1 issue

[Extinct]

Well, I was out yesterday working on tuning, my first time. I did lots of things wrong, but some of you guys helped me understand that last night, thanks to Humpin SS, Tordne, and Black02SS.

However, this morning I have a different question. I was looking at my 02 sensor voltages, because I suspected I had an issue with the way my LM1 was working.

I cannot check it right now because I am at work, however I believe I have it set up so that channel 1 is the NB simulation and ch2 is the wb output. However I may have that reversed, because looking at the display on the LM1 it comes closest to matching the reported AFR of ch1.

Anyway, I will check that when I get home. However, what looks funny to me is the reported voltage. If you look at the attached photo and log file, you can see that I recorded both AD1 and AD2, as well at the PCM reported H02S11 and H02S21. I would have expected the PCM reported voltages of at least one bank to have matched the reported voltages of at at least one AD channel (btw, I have the purple narrowband wire connected to AD1, WB is in pass side manifold), however you can see that none of them match at all !

Any help you guys can give to solving this mystery would be appreciated. I know it is probably a dumb mistake on my part, but I haven't had time to figure it out yet.

I tried to attach the log file, but it is too big :(

Thanks

Tim

[Black02SS]

You need to make a file in LogWorks as well and double check that at idle with Live. This way you can take a nice 10min average of the car at full operating tempertature and average both logs. You will not get a voltage reading from LogWorks, only the afr. But you can back calculate the formula if you have the Actual AFR from LogWorks and the actual voltage and AFR from Live. Also, I would take a MultiMeter and double check the output from the LM1's 0-5v and see if it is the same as live shows. Grounds are really important. You might see 1.5 on the LM1 and 1.6 on Live. That .1 makes a difference in the formula.

[Extinct]

I was thinking it might be a ground offset issue, however I wouldn't have expected the differences to be as big as they turned out to be :shock:

[Black02SS]

I was thinking it might be a ground offset issue, however I wouldn't have expected the differences to be as big as they turned out to be :shock:

They might not be that much. You need to verify it with the log from the LM1. You could have an average of 13.2 on the Lm1 and 13.3 on Live, wich is within the limits if you ask me.

[Extinct]

That still does not explain why the AD1 voltage Live is reporting is so different than the H02 voltage the PCM is reporting ?

[Black02SS]

That is why you use the LM1 because the NB isn't accurate only to around stoich. Did you turn the O2's off and make it run only in Open Loop?

[Extinct]

I did make it run OL, however that still does not explain why Live would report one voltage for AD1, and the PCM would report a different H02 voltage, when they are both connected to the same output wire from the LM1, unless it is a ground offset, but I would not expect a ground offset to be that big ?

Since I have it in the pass side ( and assuming #1 cyl is still on the DS for US spec (camaro) cars :D), then H02S21 voltage should be the same voltage as the AD1, because I have the NB output from the LM1 plugged into the AD1 junction, and I have the purple wire of the pass side 02 (H02S21 I assume) plugged into the exact same junction on the flashscan box.

As you can see the H02S21 barely varies at all, while AD1 jumps all over the place.

[Black02SS]

If you are expecting AD1 to display the same voltage as your narrowband oxygen sensor, it won't. You need to dismiss looking at the stock O2's as they aren't going to tell you anything, especially in OL.

[Extinct]

hmm, I don't think I am being clear. Let me try again.

The NB on the pass side is out. The LM1 is in. I have the LM1 set to send an output voltage that simulates the NB. I have that output wire plugged into the flashscan box AD1 input and also into the PCM H02S21 input. Live is apparently reporting these voltages as different, even though they are coming off of the output from the LM1 ???

[Extinct]

Looked at it some more tonight. I understand why the differences aren't important in OL, but I was just curious for the event, lets say I want to use the LM1 to simulate my NB.

Anyway, did a short log with the engine off, Measured the two PCM NB voltages and the AD1 voltage. There was quite a difference. Only think I can figure is that the PCM must apply some kind of resistance reduction of reported voltage.

Just a curious thing, I don't think I would use the LM1 to run CL simulating a NB until I figure this out a little more.

[Extinct]

OK, would like to bring this thread back to life again.

I have been using the LM1 for the last several days on my stock tune. After running for a little while, I am getting DTC PO154, Insufficient activity.

I suspected something would happen because the voltages were so different between the LM1 simulated NB and my stock one on the other side.

I don't really know that much about the normal NB output curve of stock 02's, I just used the LM1 default. Anyone know if it is correct, or why I might be having this problem ?

I wanted to use the NB simulation to confirm my LTFT's were where they should be.

BTW, went back and confirmed the data in my earlier post, the NB channel was on AD2, so I had the LM1 channel one outputing the NB sim and that hooked to AD2 on Live and to the purple wire on the wiring harness, which is H02S11.

[Blacky]

Do you have your NB analog voltage set up like the attached image?
That is what the PCM expects to see.

[Extinct]

I do, however after looking at the data more, I think that I must have some sort of loose connection to the NB input on the car. Tonight I am going to get under it and check everything, then set up the LM1 to command a couple of set voltages, .5, .75, 1.0, while I monitor the H02S21 inputs and verify that it is reading them correctly.

I will report back my findings !

[Extinct]

Ok, checked this out tonight. First thing I did was program the LM1 to command .75 volts all the time. Connected Live and read the voltage on AD1 - .76 volts - looked at H02S21 - .445 volts as reported by the pcm. So I checked the voltage at AD1 to chassis ground, .82 volts. Got under the car, checked the voltage at the connector - .82 volts to ground.

So the LM1 is sending the .82 volts to the 02 connector, but the PCM is reading .445 all the time - doesn't change, and as a result I get the switching error. Why is that ?

Also, I checked the voltage from the H02S21 high (purple)wire, with the LM1 connected, to the H02S21 low (tan) wire, -4.0 volts ????

I'm lost at this point, anyone have any ideas ?

[GMPX]

I never really looked into it too much because I still have my NBO2 in place along side the WBO2, but I think the problem is the NBO2 sensor ground is not the same ground the rest of the sensors use, it sort of 'floats'.
So connecting just the NBO2 simulated output to the PCM is like connecting a signal without a ground connection.
What I don't know and maybe the LM1 people could answer this, is what happens if you connect a ground from the WBO2 to the PCM's O2 sensor ground?. It might be worth asking.

Cheers,
Ross

[Extinct]

That's why I measured the voltage difference between the sensor ground to the PCM and the simulated NB output. I was shocked to see -4.0 volts, it made me a little bit scared to hook them up. I did run a wire from the NB sensor ground (tan) wire up to the area where I have the LM1, but I did not connect them. So far I have not read any threads where anyone is actually using the LM1 to sim the NB, so I couldn't get any info as to whether I should connect the two.

I am going to contact Klaus at Innovate and get his thoughts ;)

[Extinct]

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 to all for the responses !