LC-1 Wideband, MS2Extra and stock wiring

[alan1977]

Hi, this is as installed on my 95 bmw 525i having a bit of a headache with this one
So, i have megasquirt 2, and an adaptor harnass in the original dme (ecu) housing.
currently i have everything working, now i want to intergrate the wideband controller.
the lc-1 is a long lead with the controller built into it, i also have a wideband gauge to fit, but that is out of scope of this thread for the moment

I have an old o2 sensor plug here to modify and splice to the end of the Lc-1 harnass. so i can plug and play into the stock loom.

See below for clicky for big diagrams of the stock o2 wiring and the lc-1 wiring,


12v switched is easy, thats coming of the o2 heater relay, which i currently have running all the time with the key on, so +12v goes to pin 4 on the o2 sensor plug

Analog output 2 wants to go to pin 2 on the o2 plug (to pin 13 on the dme plug)

now, according to the lc-1 diagrams, all grounds want to be sent to the same place, in my mind the grounds want to be near the ecu (and the documentation suggests something similar)
So, does that mean i can safely gather all the lc1 grounds and wire them through pin 1 on the o2 plug (going to pin 40 on the dme), or is this a bad idea?

my concern is too much current from the heater running through the loom to the dme harnass adaptor.
I am thinking i should seperate the grounds out somehow, but hte seonsor/system ground should still be at the dme or near it.

Any thoughts on an easy way to do this? oh it would also be apositive bonus if the wideband controller can be left wired so that it is communicating with the stock dme...

[rickb794]

I have been told you should not ground the O2 heater to the signal ground.

But the O2 signal ground should return to the MS signal ground to insure an accurate reading.

I think the default configuration of the LC-1 gives a narrow band output on the brown wire.
You will have to reconfigure it or use the yellow for a 1-5 signal to the MS.

[alan1977]

yer i will use the brown wire as diagrammed, i'll do whatever else is required for the gauge later on
see. i thought you would want to ground it else where also, but hte manual specifically says the opposite (diagram is from the manual)
i can happily ground through pin3 (shown in diagram as the heater earth) but i dont understand whty the manual suggests this to be wrong :S
and run the system and calibration line through pin one on the stock connector, which end up at my harnass adaptor, and thus easier to ground hte gauge to the same location.

[alan1977]

ok i just read further
it says :
c. Vehicle has a 3-wire sensor:
Typically the 3 wires are: heater power, Ground, and sensor element connection.
Generally they have 1 black wire and 2 white wires. Connect the black wire from the EFI
computer to analog output 1 of the meter. Leave the other wires unconnected but make sure they
cannot contact any metal parts or see above. If the wiring colors are different, then heater power
can simply be determined by measuring the voltage on the wires when the engine is running. The
wire showing 12V or more is the heater power. The sensor element connection voltage fluctuates
around 0.45V when the car is warmed up. Wire analog output 1 directly to this wire. The Ground
connection has low resistance to chassis ground (less than 1 Ohm). Measure while the engine is
off.

d. Vehicle has a 4-wire sensor
Typically the 4 wires are: heater power, heat er ground, sensor ground, and sensor element
connection. Proceed as for the 3-wire sensor.

so i have a 4 wire sensor, its suggesting wiring as above, but only using one of the grounds, which would be the one back to the ecu right? as my ms o2 sensor ground is at that location also
it does say to use analog output 1 :S while the diagram shows 2... i assume im going to have to reprogram one of the outputs as the gauge and stock computer want a standard analog input
is MS happy with the standard analog input also?

[alan1977]

conflicting documentation
seems the brown should conenct to the gauge 0v = 7.35 A/F and 5v = 22.39 A/F

And the yellow 1.1V = 14 AFR and .1V = 15 AFR. This is a simulated narrowband signal

is the 0-2v signal adequate for a wideband input on MS? is htere any disadvatage to using the 0-5v signal option? obviosuly keepign a simulated narrowband menas my ms and stock ecu is plug and play

[lowgman]

FWIW, I ground the heater to a seperate ground than the sensor ground. My sensor ground went onto the same wire that my MS2 is grounded to (which is the engine block)

After a while, I bought the Innovate DB gauge and ground that onto the same wire that went to the MS2 ground. If I didn't do that, my MS2 and the DB gauge had slightly different O2 readings (it's still off right now, but only by .1 or something like that)

The two analog outputs for the LC-1 are programmable. I made the mistake of making them both wideband signals before I got the gauge and it took me a while to figure out which output to change to the narrowband signal.

[alan1977]

ok this is doing my head in grr

so the original loom method yielded no results
so i disconnected it and broght the wires right up to megasquirt
i earthed right next to MS on the metael ebox where all my earths go to
i took a live straight off the relay
i connected the brown lc-1 wire (0-5v default apparently) directly to the pink wire that the o2 sensor is on for MS

i have ms set to show up the voltage on the o2 line, i assume thats absolute with no scaling or skewing
the voltage line still reads 0.3v
disconnected it reads 0.2 v (its either 0.3/2 or 0.03/02 i forget)
with the brown lc-1 wire disconnected im getting around 0.250v on the brown wire... when i connect it to MS it drops to 0.45v

when connected it the voltage remains constant, then randomly jumps around for a few seconds
at one point i had ego control on idle just to experiment, and the afr's did swing around for a minute, was quite slow to catch up but that was a one off

So, to clarify, in MS i should be using either lc-1 default, or lc-1 0-5v 10-22:1
so presumably if i was uper rich at idle it would be nigh on 0v, but id expect it to swing to a few volts, i had ego amount set to 25% with the thought it must make an impact

im probably missing somethign really basic

just to clarify, my megasquirt is grounded to a screw on the metal ebox
i grounded both lc-1 grounds to the same ebox (different screw)
12v feed direct from a relay, measured 13-14v at idle

ohh.....

when i was measuring the voltage on the brown wire i was using the MS ground as negative, i should have taken it to the LC1 ground and seen if htere was any difference right?

[aut0m4tic1]

FWIW, the LC-1 outputs are both programmable. I run analog out 1 through my stock harness and analog out 2 to a gauge. hook up the lc-1 to the pc. Start LM programmer and verify the parameters. make sure one of them is set to 0v-7.35 5v-22.39. Your wiring diagram should show which wire is signal and which is ground. Ground the signal ground and all the lc-1 grounds together. choose single wideband in TS and calibrate it for the default lc-1 (0-5v) if TS reads different than logworks, you have a ground offset and you need to move your ground. Prefferably where you ground your MS.

[alan1977]

ok spent some more time on this and convinced i either have a controller or sensor issue
basicaly, on power on it all sits at low voltage, after 20-30 seconds it ramps up to 5v.... sits there for maybe 10 seconds, then drops back to reading low again
on a whole 30 min drive last night nothing..
so i've put my money on a shot sensor and ordered a brand new one (this was second hand grr)
so fingers crossed that's it

[16v dude]

Good information

[alan1977]

great got somewhere
replaced the sensor with a new one and re-calibrated
and bam...
thought for a minute it was still way off as my cruise bins were showing up super lean which i wasn't aware of
after richening up the cruise/midrange area i suddenly had less snatchyness when coming off and on the throttle
I had been trying to smooth that out previously with AE as i thought it felt right

Very happy at this point
Now i just need to go out and tidy up all the wiring again