LC2 into whodwho MS2 box?

[CorvallisBMW]

I'm trying to figure out how to incorporate my LC2 in to my new whodwho MS2 box. The primary output from the LC2 is running my George Graves stealth AFR display, but I also want it to talk to MS for tuning capabilities. How do I make this happen? THe LC2 has 2 outputs, which according to their website:

*Two fully programmable linear analog outputs to connect to analog gauges, dyno computers, ECUs, piggyback controllers, and other devices with analog inputs. Analog Output #1 (Yellow) is configured as 0 volt = 7.35 AFR and 5 volts = 22.39 AFR; Analog Output #2 (Brown) 1.1 volt = 14 AFR and .1 volt = 15 AFR. With the provided LM Programmer software these analog outputs may also be configured by the user.

But I'm unsure of how or where to input this signal in to the MS2 box. Anyone have experience in this and can give me some pointers?

[whodwho]

Just take an old O2 sensor and cut off the connector and feed it from the 2nd output of the WB controller. I have some documentation on the disk that can help

[CorvallisBMW]

I'm a little confused by that so let me see if I'm understanding you correctly:

Take the factory O2 sensor, cut off the sensor pigtail near the female connector (where the sensor ties into the harness) and feed the signal wire on that female connector with the output from the WB.

Basically substituting the factory O2 signal with the signal from the WB controller, and keeping the factory harness/wiring intact. Yes?

It makes sense in my head, but before I start cutting and hacking I want to make sure I get it.

Oh and I suppose I'll also have to change the WB controller on that output from 0.1-1.1V to 0-5V, since the other 0-5V signal is occupied with the GG display.

[ak-]

Pretty much.

You have:
Red: 12v (I used the defroster switch)
Black: ground (ECU shock tower ground)
Yellow: output 1 (Capped this off - you can use it on the GG display)
Brown: output 2 (To the stock o2 signal wire AND AFR gauge signal wire.)

And yes change both them to 0-5V to get wideband info rather than narrowband on the gauge and GG display.

All other grounds associated with the gauge/wideband should be grounded on the same original ECU ground on the shock tower to keep Megasquirt's Tunerstudio display happy.

I have an LC1, but the wiring is practically the same when talking about Analog outputs and what not.

edit: put a 5A fuse inline of your 12v source

[CorvallisBMW]

Alright, got it. I just spliced in to the Pin 28/Black wire as it came out of the ECU 55-pin plug. Easy. (I also changed the output on that LC2 channel from 0.1-1.1V to 0-5V)

I noticed though that I have the LC2 grounded to the chassis under the dash... I guess I'll need to route that ground to the shock tower.

[ak-]

Alright, got it. I just spliced in to the Pin 28/Black wire as it came out of the ECU 55-pin plug. Easy.

I noticed though that I have the LC2 grounded to the chassis under the dash... I guess I'll need to route that ground to the shock tower.

Yeah, I had one or more things grounded on a nut near the console and tunerstudio didn't like it. AFR from the gauge and tunerstudio were off by 0.1 - 1.0 or so.

[CorvallisBMW]

Insane how tenths or hundredths of a volt can throw it off by that much. But I guess when your'e dealing with 5V of signal and 15 points of AFR, a small variation can have a big effect.

[CorvallisBMW]

Update: If you're using an m20 harness, make sure you trace the black wire coming out of Pin 28 and not the black wire in the harness itself! If you look downstream of the plug at the ECU harness, you'll see only 1 black wire; but it's not the O2 wire! It's actually the tach signal wire. The black wire from Pin 28 gets bundled with several other wires and then covered in a black sheath where you can't see it, so you have to open up the plug and pull that wire out of the sheath in order to tap in to it.

[whodwho]

Couldn't you of just connected it to the stock O2 plug?

[CorvallisBMW]

Potentially yes, but it would have been fairly involved. The wideband sensor still has to go through the LC2 controller in order to operate correctly, because the wideband uses a 0-5V signal, whereas the factory O2 uses a 1V-0.1V signal. So I would have to take one of the LC2 output wires, run it back through the firewall, attach a connector of some kind, and plug it in to the factory plug. Seemed easier just to take care of it all in the glove box since that's where my LC2 was mounted anyway.