MS1 MSnS-E 029t trying to run fuel only.

There are 2 guages on the list to display front and rear O2 voltages in MegaTune. but niether of mine are displaying the true O2 voltage. what's the deal?
i have 5v coming from the LC-1 controller, 4.97v going into the MegaSquirt at Pin #23, The rear bank O2 gauge shows 3.88v and the front bank gauge shows 2.3ish volts. the AFR gauge in MegaTune is showing 18.71 which coressponds with the 3.88v. The true readings should be 5v and 22.05 AFR. and why is the other O2 gauge even showing anything at all. i have the "second O2" setting turned off.

Thanks,

Craig

 

did you run a reference ground from the LC1 to the MS? If you don't wire everything right, then it won't work.

You have to run the heater ground on the LC1 to someplace on the chassis or engine, but the other two grounds must run to the megasquirt ground pins.... otherwise you can see problems like this.

Also, you have to be sure to set up megatune for the LC1 by changing the proper setting in settings.ini

The second guage will just show whatever, even if you have second O2 turned off, it'll just show you the value on the CPU pin that the second O2 WOULD come in on if you had it turned on.

Ken

 

megatune is configured properly.

can't i just ground the LC-1 to the same grounding locations as the megasquirt? wouldn't that have the same effect? currently i have the LC-1 grounded directly to the battery. heater ground has it's own wire, but the other two grounds are linked together and then grounded with a single terminal. Megasquirt it grounded to the block. I've read about voltage offsets, but damn, a whole 1.09v drop is no offset. i don't understand. the megasquirt it getting nearly 5v. what else does it need to know?

and the second O2 gauge that shows "whatever" changes when i adjust the O2 **** on the stim. both front and rear gauges move.

i know i asked for advice, and you're trying to help. and i'm not trying to argue with you. i just don't understand.... i'm doing to re-do my LC-1 grounds like you suggested. i really didn't want to cut the sheathing that the LC-1 harness is in.

this is my last hurdle before i start the tuning process.

 

You may have said this somewhere else before, but what version of the MS board are you running?

If you're using the 2.2 board, you also have to remove D11 from the MS to get an accurate reading.

If you have the 2nd O2 disabled, then ignore the guage value for it, it's not going to hurt anything.

 

V2.2 board. i typed a reply but thought it best to search the megamanual to see if it was on there somewhere. coudln't find anything about D11 and i guess i forgot to come back and hit submit. so i'm sorry for the delayed response.

thanks for your help though

Craig

 

It was posted a long time ago (maybe 1.5 years ago? before the v3 board came out) on the msefi forum. If nobody posted to that thread, it was probably then "cleaned up."

Trust me though, none of the v2.2 boards that I still have here have D11 installed.

The diode causes a voltage drop as the voltage gets closer to +5v. I think up to a 1.8V drop, although that number could be wrong.

 

removed D11 today. getting good signal now. 4.98v which reads as 21.99 AFR. close enough for me. it reads .02v low throughout the entire range. if i set the LC-1 to output 2.5v, the MS shows 2.48v. if i set it to .04v, the MS shows .02. and if i set it to .02v, the MS shows .00v. i'm going to have to assume that is a ground offset. but is something that slight even worth being concerned about?

 

I wouldn't worry about that... I don't think there's any way you can get rid of that slight of a difference.

 

BTW, thanks muy for your help.

it is much appreciated.

 

no problem!