wideband datalogging with the LT8s
 

so i've been cleaning up my maps but i have been hammering my head into the wall trying to figure out how i can datalog my techedge 1.0 in sync with my LT8s, i know it would be much easier if i would have just dropped the money for a LMC1 wideband and have it spit out a 0-1.0volt reference and log that but i am stuck with what i have. so tuning by hand has it's limits and now i need to figure out how i can log with this wideband and sync it with my logs from the microtech.

how do you guys have your logging setup? please give some references and what type of logging software you are using/how do you have the RPM trigger setup?

I take it the Techedge oututs a 0-5V signal?

I am going to have a similar problem with the Nexus wideband I will be using. My plan was to just use a voltage divider to divide down the 0-5V signal five times.

yep, it is just a 0-5volt wideband signal and techedge has basically no datalogging support so i'm trying to figure out what a good setup would be.

Voltage divider. Just a few resistors. For example:

http://hyperphysics.phy-astr.gsu.edu...ele/voldiv.gif

http://hyperphysics.phy-astr.gsu.edu...ic/voldiv.html

This can give a linear 0-1V output from a 0-5V input. Of course that's not exactly the same as a narrowband but it will be good for datalogging.

Radio shack carry voltage dividers?

It's something you would make yourself with a few resistors. The page I linked to has the basics in what you need to calculate to get the voltage you want. For a load, pick a fixed load (of say, a 10K resistor) since the Microtech's O2 sensor input is seriously high impedance and represents virtually no load.

there still must be a more accurate way to tune with the LT8 though without doing something like this. how do most tuners datalog and time everything while tuning with the LT8?

'til now i just log the wideband and wing the fuel timing corrections but there has to be an easier way without needing to try and log with the wideband input into the microtech software.

If the wideband had a 0-1V output, then it would be easy. :) That's the only thing that annoys me about the Microtech: O2 input is fixed at 0-1V.

The voltage divider should be fine though since all you are doing is dividing the 0-5V down to 0-1V. If you use 1% resistors you will be more accurate then the sensor could ever hope of being.

I was thinking about this last night as I was building a dual LM1815 circuit for a Megasquirt...

If you follow the advice I gave you, you may blow your engine. I screwed up and forgot that a wideband's output is opposite of a narrowband. Low voltage means rich, high voltage means lean. Opposite of what the narrowband input of the Microtech is expecting...

So, if your wideband can output a properly polarised 0-5V output where rich is 5V and lean is 0V, then the voltage divider will work.

Otherwise, the signal needs to be inverted. There are several options to do this with just a few transistors but an op-amp based inverting amplifier is probably the most stable choice.

the microtech narrowband input it basically just for highway tuning, it doesn't use a closed loop like you may be thinking, basically is it just there to give you an AFR number through the microtech but it does not interact with the programming. if i do step down the voltage i would double check it with the wideband to be sure the voltage matches the AFR numbers i would expect from that voltage range so no worries. :)

I know there's no closed loop, I just don't want you looking at a voltage and thinking you are rich when you really are lean. :)