Toyota Aygo Wideband O2 sensor retrofit & piggyback or OBD2

[aygomodder]

Hi all,

I have a Toyota Aygo on gasoline and I want to retrofit a wideband O2 Sensor in it, to be able to make lean burn possible. I dont want to do any changes to ECU.

Idea: I read through sensors or OBD2 (with Arduino) throttleposition (0 – 100%) and RPM. If load < 45 and rpm between 1500 and 3000, I will return to the ECU a fake signal. If measured (real) AFR > 16, then I will report 0V, if below 16, I will report 1V. Otherwise I will return the normal AFR (I don't want to mess with it).

Questions:
1. does this make sense; I've read on some other cars that its possible but I think most will also modify their ECU (which I dont plan to do) . On the wiki there's an article called "Lean burn" by Oilpan 4 (1984 Chevy suburban 454 ) (I cant post links?) and it seems to agree.

2. will it blow up or damage my engine, or wreck the valves? I do not want to go crazy lean like some Hondas (20 AFR). 16 is good enough.

Rgs
Cas

[serialk11r]

You need to emulate the post-cat sensor (it will just read 0V all the time and throw a code), and ideally change the ignition timing, and ideally also run richer at WOT or tweak a combination of other things so that at WOT you don't burn the valves.

[aygomodder]

Ah smart!! Thanks Because I run lean, more O2 will be in the mixture (both pre/post-cat) and thus also the post-cat will also be lean (0V). So then I need to return 1V always if I'm in lean-burn for post-cat converter (can be narrow-band), to tell the ECU all O2 is bound (e.g. N2O). Nice idea.

I'll change it then to a full AFR map, including all values to have more control (including WOT). Ignition timing is not possible for me now I do not want to mess with ECU yet..


Do you perhaps have a guess-timate how much % fuel only the AFR map would save, and separately how much the ignition timing would ? Makes it easier for me where to put the priority on. Thanks!!