Poor fuel consumption FZJ80 (1 Viewer)

[robnicko]

An EFI system with no o2 sensor would essentially be running blind.

The o2 sensors upstream of catalytic converters allow the EFI system to determine how fully the fuel is combusting so that it can adjust the air-fuel ratio to get closer to the ideal 14.7:1 without running too lean.

Without the feedback, it's running without a feedback loop. What is referred to as "open loop".

Since running too lean will destroy the engine but running too rich won't, the open-loop program typically runs rich. It also tends to retard timing but i assume you have knock sensors so perhaps the ozzy ecu doesn't do that to you.

The o2 sensors downstream of the catalytic converter exist entirely to determine if the catalyst works properly.

You will find that most 80's in Aus do not have O2 sensors. Something to do with the compliance regs etc back then but in hindsight a good thing as its less things to go wrong with them.
They do run an Open Loop calibration as opposed to closed (except for when coolant temps are very low and enrichment applied) and rely on the MAF & other sensors such as coolant temp etc to maintain an ideal stoich of 14.7 and knock sensors for timing etc. This is where the CO2 adjuster comes into play for setting the 'mixture' however a GAS Analyser required to set. Most EFI in cars these days run a combination of open & closed loop due to the majority of O2 Sensors being installed from the factory are narrow band as opposed to wide band.

Agreed its not the best way to run EFI but mine still running like the day i bought it new, consistent fuel consumption of around 13-15L/100km and nearing 560,000 kms and wouldn't change anything