Air to Fuel Ratio Gauge

[Nzpure]

How does one hook up a air fuel ratio gauge on a vs up?

[axemurderer101]

on mine it was 3 wires power, earth and sensor wire which i tapped into one of the oxy sensor wires at the ecu

[VSIIBerlinaL67]

which wire at the ecu?

[Tasmaniak]

you need to tag it into one the pre cat sensors for the pretty light display which will tell you nothing, and the post cat sensor for even more nothing..a stationary light

[Cheap6]

One could ask first what type of air fuel ratio gauge?

If it is the 'pretty lights' LED type, the green (signal) wire on the meter goes to the grey/yellow from the sensor (spliced). The red goes to ignition switched power and the black to earth.

That will tell you whether it is rich or lean, how quickly the O2 sensor is responding (switching from rich to lean and back) and if you swap it from side to side (or, I guess, hook two up) allow comparison between the O2 sensors on either side. (Only one may be dead). It will also tell you when you are running in closed loop and open loop and when decel. fuel cut is occurring.

It won't tell you what fuel mixture you are running but can be considered a cheap diagnostic tool. I don't consider that nothing.

If it's a more expensive A:F gauge, the manufacturer should have provided installation instructions so I'm guessing it's not one of those. They will usually need the wide band sensor subbed in for one of the original sensors and a narrow band substitute signal from the meter sent to the PCM though.

(What post cat. O2 sensor)?

[axemurderer101]

there is 3 plugs on the ecu, on the pink plug you can tap into either D13 (grey wire) or D15 (violet wire) i think i tapped into the D15 which is the right oxy sensor

[TUF UTE]

i made a booboo with mine lol... i tried to tap it into the brown wire on my 5L where the gas system tapped into it ... killed the gauge

[Tasmaniak]

That will tell you whether it is rich or lean, how quickly the O2 sensor is responding (switching from rich to lean and back) and if you swap it from side to side (or, I guess, hook two up) allow comparison between the O2 sensors on either side. (Only one may be dead). It will also tell you when you are running in closed loop and open loop and when decel. fuel cut is occurring.

It won't tell you what fuel mixture you are running but can be considered a cheap diagnostic tool. I don't consider that nothing.

If it's a more expensive A:F gauge, the manufacturer should have provided installation instructions so I'm guessing it's not one of those. They will usually need the wide band sensor subbed in for one of the original sensors and a narrow band substitute signal from the meter sent to the PCM though.

(What post cat. O2 sensor)?

How can you use it as a cheap diagnostic tool? it swings left to right to show that the o2 sensor is working correctly if it slows down drastically one day you need to replace it...sometime in the 2 years before it fails completly. Fuel cut happens EVERYTIME you let off the pedal...gauranteed...use a vac gauge.

just an FYI in regards to post cat sensor....it's a MY97 meaning it's OBDII so it must have a post cat sensor.

[Cheap6]

How can you use it as a cheap diagnostic tool? it swings left to right to show that the o2 sensor is working correctly if it slows down drastically one day you need to replace it...sometime in the 2 years before it fails completly. Fuel cut happens EVERYTIME you let off the pedal...gauranteed...use a vac gauge.

just an FYI in regards to post cat sensor....it's a MY97 meaning it's OBDII so it must have a post cat sensor.

The rich lean swing and the rate of that swing is exactly why it's useful as a diagnostic tool. If you are familiar with the normal rate of swing you can make a reasonable assessment of the condition of the sensor. Interpreted correctly, it's the ghetto oscilloscope. It's not an oscilloscope of course, but it's not $1K either.

Fuel cut happens under fairly specific circumstances. The engine needs to be above 80C, engine rpm > 1400, VSS > 42km/h, TPS < 2%, MAF < 109 gm/s. (Yes, I had to look that up). As an example, let's say the fuel cut disappears, as observed on the LED display, when you would normally see it occur. Time to start looking for a fault in one of those inputs to the PCM, whether it sets a code or not. The information is there, you just have to interpret it correctly.

VS II is not OBD II (nor is any V6 Commodore up to at least VX) and only has two pre-cat. O2 sensors - one for each of the left and right cylinder banks.

I have D13 as grey/yellow and the RH sensor. The violet into D15 is the LH one. Either will work but only yield information about that bank.

[Tasmaniak]

wait a minute? when did Australia make it law that OBDII was to be a Standard? (I've been in the US for a VERY long time. It was mandatory in 96)

We are refering to different types of fuel cut...fuel cut on OBDII should happen anytime the TPS sees 0% from anthing above 5% and obviously must be in closed loop operation.

[Cheap6]

The short answer is that as a diagnostic standard only, Australia made OBD II compulsory from Jan. 2006. The underlying emission standard was never required here and the last US based emission ADR was 37/01 which is similar to US 1981, I think. That was new models 1996 and all models 1997. Subsequent to that our emission ADRS have been based on European standards.

Some cars, including some Holdens, sold prior to 2006 do use the OBD II diagnostic protocols though.