Checking A/F Ratio on your car?

[ra23celica]

You need a high end Multimeter like a Fluke 87 or similar that can do MIN/MAX/AVG readings over a very short period of time. These can be used to test the Ox terminal on your DIAG connector. I recently put this to the test on a friends car and it works. 0.2MIN, 0.6 MAX and a 0.45volts average. Spot on.

MacroP,
This is exactly what I need. Can I book my car into your work for this test please? And how much beer do I bring?
Thanks,
Mitch.

[MacroP]

MacroP,
This is exactly what I need. Can I book my car into your work for this test please? And how much beer do I bring?
Thanks,
Mitch.

Sorry dude, I'm a couple of hours from the city plus I'm out in the sticks at a minesite at the moment. I reckon your best bet for now would be to go down to one of those Ultratune or similar mobs and tell them what you want exactly. I'd imagine they'll have some sort of analysing equipment setup that will read the O2 sensor, in fact it should be a straight forward test for them, and something that can be done very quickly. Their equipment may have a visual graph output so you can see the fluctuations and reading, basically an oscilloscope for vehicles.
Having never been to one of these places I'm only assuming.

Good luck

[30psi 4agte]

I use to work for ultra tune and can vouch that they have the equipment to test it!

[ra23celica]

Thanks for the heads up guys (MacroP and 30psi 4agte), I have noticed Ultratune pushing themselves hard on the TV lately so I will find one of them locally and get a bit of good old fashioned service going! Cheers,
Mitch.

[CrUZida]

Mitch, take the car to Balcatta EFI Automotives, PLEASE, or somewhere that Clint recommends.

While I'm all for sorting out problems myself, there comes a time where you hand the car to someone who knows what they are doing, wait awhile, and then get back a perfectly working car (hopefully) and enjoy it.

You have spent WAY TOO LONG trouble shooting this car, its time to 'give up' purely so you can actually enjoy it.

[gixer]

exhaust gas sensors used in the '80's were not wideband O2 sensors but used gas spectography to work out the analysis, wideband O2 is fairly new in comparison, we have a number of older gas analyzers(gas spectography/infared type) they measure a lot more gases than just oxygen, ours measure CO, CO2, O2, HC, NOx, they are also quite slow and don't like full load exhaust temperatures on them, we also have a number of narrowband which we don't use for tuning(not acurate enough) and a nice Autronic wideband on our dyno.

[ra23celica]

Mitch, take the car to Balcatta EFI Automotives, PLEASE, or somewhere that Clint recommends.

While I'm all for sorting out problems myself, there comes a time where you hand the car to someone who knows what they are doing, wait awhile, and then get back a perfectly working car (hopefully) and enjoy it.

You have spent WAY TOO LONG trouble shooting this car, its time to 'give up' purely so you can actually enjoy it.

Damn you the voice of reason in my head, do you give JCMF this sort of good advice as well?!

When I first spoke to EFI Auto's in Balcatta (who cleaned my injectors for me) they did not sound too confident about my car, but if you and JCMF went better after going there I had better give them a call.

Speaking of calling I tried two Ultratunes today and got fobbed off by both of them "too hard for us mate"......

Got to be some better people than this around...

[JustCallMeOrlando]

Got to be some better people than this around...

There is, EFI Autos in Balcatta, do it.

[CrUZida]

If you have a factory ecu, EFI auto's are happy to play with it.

They *should* find the fault, providing your ecu was correctly wired.

[camrygt?]

I'm a little confused by this thread. The output of any narrowband O2 sensor (be it a 1 wire 4 wire 3 wire whatever) can be read by any mulitmeter as the voltage simply represents the A/F ratio.
If the output varies (pulses whatever) between 0 ish and 1 ish volts then either the ECU is in closed loop and varing the fuel to maintain an average of about 0.5 volts (14.7 AR) or the car has a problem causing the AR to vary in a uncontrolled way.

the difference between 1 and four wire sensors is only the heater plus a ground which has no effect on how you read them only they are slightly more accurate and get to operating temp faster.

So using any multimeter the signal wire from your o2 sensor should fluctuate between close to 0 and close to 1 up to about 5 times a second under cruise conditions and possibly idle.
Under a constant full throttle condition and or boost the voltage should go to one of the extremes and stay there (I can't remember if 0 or 1 volt indicates rich someone one here will know) Generally a varing voltage under cruise means the o2 sensor is working and the ecu has gone into closed loop mode which is normal. On a wideband O2 this usually reads a constant 14.7 but in reality it is varing between something like 14.4 and 15.0 rapily.

The expensive "special" machines to read these are only volt meters anyway so don't waste your time.

Remember a narrowband o2 sensor is only accurate between about 14.3 and 15 to 1 so get a wideband gauge like the techedge ones if you really want to know what is going on

[urantia]

I was under the assumption the average mulimeter is not quick enough to measure the voltage fluctations on a narrowband o2 sensor (thus my suggestion of using an analogue multimeter)

[JetspeedCamry]

I'm a little confused by this thread. The output of any narrowband O2 sensor (be it a 1 wire 4 wire 3 wire whatever) can be read by any mulitmeter as the voltage simply represents the A/F ratio.
If the output varies (pulses whatever) between 0 ish and 1 ish volts then either the ECU is in closed loop and varing the fuel to maintain an average of about 0.5 volts (14.7 AR) or the car has a problem causing the AR to vary in a uncontrolled way.

the difference between 1 and four wire sensors is only the heater plus a ground which has no effect on how you read them only they are slightly more accurate and get to operating temp faster.

So using any multimeter the signal wire from your o2 sensor should fluctuate between close to 0 and close to 1 up to about 5 times a second under cruise conditions and possibly idle.
Under a constant full throttle condition and or boost the voltage should go to one of the extremes and stay there (I can't remember if 0 or 1 volt indicates rich someone one here will know) Generally a varing voltage under cruise means the o2 sensor is working and the ecu has gone into closed loop mode which is normal. On a wideband O2 this usually reads a constant 14.7 but in reality it is varing between something like 14.4 and 15.0 rapily.

The expensive "special" machines to read these are only volt meters anyway so don't waste your time.

Remember a narrowband o2 sensor is only accurate between about 14.3 and 15 to 1 so get a wideband gauge like the techedge ones if you really want to know what is going on

Exactly what i thought..hence why a simple Autometer AFR guage works...all it is is a dramaticised voltmeter...0V-1V scale.

[TwentyTwo]

Why not use a decent multimeter that can give you the average voltage? I got one for $40 from Dick Smith's, it can display the ave. volts on a histogram.