O2 sensor & AFR reading ????

[tasroadster]

Can I connect an AFR meter and O2 sensor to the factory O2 sensor bung?

And do a reading without the factory sensor NOT connected.

I have Turbo NA6, an wondering if not having the closed loop O2 sensor connected (factory setup) that this may alter the real reading (due to the ecu wondering what the hell the O2 sensor is doing ??) .......maybe the turbo has altered this situation ????????

Thanks for the help.

[Boags]

When did you put the turbo on? The last one of your posts I read was that you were looking for a kit...

Why are you taking the O2 sensor out? Just attach your AFR guage to the factory one. The computer will sh*t itself without an O2 sensor plugged in.

Boags

[tasroadster]

I decided on the Greddy Kit...........if this is only 6psi boost, just can't imagine what 12 psi or anything higher would be like......insane......


Great kit...... Easy to fit.....No fuss.........goes VERY VERY well straight out of the box. Don't need a new clutch....just a great product.

I have an Innovate AFR meter which has a 5 channel data recorder, just wanted to know what the AFR was doing, I also have a knock sensor which hasn't been flashing at me with the kit installed. So all is well.

I am totally impressed with the simple kit and the staggering performance of an MX5 at just 6psi. After years of 7200 7200 7200 around symmons Plains in normally aspirated form this is jus Soooooo great.

Thanks

[Fatty]

i fitted my el cheapo jaycar a/f meter directly to the factory o2 sensor, spliced into the wire. after a few days i disconnected the o2 sensor from the ecu, and the car ran fine. i did this coz i wanted to stop the car going into closed loop. the problem was that my a/f meter readings were all garbage, because the factory o2 sensor is very sensitive to the load being put on it by ecu, so once it was disconnected the o2 sensor could not operate properly. i did not drive the car , i just sat in the garage and revved it a bit. it did not sh*t itself or go into limp mode or anything like that, so i can't see why your idea wouldn't work.

[Boags]

Hmmm. I would have thought that without the O2 sensor there the computer would think that the engine is running VERY lean, ie. no fuel at all, and then richen the hell out of things, or just cease to work...

I've been wrong before though Why not connect your new O2 sensor into the ecu?

I'm glad you're so impressed with your new setup! Makes me wish I had the cash to splurge! There are heaps of easy upgrades for that kit aswell, like timing control devices, which will free heaps of horsies down low... Have you had it dynoed?

Boags

[Fatty]

nah from what i understand, without the o2 sensor the ecu just stays in open loop mode and uses it's fueling tables to decide how much fuel to deliver, based on the afm info. you could drive around forever without the o2 sensor attached, but your fuel economy would go out the window. closed loop is much more fuel efficient.

[Matty]

The engine and ECU can run fine without the O2 sensor connected.

The sensor voltage takes a while to come up from 0 anyway, and nothing will happen until you have the car over 2000? rpm for more than 30 seconds constantly. Only then does the ECU record a fault code that the signal from the O2 sensor is lower than it should be.

Luckily low voltage on the sensor corresponds to a lean mixture, so the ECU will attempt to make it run richer to increase the voltage (but this will never happen when it's not connected).

There is a limit on how much richer it will make it though, some percentage of the default injection duty cycle. It won't keep making it infinitely richer...

However if you're trying to log AFRs I think you'll find that the removal of the standard O2 sensor will (as described above) affect the reading you get from the other sensor...

Afterwards, you'll have to clear the fault code from the ECU, nothing harder than disconnecting the battery and standing on the brakes to drain the charge.

[4sfed5]

NO NO NO NO NO NO!!!

You MUST keep the o2 sensor in as it is used all the time. at any throttle position below 4000rpm the car runs off the 02 sensor so you must leave it connected to get accurate tuning results...otherwise the car will go into limp home mode and your afrs wont be indicitive of your actual tune.....


Having said that....most of the innovate wide band units have a narrow band output that you can connect to your ecu when you use your innovate sensor so check your manual.

[Matty]

NO NO NO NO NO NO!!!

You MUST keep the o2 sensor in as it is used all the time. at any throttle position below 4000rpm the car runs off the 02 sensor so you must leave it connected to get accurate tuning results...otherwise the car will go into limp home mode and your afrs wont be indicitive of your actual tune.....


Having said that....most of the innovate wide band units have a narrow band output that you can connect to your ecu when you use your innovate sensor so check your manual.

I can't say I've ever unplugged my O2 sensor, but the effect (on output signal) would be identical to having a dead one, and I've had two of those. The effect really isn't much...

[4sfed5]

whats the point in tuning a car that isnt running correctly in the first place??????

Disconnecting an o2 sensor is definitly going to alter the tune of the car as it runs in closed loop at ANY throttle position under 4000rpm even at wide open throttle under 4000 rpm its running off the o2 sensor.

its just madness to put your car into limp home mode then \"tune\" it then reconnect the o2 sensor. the results are useless.

[Sean]

I have an Innovate AFR meter which has a 5 channel data recorder, just wanted to know what the AFR was doing, I also have a knock sensor which hasn't been flashing at me with the kit installed. So all is well.

If I recall correctly the innovative is a wideband and is VERY popular in the USA. Depedning on teh model they actually have a narrowband signal output too, so you might be able to get the best of both worlds and feed the narrowband signal back into the ECU anyway?

[Okibi]

Yeah I've been considering using one of these style products so I can stick in a wide band sensor (to monitor) but output a \"narrow band\" signal for the ECU.

I'd be interested to hear what you've come up with.