O2 Sensor Help

[Marcus89]

I got my car tuned today and the tuner had to turn off the O2 sensor cause it had readings all over the place. At idle it had 0 but with a slight tap on the throttle it just jumped to max voltage.

Is this a sign of the O2 sensor being stuffed? I cut out the plug as it was melted and directly wired the O2 sensor is it possible that if I had the wires wrong it would cause these issues? i.e. white wire into black and black into white

[MagicMikeZ32]

What ecu?

[Ben C34]

Your tuner should have been able to explain to you normal O2 sensor behaviour, and if yours is stuffed. Why didn't he?

[jhjones]

Shouldn't ecu be in open loop at idle and closed loop on light throttle, cruise?

[Ben C34]

ecushould be in closed loop at idle

[blind_elk]

There's a sticky thread at the top of this General Maintenance section - have a read!

At idle, it probably doesn't matter if the ecu is running closed or open loop - there probably isn't sufficient gas flow for the sensor to work correctly. It's likely set quite lean, hence reading 0, a blip of the throttle dumps a load of fuel (acceleration enrichment) so the mixture goes rich (O2 = 1).

If your tuner couldn't explain this to you, find a new tuner.

[Marcus89]

There's a sticky thread at the top of this General Maintenance section - have a read!

At idle, it probably doesn't matter if the ecu is running closed or open loop - there probably isn't sufficient gas flow for the sensor to work correctly. It's likely set quite lean, hence reading 0, a blip of the throttle dumps a load of fuel (acceleration enrichment) so the mixture goes rich (O2 = 1).

If your tuner couldn't explain this to you, find a new tuner.

It's a nistune so factory ecu. Hmm so it would be normal for it to jump suddenly with just a blip of the throttle? He was saying that it was all over the place while he was tuning and so he has turned it off at current. I will read through it some more always good to learn

[Ben C34]

Im not too confident in your tuner, unless you have misunderstood him.

The o2 feedback has to be switched off when tuning a Nistune board, but then turned back on afterwards.

As the o2 sensor is a narrow band, it can only show when the car is at 14.7:1. When you blip the throttle it would go richer than this, so of course the sensor will show deviation from 14.7:1.

[Ben C34]

Have a read of the Nistune tuning guide on their site to understand more.

[Marcus89]

Cheers superben. Had a read of the o2 sensor nistune guide seems very simple. I think I may need to call him and try and verify what it was exactly doing wrong.

On a good note without the O2 sensor being used I am getting very good economy