Jimny VVT less power at low revs than non-VVT?

Ignore everything I just wrote, I only saw the red trace which looks normal for sensor 1. Sensor 2 looks like it has gone full scale and looks like a sensor or connection fault.

Try a little throttle or blipping the throttle, does it ever change? If not it’s a connection or sensor fault. I would also expect you will get an OBD fault code for this.

Robin

Thanks, Robin

There is no fault on the OBD... I'll try a little throttle tomorrow morning. If it doesn't change then I could try replacing the second O2 sensor after the cat?

Would a failed O2 sensor after the cat cause any performance issues? Or only the sensor before the cat?

tomlil01 wrote:

Thanks, Robin

There is no fault on the OBD... I'll try a little throttle tomorrow morning. If it doesn't change then I could try replacing the second O2 sensor after the cat?

Would a failed O2 sensor after the cat cause any performance issues? Or only the sensor before the cat?
 

Usually no. It just puts the EML on with an emissions fault because it can't monitor the cataylst.

I could be wrong and it goes into limp mode, but certainly other makes that I am familiar with don't.

It should be around 0.9V indicating no oxygen, so it is out of range.
 

I think the 1.2v was a red herring. After warming up the car with a drive it was about 0.8 on sensor 2 at idle, and crept up slowly to 0.95 after 5 or 10 minutes of idling.

Driving with the engine under load it was about 0.85/0.9, and dropped down to near zero when taking my foot off the throttle.

Is this a sign that the cat is gone? I have replaced the back (1 year ago), but not the front.

Is the front easy to change so you know?
Thanks
Lee

The steady 0.9V means the cat is working.

Whether the cat works or not doesn't affect how the engine runs. What we've been telling you is that a partially blocked catalyst will restrict the engine power because the exhaust can't get out fast enough and back pressure builds up.

What tends to happen is the front catalyst blocks and starts to break up and crumble, then the dust & fragments lodge in the rear catalyst blocking it.

Other members have simply had the broom stale to the front catalyst and rodded it out to an empty pipe, then run with just the rear catalyst and it still passes emissions at MOT.

I think the front catalyst is part of the manifold, easy enough to change, but spectacularly expensive!

0.9v means it's working? My understanding was that it was that it should about 0.45v on the 2nd cat.