My 93 import Z32 N/A auto, sold it earlier this year to a lad down the road.

He rung me today saying it's failed the MOT on emmisions? I had it through 3 MOT's and never had a problem? It's completely stock except air intake and in very good low mileage mech condition.

He said the MOT chap said it was worse on idle than mid revs? he's going to bring it round in the morning so I can plug the laptop in for a look.

Any suggestions on what might be the cause before I take a look will be greatfully received :D

O2 sensors mate

Cheers Nick, He popped round this morning and we had a quick play around.

looks like the left hand 02 sensor has gone. Did a comparison with my zed and both my 02 readings are almost identical at idle and flick up and down nicely when you blip the throttle.

On his car the right hand 02 was giving results similar to mine but the left hand completely different, sometimes zero and then a reading? checked the connectors and were clean like new.

 

All other readings looked normal and had a good look under bonnet but could see no obvious problems.

 

Tried the trick with pulling the vac line of the balance bar, he popped back round the garage for them to re-check. They tried the probe up both tailpipes and they said it was worse?

 

So does a failure of either 02 sensor cause a default increase in fuelling on all cylinders? Anyone?

Tried the trick with pulling the vac line of the balance bar, he popped back round the garage for them to re-check. They tried the probe up both tailpipes and they said it was worse?

 

Bit of an update, The Mot guy was a bit busy in the morning and told him to bring it back in the Afternoon and He would have a look at it.

 

He took it back in the afternoon with the Vac line still disconnected and the emissions had come right down in spec and it passed :dance::nana2::dance: