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scottambrose
Wednesday 29th July 2009, 13:52
someone has removed the internals of my cat on my 2.0t but as it has 2 lambas its making it run very rich. as the post cat is sensing the same amount of emissions as the pre cat. can i fool it in anyway to think its still there. im tight and dont want to buy a new cat.

p fandango
Wednesday 29th July 2009, 14:04
you can buy a spacer ring to move the 2nd lamba out of the air stream so it reads the lower emission levels that way & keeps the ECU happy, i've no idea where to get one from tho, sorry

Wombatbomb
Wednesday 29th July 2009, 14:36
Alternatively, some tuners (MTE for certain) can alter the cars map so that a default value is fed to the ECU rather than the actual reading from the sensor.

p fandango
Wednesday 29th July 2009, 14:47
Alternatively, some tuners (MTE for certain) can alter the cars map so that a default value is fed to the ECU rather than the actual reading from the sensor.
that would work out dearer than putting the cat back in

Dangerous Dave
Wednesday 29th July 2009, 15:18
If you're good at DIY you could fabricate a spacer ring like PF says.

scottambrose
Wednesday 29th July 2009, 16:59
could i unplug the sensor from the exhaust n blank the hole off and then just leave the sensor plugged in under the car.

Dangerous Dave
Wednesday 29th July 2009, 17:08
You could, but then that would have the opposite effect I guess. You could try it, theres no harm in trying.

p fandango
Wednesday 29th July 2009, 17:47
if you unplug it the ECU will know the circuit isn't complete & throw a 2nd lamba missing/signal absent fault instead

Wombatbomb
Wednesday 29th July 2009, 18:51
You could, but then that would have the opposite effect I guess. You could try it, theres no harm in trying.

Just taking the sensor out of the exhaust doesn't work, from the way I understand it the ECU is a bit too clever. It expects there to be some emissions detected at the second O2 sensor, if it detects none at all it thinks the sensor is broken and throws a CEL.

nobananas
Wednesday 29th July 2009, 22:22
Hmm, interesting. All the vehicles I've worked on the post Lambda sensor doesn't affect the fueling. All it has done is triggered a MIL with a 'catalytic converter outside of limit threshold' fault code or similar. I'd then do an emission test to determine whether there is a cat fault or whether the fault is with the pre or post Lambda. I guess Volvos must use the post cat sensor as a necessary input then, will have to watch that if I get an Ovlov in with those sort of issues then.

scottambrose
Monday 3rd August 2009, 10:43
the front lamba reads between 1 and 3 volts as does the rear lamba sensor.

is it likely to be causing damage to the car running like this. it drives fine just got the eml on. i checked the pre lamba and its coloured white. would this mean running lean. as the tailpipe is very black indicaring rich running?