fooling the obd with no cat

[scottambrose]

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]

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]

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]

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]

If you're good at DIY you could fabricate a spacer ring like PF says.

[scottambrose]

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]

You could, but then that would have the opposite effect I guess. You could try it, theres no harm in trying.

[p fandango]

if you unplug it the ECU will know the circuit isn't complete & throw a 2nd lamba missing/signal absent fault instead

[Wombatbomb]

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]

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]

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?