MOT Failure

[Homer-Simpson]

My car has gone in for a MOT (first one since I purchased it). The decat was removed and the old cat put back on and it has still failed its emissions test.

Anyone got any advice? The garage are saying they cannot check anything as they don't have any diagnostic equipment. What should I do now :S Anyone know of a place in the West Midlands that might be able to help?

 

[gtruk]

If its not been used in a while you would be best leaving it on for a day or so and giving it some abuse. Or better yet take it out for a thrashing to get the cat hot then get ur emmisions done. Should pass then

 

[geesus69]

did you take it for a decent drive before mot'ing it? cat's work better when warm

is the exhaust blowing at all? this can cause a poor emissions reading

how much did it fail by?

edit: beaten to it lol

 

[Craig]

could be the lambda sensor mine failed because of that

 

[Mark One]

^^ as above get the cat warm. If that fails (and it might) you need a new lambda sensor.

 

[Homer-Simpson]

Idle figure was 1.15 on the test
Fast idle was 1.56



Looks like there is a big issue somewhere! I have been quoted £125+VAT for a new CAT. Not too sure what to do as I have been getting low MPG which could be the lambda sensor I suppose?

 

[Mark One]

Yes, read the link i put in above. Your lambda has gone

 

[Fastchip]

You have a RST right ? So why dont you use it to check your lamda sensor.
Might save you some $$.

 

[Homer-Simpson]

Indeed I do! How would I check it though? The only faults it brings up on the front screen are the ones I posted in the previous thread (http://www.casa-canya.co.uk/rstuner.jpg). Should I be checking the live data?

EDIT: I have just checked the manual and I take it I run an actuator test?

 

[gtruk]

No an actuator test would be solenoids etc... lamda reading would be under live data i assume

 

[Homer-Simpson]

So what sort of figures are acceptable? I suppose I should pick up my car and take a look tonight!

 

[gtruk]

to be honest id be interested to find out too, and what reading it is we are looking for.

 

[Homer-Simpson]

Just had a phone call from the MOT centre. Every other car that came in today failed for the same reason. Their emissions machine was faulty. They have tested it at another site and it has passed!

The worrying thing is they were saying it took 2 hours for them to remove the decat (they don't want to put it back on as they said it will take another 2 hours to do it) :S

 

[Goders172]

its not an easy job mate, its a b*tch to get on/off

 

[Fastchip]

to be honest id be interested to find out too, and what reading it is we are looking for.

The Front O2 lambda sensor should alternate between 0.1 V (lean) and 0.8 V (rich) every 0.5 - 1 second at idle, warm engine.
When the sensor ages ususally it cannot reach more than 0.5-0,6 V anymore.
More recent ECU's have a 'lambda sensor aging ' parameter.

 

[gtruk]

thanks henk

 

[Homer-Simpson]

to be honest id be interested to find out too, and what reading it is we are looking for.

The Front O2 lambda sensor should alternate between 0.1 V (lean) and 0.8 V (rich) every 0.5 - 1 second at idle, warm engine.
When the sensor ages ususally it cannot reach more than 0.5-0,6 V anymore.
More recent ECU's have a 'lambda sensor aging ' parameter.

Thanks