I've just had the car MOT's but it failed the Emmissions test as follows :

Fast Idle Test 2450-3050rpm CO: 1.51% (Limit 0.30%)

Second Fast Idle 2450-3050rpm CO: 5.95% (Limit 0.30%)

Natural Idle Test 750-1050rpm CO: 0.48% (Limit <0.50%)

Have you any clues as to what may be causing this.
I did perform an ECU reset last week and I didn't do the bit where the accelerator pedal is held half way down (as per posts on the BBS), would this of upset it.

Is it worth doing another reset or is it likely to be something else.

Many Thanks.....

 

Decat exhaust ?
Dirty Air Filter ?
Broken cat ?

 

Not de-catted (as far as I know)
New Airfilter
Cat Broken - your guess is as good as mine ?

If it is a duff cat, are there 2 and which one normally get replaced.

 

Knackered o2 sensor?

P.

 

What's an O2 sensor cost ?
Any way of checking it ?

I presume it's commonly known as a Lambda Sensor ?

 

Did you warm the car up before the MOT ?
May be a lazy cat, What year is the car?

Early cars are worst,need to rip-it for 15-20 mins before emission test, ie get the cat really hot.

Early cars had o2 sensor on the header pipes & are prone to failure. Usually get an engine check light if the sensor is dead & the ecu runs rich.

Had similar problems with my 94 WRX, any help, advice just ask & I try to help.

 

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by Scott.T:

Fast Idle Test 2450-3050rpm CO: 1.51% (Limit 0.30%)
Second Fast Idle 2450-3050rpm CO: 5.95% (Limit 0.30%)
Natural Idle Test 750-1050rpm CO: 0.48% (Limit &lt;0.50%)

<HR></BLOCKQUOTE>

Those figures seem to me to be <B>very</B> high if like you said have still got your cats in place!

We did a test last year (on a MY99) with a fully de-catted system and cold engine and got: 2,65% around 800 rpm and 3,01% around 2500 rpm. So check your sensors me thinks...

/G

(...again edited due to fast-fingers-on-keyboard)

[This message has been edited by Daemon_G (edited 01 August 2001).]

 

My MY96 failed emmisions test recently with about 1.5% at fast idle (can't remember the rest of the figures), one new air filter and a cleaned up lambda sensor later and it was back to well within spec.

Stuart

 

Been told by Subaru that it may be the lambda sensor, but to try cleaning it first, as are known to fail when dirty.

Shall be trying that later today.

 

Sounds like it could be a duff lambda sensor. Available from just about any auto shop (including Halfords). If you wanna get the genuine item, they can be quite dear, but at least it will have the right plug on the end.
Just FWIW, I achieved WITHOUT a cat figures well within the MoT spec, IIR about 0.16% CO and 120 ppm HC, the only problem being that my AFR wasn't the "expected" 14.7:1 hence not strictly a cat pass.... very weird... my emissions are BELOW spec, and yet it's still a fail (the cat is working perfectly, it's just ontop of a cupboard, not on the car)

Cheers,

Pat.

 

Was going to clean the Lambda sensor but didn't have a spanner big enough.

Anyway - cleaned the connections and done a ECU reset.
Emmissions are now 0.093%, so a bit better than the 5.95% seen on the MOT.

Will book the car back in for a retest, so hopefully it will be O.K this time.