VR6 MOT CO emissions fail - any ideas?

[was8v]

The initial message has been deleted from this topic.

[mmm-five]

Is it used for lots of mileage, or just town driving?

How many miles has it got on it?

Is it the original exhaust & car?

Do you have it regularly serviced?

Does it use/burn any oil?

Have you put any of those 'magic' engine treatments in?

[ringram]

Check your plugs for nice clean burn, are they oily etc?

CO is incomplete combustion, so look at a clean spark and timing too.

Oil through your PCV can mess with a clean burn so see if you have oil in your intake, maybe it could do with a catch can?

Finally if you have done heaps of miles maybe a new Cat will help clean Oxidise the CO?

Edited by ringram on Friday 16th January 12:11

[gti-ted]

I would
Change the oil and air filter + plugs
Remove lamba sensor and clean with brake cleaner and the Airflow meter

Give the car an absoulte thrashing before it's retest ( It works trust me )

A combination of all of these should see a pass unless as stated by someone else your cats goofed

Ted

Edited by gti-ted on Friday 16th January 12:14

[stevesingo]

I would try a new Lambda sensor, a full tank of juice and a good thrashing. It is normal for lambda value to fluctuate, a new sensor may reduce the dead zone.

Other than that the Cat would be next.

Steve

[rsstman]

fuel treatment thingys seem to get our cars to pass on emissions.

[Ladvr6]

Would agree with what has been said above. Normally on a vr if its running rich the first thing to change would be the lambda. The first sign of this needing changing is black smoke out the back on throttle. if you are going to the hassle (it'll be a case of 2 mins or 2 hours!)of taking it out to clean, you might as well replace with a new one. next would check the afm as this are known for failing.

[rsstman]

was8v said:

rsstman said:

fuel treatment thingys seem to get our cars to pass on emissions.

Any particular make? Did they pass after a borderline fail?

yes indeed, i think they were wynns treatments. worked in an e320 and a ford galaxy. the local garage did them.

[ridds]

Wouldn't think it's the Lambda sensor, HC's are very low and not running hugely rich.

If the Lambda was on the way out it's likely to default rich which would send these out.

Last time I saw results like that it was a cat that had failed, although I wouldn't believe it at the time.

Check for any air leaks on the inlet side, and that the filter is clean. I'd suggest getting the Cat stinking hot too by running high engine speeds and loads and then letting off the throttle and leaving the engine to rev with the movement of the car.