V6 MOT Failure Emissions

[cheffy34]

My firsy reaction would be lambda the test should have shown that i had my emmisions done tuther day flip to help nail my probs, says the same i'm goin lambda, i'm really lookin at a universal part for £45 as apose to the mazda at £145 so as you can imagine it fav at mo, but will have to be spliced onto the the mazda plug easy peasy , i've done shed loads of reading on it flip your lambda is pre cat a bitch to get out and a pain in the arse i've had em fail on a few of my cars now, but it was apole that put me onto the uni part think he may have had his done. goodluck wiv it stud



Dar

[scanner]

When the missus old Fiesta failed the MOT on it`s emissions - the lambda was at fault - the tester said to remove the sensor and clean it with brake cleaner as when cars do low annual mileage the sensor gets clogged up with soot - cleaned it up and replaced it and sent it in for a retest and it passed. Just a little tip - dont clean the sensor on a nice clean concrete path - it took about a year for the stain to fade.

That was the trouble with B-i-L's car, it was a cabriolet they only used in the summer and wasn't used hard enough to keep the sensor clean.

[cheffy34]

Generaly if the sensor gets sooted up badly it a sign of bad mixture i thought hard brown layer oil contamination i think

[Mazman]

Just look the tester in the eye and inform him u are going to use a donor car for the emissions test .
If he doesn't look scared put £20 in his hand.

[cheffy34]

How does it run flip is it holding back on ya

Dar

[flippa]

tis running great cheff , im using it as an everyday get to work so the under-used bit dosnt apply....maybe its summat to do with the thrashing its got this last year ...so i guess its due a little tlc anyhow

[cheffy34]

tis running great cheff , im using it as an everyday get to work so the under-used bit dosnt apply....maybe its summat to do with the thrashing its got this last year ...so i guess its due a little tlc anyhow

Yip great perol prices are down

[scanner]

tis running great cheff , im using it as an everyday get to work so the under-used bit dosnt apply....maybe its summat to do with the thrashing its got this last year ...so i guess its due a little tlc anyhow

It could just be a crap lambda sensor - they appear to be a very touchy component - I'd just get a new one fitted, I don't think they are horrendously expensive.

http://en.wikipedia.org/wiki/Oxygen_sensor

http://www.autodiagnos.com/fileadmin/as ... ensors.pdf

http://www.lambdapower.co.uk/

Looks like about £20 or so if you're lucky.

[apole]

Hi Flippa,

Number of things it could be.

Check your air filter, or even just take it out for the MOT.

The lambda sensor tends to fail after 50-60k and as it does so progressively the readings it gives the ECU makes it run progressively richer. BTW you can test these. The sensor can be reached either under the sliding door side or from under the passenger seat. It looks a little like a spark plug, 2 wires in the top of the exhaust just before the cat.

http://rover800.gaima.co.uk/Rover800/ww ... g%20Lambda


Using a digital multimeter on volts, earth the negative lead, then find which one of the 2 wires gives a reading. With the engine fully warm you should get a reading jumping around between 0.1 volts and 0.9volts. Below 0.4 is lean, above is rich. It should be moving around all the time though.

To replace you get an 18mm univeral 2 wire lamba, google and there is a company called just lambda's or something similar, they are okay.

Next thing I'd check is the MAF, you'll see that inbetween the airbox and engine under the drivers seat. I'd check the multiplug, remove and clean the contacts. I have yet to get round to removing mine and cleaning with electrical cleaner. The MAF measures how much air is going into the engine. done so by a heated wire, something to do with how much is needs to be heated equates to airflow. Anyway these can gunge up and then give false readings.



Is the rest of the engine in good order, oil, spark plugs etc?

Make sure the engine is hot when it goes for the test btw, tester should make sure of that.

Good luck and keep us posted.

[The Great Pretender]

Sorry to hear about your problem Flippa. If it isn't the O2 sensor, maybe it could be the air or water temp sensor failed. Common sense (remember that) would make me think that when a sensor fails, it fails safe so the ECU adds fuel. My understanding is when cold the engine runs in open mode (closed loop to keep fueling at 14.7 when hot) so one of those sensors may be causing the rich reading.

Good luck Mate.

[bigdaddycain]

It sounds like a self perpetuating issue too, the sensor starts to fail, it's over fuelled, then the sensor gets more clogged... it might be an idea to change the spark plugs too kieran... Hope ya get sorted.

[flippa]

thanks for the advice guys , have got the parts on order including new spark plugs , i cleaned the( maf) apole mentioned , have the lambda on order , changed the oil with a new filter today just for good measure....so just waiting for the parts and illl get it in ...thanks again for the invaluable advice

[bigdaddycain]

Hope it sorts it kieran... Forgot to ask earlier, are you happy with the amount of oil the engine gets through? Do you have to top it up much?

[flippa]

funny you say that BDC... since i changed it last year, i have not checked the oil since just changed it again on sunday with a new filter and was happy with the amount that came out , i will keep a closer eye on the levels

[srs41]

The readings you had would suggest a faulty cat (catalytic convertor) , lambda readings should be between .97-1.03 , sometimes the cat becomes lazy & requires a good heating to get it to kick into life , but if they tried everything at the test as I would do ( I MOT for a living )then it may be you cat has used all of its lives , so if your lambda reading was between .97 & 1.03 & hc reading was below 200ppm then you may be looking at a dead cat .Sorry to be the bearer of bad news .