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Discussion Starter #1
Bugger! After lovingly changing my 155's front suspension wishbones to ensure an MOT pass, the poor chap failed on emissions!

And, crikey, did it fail!!The CO reading was a staggering 5.38% vol, where the limit should be less than 0.30%! First culprit is the oxygen sensor (lambda sensor), but short of methodically changin everything until it works, I have no option but to get it checked on a diagnostic machine and rectified properly. So, I'm taking it in to WAD in Wolverhampton next week for a check and possible new sensor.

The only thing that makes me wonder is that last time the lambda sensor went, the car ran appalingly badly. This time it seems ok and I'm still getting pretty good economy.

Anybody any more ideas to throw in?
 
W

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They don't always cause bad running. Had my old Mazda 323F fail on the emissions and I couldn't tell anything was wrong with it. Lambda at fault, in fact that was my first encounter with the damn things!!

Had appalling affect on the twinny but not so much on the V6.

My vote sez lambda :D

wrinx
 

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Rich dont wanna put a downer on the situation :rolleyes: but i hope for your sake its not the CAT thats given up due to the old lambda sensor

That could be pricey
 

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Discussion Starter #4
The lambda was the first thing I suspected, then I thought about the cat... but the MOT tester said that the readings were too high for even before the cat, so it wasn't like the cat wasn't doing it's job. Also, I'm still getting pretty good economy, so I'm hoping that there hasn't been too much unburned fuel pumped through the cat, which is one of the main causes of feline death.
 
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I fail on MOT becouse blew silencer (second from the back) coused false emissions reading.I need to fix this, so can I simply bypass this section with flexible pipe (temporary)?
 

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Done your motronic test? (you know brake pedal 5 times) etc, WRINX help him out here (PS I have a new TPS on order)
 
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Oh yeah, forgot about that! With the key at "marcia", press the accelerator right to the floor 5 times in under 5 seconds and then look for the flashing injector light. I posted the codes recently.

I'm not convinced this gives the real problem though. Other faults can cause the lambda to show up.

Still worth a go tho wink

wrinx
 

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richward:
... but the MOT tester said that the readings were too high for even before the cat,
Am puzzled how did he measure the readings before the cat???????


Have you got the MOT printout and if so which readings were too high
 
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Err.... "Marcia"?

Who's Marcia?? And where is she and why should my key be with her?

How DO I do that Motronic test thing..... does it go for 8vs??

Would like to try though... i bet my instrument binnacle lights up like a christmas tree.

Cheers

Amir
 
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Doesn't work on cars without the "keycode". Seems to be 1995 cars on.

Turn the ignition to the first stop (marcia) when the lights come on. Then do the 5 pumps in under five seconds. Look at the binnacle to see if anything happens...good luck :D

wrinx
 
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I think minr originally came with the keycode..... at least that's what the garage guy said that mess of wires hanging from my dashboard was all about. Only its been obviously removed.

Will try it anyway- I'm sure Marcia won't mine- and tell you the results

Amir
 
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When the Lambda was at fault on my V6, the injector light came on and off based on throttle position. Cruising it came on, hard acceleration and deceleration it went off. You can test the Lamda using an electrical tester, it gives a voltage reading that varies depending on trottle etc. If you get the same voltage reading all the time then its not working as it should fluctuate up and down between 0.1 and 1 volt (I think...). I tested mine before replacing it.

The V6 lambda was £55 from Mangoletsi, it is easy to fit. The V6 CO with duff lambda was 4.8%.

I've just MOT'd the 16v and that wouldn't pass at 2500 rpm (0.8%), we had to take it up to 3500 rpm and after about a minute it dropped to 0.18%.
 

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Weird - my decatted 75 3.0 litre is 0.5% and everything else within limits - the only reason they let me off is because there is nothing else wrong with the car
 
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H'm

Well I tried the motronic thing..... key at marcia and five quick pumps of the accelerator......

Nothing happened on the dashboard but the stereo came on!

I'm a worried man now.

Cheers

Amir

eek!
 
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Reg

I think the emission depends on the year of car, 1994 I think is the cut off (jimybob will know..), therefore the reading on your 75 is fine even though its decatted, as the law didn't dictate it had to have a cat when made, and I think it is allowed to have a plus variance. Next time you're at the MOT station look at that poster on the wall that states emissions. My mate has done the same on his MR2 turbo, which is a 93 L reg and he has never had an MOT issue.
 

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The departmnet of transport reckon cars registered after July 92 (in otherwards August) require a CAT test but there some exceptions, like the Metro. The more "advanced" MOT stations enter the chassis and engine number (this is the important one) and it comes up with a CAT test!
The first question I always ask garages is "does it require a CAT" test? If they say yes I walk away.
 
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there is a cut off date and like reg said there are some exeptions.generaly though k reg on need a cat test with the limits between 0.50 and 0.30 depending on make and model.

you need to make sure your car has a blumming good thrashing before you get to the test station and try not let it tick over for too long also make sure the emmision test is done as soon as you get there,if not the cat will cool to much or if its left ticking over the cat will over heat..4000 rpm for a good 2 minutes will sort out most problems.
 

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Discussion Starter #18
Turns out it was the lambda sensor... but while it was in I had a 72k service and the belts and tensioners changed. It's only been about 35k since they were last done, but I'm feeling very lucky now - all three tensioners were shot - two of them were very noisy with the bearings sounding like they were about to fall out and the cambelt tensioner, even though it was a newer 'white' type, was well worn. All in, it cost me a gnats chuff over £500, but I reckon it wsa money well spent... it's running a lot better and the engine is so much quieter!!

SF - the MOT tester didn't test the emissions before the cat - he said that even without a cat, the readings shouldn't be that high - i.e., the cat doesn't remove that much anyway. But, lambda it was, and the CO reading is down from 5.38% to 0.25%. I should recoup some of the above bill on reduced fuel costs!
 
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