Major MOT emissions failure!

[baz50]

Hi, this is my first post.

My renault clio 1.2 year 2000 failed quite spectacularly on emissions on it's MOT last week.

The figures are as follows:

1st test
CO - 10.415 (Max limit: 0.300)
HC - 7641 (Max Limit: 200)
Lambda - 0.548 (Min Limit: 0.970 Max Limit: 1.030)

2nd test
CO - 9.886
HC - 3693
Lambda - 0.669

It passed the natural idle test giving a CO reading of 0.027.

The guy at the testing centre was pretty sure this was down to the heating sensor so I replaced this and the oil, air and fuel filters, took it out for a good blast and it failed again.

I took it for a diagnostics test and was told that the engine and the engine management system aren't communicating with each other but they'd have to look further to tell me exactly what's wrong. That's the part I'm concerned about, how much looking further is going to cost.

Any ideas as to how to proceed would be greatly welcomed. Cheers

[stevieturbo]

for the tester to even make such a ridiculous suggestion shows how stupid he is.

Im amazed you arent also saying the car is running like a bag of ste and using loads of fuel

Because those numbers are beyond belief. Not only is it incredibly rich, but the fuel isnt getting burnt either.


I'd try it on a different exhaust gas analyser.

Edited by stevieturbo on Monday 1st February 21:12

[baz50]

It's running perfectly which is why I can't understand it!

Thanks for the suggestion, will look into that.

[Steve_D]

Can't help directly with your problem but would suggest you add some detail to your profile.

PH is full of petrolheads many of whom are in the trade so the next guy to read your post may be able to say "you're only down the road, pop in and I'll look at it for you".

Steve

[fatjon]

With those numbers it should be virtually undriveable, stink of unburnt fuel, be puthering sooty smoke and doing 5 gallons to the mile. Get it checked elsewhere. I smell a setup that will involve your wallet being emptied.

[baz50]

fatjon said:

With those numbers it should be virtually undriveable, stink of unburnt fuel, be puthering sooty smoke and doing 5 gallons to the mile. Get it checked elsewhere. I smell a setup that will involve your wallet being emptied.

Thanks for your response. It's crossed my mind to do exactly that. I think that may be the way forward, at least then I'll know for sure.

[TheEnd]

i have heard of people having mysterious problems, and it turned out the tester's probe was f-ed.

the engine not communicating with the ecu is a huge over simplification, i guess he's saying a sensor's live data feed isn't within expected limits, or missing, but he certainly hasn't given as much info as he could

[neiljohnson]

Odd ive never seen one fail so badly but pass the idle test on a clio i would be checking the throttle body, coolant temp sensor & the lambda. Sticking it on another machine to be sure wont hurt either.

[Martin Keene]

fatjon said:

With those numbers it should be virtually undriveable, stink of unburnt fuel, be puthering sooty smoke and doing 5 gallons to the mile. Get it checked elsewhere. I smell a setup that will involve your wallet being emptied.

+1

If it really was that bad, not only would all of the above be true, but there would also be an emissions failure warning light on the dashboard.

Word of caution, I bought a 2000 Honda Civic 1.8 VTi, 6 months later I took it for it's first MOT and it failed on emissions. It was still under warrenty, so I took it to Honda and surprise surprise it passed. Figuring Honda maybe didn't want to pay out on a car which was a few days away from being out of warrenty, I took it to another garage and paid a fiver for an emissions test machine. Passed that too.

Took it back to the test station and explained all this, and the onwer said, "Yeah sometimes they do that, you can leave them running all day at idle, but it doesn't get the cat to operating temperature. Take them for a run and their fine."

Cheers, thanks for that. Why didn't you do it then!

[baz50]

Thanks to everyone who has responded so far. I've had a few suggestions about the engine coolant sensor and have ordered a repaclement.

Just a quick question though, could a faulty MAPP sensor have something to do with it?

[CrashTD]

baz50 said:

Thanks to everyone who has responded so far. I've had a few suggestions about the engine coolant sensor and have ordered a replacement.

Just a quick question though, could a faulty MAPP sensor have something to do with it?

As in Manifold Absoute Pressure? Its is possible this is telling the ECU your car has too much air going in and its matching this reading with the equivalent fuel.

[stevieturbo]

baz50 said:

Thanks to everyone who has responded so far. I've had a few suggestions about the engine coolant sensor and have ordered a repaclement.

Just a quick question though, could a faulty MAPP sensor have something to do with it?

have you read any of the responses so far ???


Have you had it tested on a second machine ? instead of randomly running out and throwing money away with no sound reason for doing so ??

[Pumaracing]

stevieturbo said:

for the tester to even make such a ridiculous suggestion shows how stupid he is.

Im amazed you arent also saying the car is running like a bag of ste and using loads of fuel

Because those numbers are beyond belief. Not only is it incredibly rich, but the fuel isnt getting burnt either.


I'd try it on a different exhaust gas analyser.

Edited by stevieturbo on Monday 1st February 21:12

With mixtures that rich all the fuel can't get burned because there's insufficient air to do so. However I've never seen CO readings that high so I can't say what you'd expect the HC to be at such mixtures assuming no other engine faults such as poor compression, burned valves or defective ignition system.

CO can only be high because of rich mixture.

HC can be high in two circumstances. Rich mixture or unburned fuel due to ignition faults or physical engine problems preventing proper combustion.

It may just be a defective gauge at that garage. Getting an emissions test done at another garage would seem the best option before spending money on components that might not be faulty.

The diagnostics test you've had done which says the engine is not talking to the engine management system is rather bizarre because the engine doesn't talk to anything anyway. Engines IME are rather dumb objects which just react to conditions thrust on them and rarely speak. The engine management system only talks to itself and its own sensors. What the engine does meanwhile is none of its concern.

If it really is that rich then the possibilities include water temperature sensor, lambda sensor, fuel pressure and various other things which you don't really want to be replacing at random.