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[Tezray]

This is for my Hyundai before anyone asks, but i just have a couple of general questions....The hyundai failed the mot on high emission (it was reading about 5.2 when it should have been reading between 0.3 and 0.2   Something like that anyway). So my question is what could be causing such excessive readings? Cat? Lambda sensor? Both? Headgasket?!

I've chucked in some Wynn's 'stop smoke' because i have noticed it does use a little bit of oil, but there's no oil in the water and it doesn't appear to smoke. I have noticed that if i open it up or load the engine i can smell the cat, i guess this means it's probable nackered. Today, i also tried disconnecting the lamdba to see how it ran and it didn't change a thing. With it disconnected would it run lean? I smelt the exhaust gases with it connected and disconnected and in my opinion it smells a bit 'petroly'.

Basically if i need to replace the cat and lambda i'll probably just sell it with no MOT. Is it possible that the HG is failing? It runs perfectly though and doesn't use water, just a small amount of oil and there's no oil mixing with the water. Any idea's?

[Marks DTM Calib]

Blimey Tezray, your going off at a tangent arn't you!

Your emissions are high, not your hydrocarbons so its not using much oil (not enough to fail)

Is it getting to the correct operating temperature and the is the ECU water temp sensor working as it sounds like its not going into closed loop control (hence the lambda is doing nowt).

Is the fault light on?

[Tezray]

No fault lights on and i think it's getting to running temperature...just below half way on the gauge? Not sure if the water temp. sensor is working, how can i test it? I've got a multi meter but haven't got a clue what to do with it  

Here's the results;

1st fast idle test

CO: < 0.3% Vol
Reading 4.44% Vol

HC: <200ppm vol
Reading 441ppm vol

Lambda: 0.9-1.1
Reading 0.883

2nd fast idle test

CO: < 0.3% Vol
Reading 5.38% Vol

HC: <200ppm vol
Reading 546ppm vol

Lambda: 0.9-1.1
Reading 0.849

Natural idle test

CO: 0.60% vol
Reading 3.48% vol


NOT GOOD!!

[omegaV6CD]

No fault lights on and i think it's getting to running temperature...just below half way on the gauge? Not sure if the water temp. sensor is working, how can i test it? I've got a multi meter but haven't got a clue what to do with it  

Here's the results;

1st fast idle test

CO: < 0.3% Vol
Reading 4.44% Vol

HC: <200ppm vol
Reading 441ppm vol

Lambda: 0.9-1.1
Reading 0.883

2nd fast idle test

CO: < 0.3% Vol
Reading 5.38% Vol

HC: <200ppm vol
Reading 546ppm vol

Lambda: 0.9-1.1
Reading 0.849

Natural idle test

CO: 0.60% vol
Reading 3.48% vol


NOT GOOD!!

You need to monitor the rsistance of the sensor it will either change with temperature change or it will not which will mean that youneed a new sensor.

[Tezray]

Is it possible to short the sensor so that it goes into constant closed loop control?

I've found the 2 ecu controlled water temp sensors and i've cleaned the contacts as they didn't look great....

[Marks DTM Calib]

Cant realy say as we dont know what they should be....probably going to be a few Kohm when at temp.

Its clearly not going into closed loop mode, you can tell that from the lambda values.

So the engine temp is getting to 90degC according to the temp gauge.....and the stat isnt stuck open?

[Taxi_Driver]

Ive had 3 cars where the thermostat has got stuck open and always noticed the same.
Norm operating temp (90ish) takes ages to get there and only usually when driving in traffic or letting it idle for ages.
When it is up to temp, take it for a run on a bit of open road and the temp drops down to 80ish or lower, lower than it should.

If its doing this then as Mark says thermostat is duff.