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Discussion Starter #1
Hi there,

I'm having a bit of trouble getting my MY2003 Corsa with the Z12XE engine through MOT (Swedish) due to high emission values. The values I got are:

CO at idle: 0.4 (limit 0.3)
HC at idle: 45 (limit 200)
CO at 2500 rpm: 0.5 (limit 0.2)
Lambda: 0.98 (limit 0.97-1.03)

I've recently replaced valve seals. The compression is good 13.2,13.1,13.0,13.2 (bar). Oil and filters are new. Spark plugs are new.

There are no fault codes, checked with OP-COM. However, when I check live values Air/Fuel Ratio is set to Lean which I find strange, high emissions should give Rich (I think..).

Are there any common issues with theese engines? Like sensors? If the sensor is bad but not so bad that it sets a fault code.

How is the catalytic converter quality? My car has 210 000 km (130 487 miles).

All help appreciated!
 

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High CO suggests incomplete combustion (as you say, lean suggests plenty of oxygen to fuel so you'd expect CO to be fine). It's not very scientific, but I also failed on my emissions (unlike England, workshop garages in Spain do not usually have emissions testers) which I was not expecting. I had driven 30 minutes at mostly 80-100km/h to the testing station. Even so, because I had used the car mostly for short, low-speed journeys previously, my garage suggested I put some injector cleaner additive in the petrol tank and drive around a lot in low gear, keeping the revs high.

It's not the way I like to drive but I stayed in 3rd or even 2nd a lot for a few days then went for a retest (driving there in 3rd at 100km/h) which the car passed easily.
 

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According Bosch, their oxygen sensors work up to 160.000 km, after that they are junk. You’re 50.000 km past that, when was last time you changed both oxygen sensors and with which brand?
 

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Give the car a good thrashing, 5000 rpm minimum for each gear change and keep the revs as high as you can, make the cooling fan kick in then get it straight in for an emissions check (if they're then low enough ask the inspector to pass the car). If this doesn't get a pass I'd look at replacing the oxygen (o2) sensors in the exhaust.

Here in the UK most mot inspectors dont connect the RPM feed of the machine to the car, thus meaning we can raise the idle speed to try and gain a pass value.
 

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Discussion Starter #5
I recently bought this car so I can't tell when/if the O2-sensors are replaced. By the look of the first one, I don't think they're ever replaced. I'll try the "run like hell with injector cleaner" approach for some days first and get a new emission check after that. Before I bought the car, it had been standing still for almost 2 years. Maybe, all it needs is some hard love :cool:
 

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Yes, that sounds like the first, almost free, thing to do. In Spain, my Modus 1.4 petrol had spent the winter only used for shopping trips then most of the summer not used hardly at all while I did all the long drives in my diesel Combo. I took it for a July ITV test and it failed (despite a quite long drive to the test station). After the Exploits on Viagra driving, it passed. I returned to the UK in November to my petrol Focus and, just to be safe, did the same thing before its MOT which also passed. If not, then you can consider the O2 sensor route.
 

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Bad maintenance with previous owner, bad maintenance with the new one. I think governments should get tougher with the laws.
 

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I know what you mean, Liviu. But, I had the garage fully service the Modus (oil, all filters and sparks), check everything before its ITV and I was surprised it failed on emissions, almost as surprised that the garage told me to pour some injector cleaner in and blat the engine - it'll be fine. It worked (as in it passed) but made me think "surely after another layoff and short shopping trips, it'll be back to high emissions?" but, apart from unnecessary long journeys in low gear every so often, I don't have an obvious answer. The car (like my Focus in the UK) has a full service every year when it has driven less than 10k kms. I don't think it's necessarily parts failure, just a consequence of the layoff.
 

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Discussion Starter #10
Today I took the car on a "run like hell drive", high revs for a long time, with some additive (injector cleaner). After a while, it started hesitate, the idle became rough and suddenly the MIL lit up. Which is good, at this point. A P0335 - Crankshaft Position Sensor "A" Circuit Malfunction. I know BMW's can get high emissions due to faulty crank sensor, I hope it's the same with a Corsa.

What do you think?
 

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Discussion Starter #13
Finally got it through Mot but it was on the verge. A tiny bit below the max value for co2 at 2500 rpm. The other values where good. It seems like it is geting better the more I drive it. It probably need to get in shape again after two years rest.

I've changed the crank sensor, it might have helped a bit.

Thank you for good input here!
 

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Glad to hear of your pass (y) . I'm sure that with good fuel, more runs and keeping up with checks and maintenance it will probably improve its numbers.
 

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Discussion Starter #18
So was it the crank sensor?

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Not sure. It seemed the more I drive it the better it gets. It had been standing still for almost two years so it might have needed some "coming back to life"-driving.
 
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