Astra 1.4 EcoTec running rich

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Astra 1.4 EcoTec running rich

Postby stevie69p » Thu Mar 07, 2013 12:03 pm

Hi,

first time poster here... we recently got a Picoscope 4 channel kit and I have been trying to get to grips with it...

We have a Vauxhall Astra 1.4 EcoTec 2002 model in the workshop with high CO.

readings are CO 0.8, HC 130, o2 1.8%, Lambda 1.02

No DTCs present on vehicle. No misfire, car runs ok....

If I pull the EVAP return hose off the throttle body to introduce unmetered air into the inlet manifold, the engine speed increases to around 2500 and the emissions readings come down to where they should be. CO 0.2, HC 35, o2 0.4%, lambda 1.01 ish. Fuel rail pressure seems good at 55 psi. I've scoped the no. 1 lambda sensor and its switching merrily between 0.1 and 0.9v.

Anyone have a direction to go?
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Re: Astra 1.4 EcoTec running rich

Postby Liteace » Thu Mar 07, 2013 1:52 pm

when's it switching merrily between 0.1 and 0.9v, before or after you pull hose off. Whats B1S2 upto ? any captures ?
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Re: Astra 1.4 EcoTec running rich

Postby stevie69p » Thu Mar 07, 2013 3:32 pm

Liteace wrote:when's it switching merrily between 0.1 and 0.9v, before or after you pull hose off. Whats B1S2 upto ? any captures ?


Before the hose is pulled off (i.e. the normal set up). B1S2 is switching too, between 0.2v and 0.6v ish IIRC. I didn't scope it, but was watching it via live data during my initial run through of the data available. Sorry, I didnt take any captures; the only thing I would say is that the trace looked a bit noisy but I discounted that as being an issue as the switching frequency and voltages looked ok.

My train of though was that since the engine is capable of running at normal emmisions levels when the unmetered air is added, that either the injector time is too long (being influence by some other factor) or that we have a leaking injector?

I should point out that I'm very new to both scopes and diagnostics in general, so am really looking to try and get some hands on experience where I can do.

Thanks.
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Re: Astra 1.4 EcoTec running rich

Postby arjen » Thu Mar 07, 2013 6:12 pm

Hello,

You have to replace the katalysator. The switching of the first lambda indicates a closed loop, witch is good.
Switching of the second lambda means the katalysator is not functioning. Thats also the reason that there is some hc and o2 left.

Most times this wil set a fault code (p0420). But it can take a while before the code shows up again after clearing the fault memory.
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Re: Astra 1.4 EcoTec running rich

Postby Neilcur » Thu Mar 07, 2013 6:44 pm

Hi,

What arjen is sayin is correct it will need a catalyst going by what you are sayin. If i were you i'd scope both sensor signal wires and see what bank 2 is doing as live data won't refresh as fast as the scope can capture. The bank 2 sensor should be a straight line which indicates the cat is doing it's job but if it is switching like s1 which is probably the case this indicates that the cat isn't dealing with the gasses properly and causing s2 to switch. Just a quick check that proves if thats the case or you could just change cat with no testing its up to you.

Thanks Neil
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Re: Astra 1.4 EcoTec running rich

Postby Robski » Thu Mar 07, 2013 7:09 pm

You have to replace the katalysator. The switching of the first lambda indicates a closed loop, witch is good.
Switching of the second lambda means the katalysator is not functioning

Who says it was 'lit' ?

The bank 2 sensor should be a straight line which indicates the cat is doing it's job

Yes if the Cat is 'lit' !

A few tests are available to nail a Cat :wink:
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Re: Astra 1.4 EcoTec running rich

Postby Neilcur » Thu Mar 07, 2013 7:22 pm

I take it when you say 'lit' you mean normal operating temperature?

What other checks can be done? Be interesting to know!
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Re: Astra 1.4 EcoTec running rich

Postby stevie69p » Thu Mar 07, 2013 7:37 pm

Thanks for the replies folks. I did have a thought that the cat might be goosed, having seen cars before that were just failing CO at say 0.5 and slightly elevated HC levels. It was just that this one was slightly higher again at 0.8 that was putting me off blaming the cat, but now that I cast my mind back to the diagnostics training course I went , I can remember that B1S2 should have been a steady voltage, not fluctuating. Just sometimes with no one else in the garage to ask for a 2nd opinion, you start to doubt yourself...
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Re: Astra 1.4 EcoTec running rich

Postby Liteace » Thu Mar 07, 2013 9:21 pm

Lucky you can remember your diagnostics training course, I cant even remember me own name sometimes, Im still learning even now, every night reading a bit more to keep up with these vehilces that get more and more unnecessary shite on them, training DVD's & books juts keep eating away at profit as they're not cheap, when you think you know 90% of it something new will challenge you so then its another large chunk gone to buy the next lot & I dont think it'll end the way technology is advancing in the automotive industry, sometimes it just dont make sense, what we have to pay out and what we get back, it would be cheaper and less stress to get a job on the bin lorry
Anyway rant over :D Its good that you remembered what you got taught now you can move on to the next step and get this vehicle sorted, paid and out ready for the next one
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Re: Astra 1.4 EcoTec running rich

Postby antthecat » Fri Mar 08, 2013 5:27 pm

What are the fuel trims at idle and at 2500rpm, if stft and ltft ate within +/-10% with everything connected then it should be safe to fit a cat.
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