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Hi CO-2 emmisons on VX Carlton - Why and can it be adjusted ??

Dear all,

My dads Carlton Diplomat 2.0i Auto (J plate) has 'Just' passsed MOT, but the CO-2 emmissions are high.

The reading was 3.44. The limit I understand is 3.50 and worryingly they have generally been around half this at all other MOTs.

Can the CO-2 be adjusted ??, or what perhaps is causing the high reading and is it something to worry about.

We did have a drama (Smoke from Alternator post the other week) when he connected the battery the wrong way around, but first impressions implies everything appears to be working OK. We did however have to reset ECU (Diconnect battery for a while ?) as ABS light occasionally came on !!! - Not come on now.

I wonder however if connecting the battery the wrong way around has done something to the ECU if this is the thing which controls the emmisions ???

Any comments / ideas as to why Co-2 is high and perhaps how can be adjusted ?? Also, with high Co-2, is there a more serious problem approaching ???

Thanks in advance.

Andy.

Reply to
Andy Smith
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First, I think you mean CO (carbon monoxide) rather than CO2 (carbon dioxide, which is not measured as part of the test)

It is possible to adjust the CO on this age of Carlton, as long as the vehicle in question is not fitted with a cat or O2 sensor (doubtful if the CO has managed to get that high). On the air flow meter, which is mounted on top of the air filter box, there is a round blanking plug to the side of the electrical connector. Under this blank is a small multi-turn potentiometer which can be used to adjust the idle mixture.

It would be best first of all to examine all other avenues that could lead to a high CO, such as incorrect fuel pressure (faulty pressure regulator), faulty coolant temp sensor etc. Once this has been proven OK, then an adjustment can be made. Typical values for the CO for this engine lie in the range of 0.5 - 1%. If the screw is moved too far either way from its nominal centre position, then it will cause the EM light to illuminate and store a fault code in the ECU.

HTH

Anthony Remove eight from email to reply.

Reply to
Anthony Britt

I believe that this model does NOT have a Cat (last ones before they started to fit them), not sure if this is good or bad ? but not sure about the 02 sensor - where is it ? (nothing on exhaust- not sure from memory on manufold

I have been told that gloggy injectors can cause high emmisions ???, and often good to run a bottle of injector cleaner through and give the car a good run.

I suspect the reading was not done right, as the person doing it was a

17 year old grease monkey who was busy talking to his mate rather than checking waht he was doing !! I would have thought that a false reading would be low ??

Not to worry I think, I'll run the injector cleaner through and see what the numbers are next MOT !

Thanks,

Andy.

Reply to
Andy Smith

I doubt injector cleaner would make any difference. More likely one of the following:

- dirty air filter

- blocked breather hoses, particularly the small one which goes to a stub on the intake manifold. This stub usually blocks with gunge which then turns into fairly solid carbon. I've had to use a 1.5 or 2mm drill bit, turned gently in the stub until it is clear, then carb cleaner to dislodge the remaining carbon. I've lost count of the number of Vauxhalls I've given this treatment to. Fit a new hose after checking you can feel vacuum with the engine running.

- Engine not hot enough. Gauge should show at least 90 degrees if marked, or approximatly 1/3 to 1/2 of full scale. Drive hard for at least 20mins immediatly before testing. If temp guage reading is still low then replace the thermostat.

- Coolant temp sensor dodgey (not very likely in my experience, but check and clean the connector if required).

Even if it does have a CO potentiometer on the air flow meter, still check the above first else you'll simply be curing the symptom rather than the cause of the fault. Maladjustment could cause many other problems including the ECU entering limp home mode.

I don't know about the Carlton, but on a 2.0 cavalier the lambda sensor is fitted under the car just before the cat. In that year you probably don't have a cat though.

HTH James of Sunderland

Reply to
James

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