I have a 2000 1.8 Gdi Carisma which has just failed the MOT on Emissions. Well to be more precise a high CO
Apparently the CO level for fast idle should be 0.300, I have 0.454 and 0.418 for the 1st and 2nd test.
The natural idle should be 0.500 mine was 0.870. Both the hydrocarbon and Lambda readings were in the centre of the permitted range.

I know that these engines are prone to carbon build up and clogged injectors, but does anyone have any idea what area I should be looking at. Two other bits of information theres 77000 on the clock and it was due a service at 75000.

I had a look at the air filter and it it in need of replacement, but I haven't looked any further that that yet, as it was due a service and MOt at the same time.

Unfortunately the garage didn't seem overly helpful and suggested I would be better scrapping the vehicle, and that it would not be worth servicing. (bit harsh as it only failed on the emissions).


Andy

They told you to scrap it!!!Wow!Thats crazy,cars only 7 years old with not that many miles!Poor garage

Id say you should give the car a full service,it may not solve the problem but it means you know everything is sound and what it wont be the cause of any problems

Excessive Co results normally mean rich air/fuel mixture.Its likely you will find you have a problem with the injectors(these tend to give trouble as you said)But dont rule anything out till youve checked it all.

you could try some 10K (you can get in halfords). This will displace some built up carbon

Right, having spent what appears to have been a productive weekend I think things are heading in the right direction. I changed the filter and cleaned the plugs (new ones on their way). Cleaned up the throttle body, inlet manifold and valve chambers. I know that they carbon up, but I was surprised by how much.
After sticking everything back together it fired up.

When the initial 'clearing' had settled I noticed the revs to be a touch high (1000-1500) but have put this down to the engine working better, but would like to get it back to the 750 region. I can't seem to find an adjuster screw, and having looked through the service manual think that this is something the main dealer has to deal with as It seems to be set up with the diagnostics.

The only other problem I have become aware of is the management light coming on when the engine has been idling for a good while (I've only had this once before and that was after being stuck in very slow moving traffic , so both are low rev stuff). Any ideas?

Thanks for the previous advice; I didn't have much of a clue before. I was just stumped as to why it was only the CO reading was high.

Hi Pandibar

To reset the base idle you need to disconnect the battery leads and short the terminals (hold them together - the leads not the battery!) for a minute or two - this will reset the ECU (your engines computor). Reconnect the battery.
Then run the engine for ten minutes with nothing electric turned on, turn off the ignition - restart and run for ten minutes with the air con on high, then restart. Take it on a run - a motorway is very useful - and it should be right.
Be warned that when I did this, it took about 200 miles before it settled down properly (tho' I was getting fantastic economy).
It may be the other way around - 10 mins with aircon, then ten without anything - check with a mitsubishi service dept. But there's no adjustment screw! ;)

How did you clean your valve chambers and inlet manifold?
I need to do mine - was it straightforward?

The hard way I'm afraid, although it was fairly simple. I removed the throttle body and used a carb cleaning spray with lots of elbow grease, but did not strip the body down.

The manifold was removed, sprayed with the carb cleaner and left for a bit. I then pressure washed the inside. there is also a flange on the underside which has air channels that emerge on the inside of the manifold just behind the throttle body flange. These were fairly gummed up. When this was finished, it was allowed to dry.
With the manifold removed the valve chamber area is accessible.
Once again the carb cleaner was let loose. I pushed a small cloth into the chamber, but be careful not to push it in too far as you may not be able to remove it afterwards. This was to block the lower chamber from the carbon dposits from higher up. I found that the carb cleaner seemed to work alot better if allowed to soak in for a while. The other advantage with the lower cloth is that the carb cleaner can soak through it alowing it to work on the bits you can't reach. Then using a clean cloth for each of the valve chambers removed the most oil carbon mix by finger and firm bristle brush. (bit like a toothbrush.) Once the had all been cleaned blocking cloth was removed,I used another clean dry cloth pushed as far into the chamber as possible, left it to soak up any residue for a while . if it came out fairly dry and clean (relatively speaking)that was it. If not the initial cleaning process was repeated. Its then just a case of fitting everything back together and new gaskets.

Then start it up. It can take a while, but no more than any other car after this type of work. For me the result was a smoother running engine (the hunting had disappeared), although the 'soot' coming from the exhaust initally, was unbelievable.

Andy