Emissions sky high (HELP!)

[PIRTEKMAN]

Hi all,My car has been sat in my garage for about 6 weeks as the mot ran out.It has been started regularly and idling for a while.When i took it for mot the emissions were 11% co and hc extremely high.I have been posing questions on what it could be and have spent hours fiddling and tinkering unplugging things,plugging them back in .Changed spark plugs,cleaned contacts on things etc.All this was to no avail as when i put the probe up the exhaust i kept getting 5% and more on the co.As a last resort and fed up to the back teeth i decided to risk taking it out and gave it a good thrashing up the road ,round back country lanes and revved the hell out of it(**** or bust).I just got it back home put the co meter up the exhaust and now reading 1% co.Could it just have been because the car has not been run on the road for so long that the emissions were so high.Just hope they remain low for the mot.Thanks for all your assistance and keep up the good replys you give.The advice is really appreciated.Thankyou Alan.

[E_T_V]

The engine has to be up to working temperature for the emissions to be correct.

[PIRTEKMAN]

The engine has to be up to working temperature for the emissions to be correct.

I would have thought that leaving the engine running untill fan has kicked in and temp half way was working temp.Cheers Alan.

[E_T_V]

Should do yes so long as it isn't a diesel!.

If could be down to plug fouling or perhaps a HT lead breaking down giving a slight misfire. These then dry out as the engine spends time at temperature and suddenly the problem goes away. The K series was a sod for doing that.

[PIRTEKMAN]

Took car a run round tonight ,tested emissions and guess what,SKY HIGH again.Something is intermitently causing engine to run rich.Have put new plugs in,new ignition leads,has been reading around 1% co this last few days.MOT at 11.00am in morning,looks like failure again.

[E_T_V]

Make sure the connectors for the coolant temp sensor is good, clean and tight and you may be lucky!

Make sure it is really hot for the test too.

[PIRTEKMAN]

Make sure the connectors for the coolant temp sensor is good, clean and tight and you may be lucky!

Make sure it is really hot for the test too.

OK.Have tested cts with an ohmeter and its high when cold and low when hot so i think its working properly.Is there anything i can do to make the ecu think it needs to be running lean ie cts is in hot water.Engine seems to be running rough as now, and i've tried taking ht leads off one at a time but to be honest you can hardly tell any difference it sounds that rough.Last night it sounded fine.Will give it a blast up the road in the morning but dont hold out much hope i'm beginning to wonder if the ecu is at fault.

[E_T_V]

If its misfireing then nothing you do to the CTS is going to help.

You need to fix the misfire first. I presume plugs, rotor arm and HT leads have been swapped for new ones (or at least known good ones).

[PIRTEKMAN]

If its misfireing then nothing you do to the CTS is going to help.

You need to fix the misfire first. I presume plugs, rotor arm and HT leads have been swapped for new ones (or at least known good ones).

Plugs and ht leads have been renewed with new items this week,All plugs when removed are sooty but not wet.I feel like i'm buying parts for the sake of it,prob nothing wrong with the ones i took off.I could buy new cap and rotar arm to find its still the same but no other way of proving anything i suppose.Cheers Alan.

[fbm777]

I just got my CO emissions down from 4.5% (fail) to 1.38% (pass) by doing the following to my 90K miles EFI.
(a) Put engine flush in the petrol (tank 1/3 full) and use it all up on motorway driving at 70mph till tank empty light comes on.
(b) Refill tank with premium grade unleaded.
(c) Silicone grease on inside of petrol filler cap rubber seal to create air tight seal.
(d) Replace engine oil.
(e) Replace and reconnect air flow sensor inside filter housing (it had become electrically detached from filter housing but also looked in poor shape)
(f) Clean ECU multiplug with electrical switch cleaner.

I don't know the specific issue but whatever I did it obviously worked.

[Jeff Turbo]

I just got my CO emissions down from 4.5% (fail) to 1.38% (pass) by doing the following to my 90K miles EFI.
(a) Put engine flush in the petrol (tank 1/3 full) and use it all up on motorway driving at 70mph till tank empty light comes on.
(b) Refill tank with premium grade unleaded.
(c) Silicone grease on inside of petrol filler cap rubber seal to create air tight seal.
(d) Replace engine oil.
(e) Replace and reconnect air flow sensor inside filter housing (it had become electrically detached from filter housing but also looked in poor shape)
(f) Clean ECU multiplug with electrical switch cleaner.

I don't know the specific issue but whatever I did it obviously worked.

Air flow sensor would cause that

[fbm777]

Air flow sensor would cause that

I suspect that it would, but I've had problems with emissions in the past even where the airflow sensor was properly attached. The garage had to decrease the idle speed to only just get it to pass on emissions then, although it could have been exacerbated by a dirty air filter. I like to think here that everything I did had a cumulative effect in decreasing emissions to well below 3.5% max. I am certainly happy with the result.