Exhaust emissions failed NCT

midajoh

Guys is there any way possible to lower the emissions?
Just done my NCT and failed,any help would be really appreciated.

keyboard_cat

What car is it?
is it burning oil at all?
When was it last serviced?

Atlantic Dawn

Looks at the basics first, when were spark plugs, oil and air filters changed?
Is the car burning oil?
Any warning lights appearing on the dash?
Is the car running rough or burning excess fuel to normal?

midajoh

Atlantic Dawn wrote: »

Looks at the basics first, when were spark plugs, oil and air filters changed?
Is the car burning oil?
Any warning lights appearing on the dash?
Is the car running rough or burning excess fuel to normal?

Its a Chevrolet Tacuma 1.6 petrol, I'm due a service this coming week, and yes it seems to be very hard on petrol. Everything else seems to be fine,no warning lights coming on.

keyboard_cat

midajoh wrote: »

Its a Chevrolet Tacuma 1.6 petrol, I'm due a service this coming week, and yes it seems to be very hard on petrol. Everything else seems to be fine,no warning lights coming on.

Well looking online those cars dont seem to get great mileage <30mpg are you getting around that?
perhaps just start with a service and get a bottle of Diptane to add to the petrol and drive it hard until the retest.
if that doesn't work and its not giving any engine management lights then its prob a bad catalytic converter

midajoh

keyboard_cat wrote: »

Well looking online those cars dont seem to get great mileage <30mpg are you getting around that?
perhaps just start with a service and get a bottle of Diptane to add to the petrol and drive it hard until the retest.
if that doesn't work and its not giving any engine management lights then its prob a bad catalytic converter

I put 50 euro in it this week, got roughly 220 miles and possibly might get another 10.
So to be honest not sure if that's good or bad?
Edit, just done some math and could be way wrong. I'm I getting about 20-25mpg?

PaddyWilliams

Personally, I think that's awful fuel consumption. Looking at your exhaust emission percentage, it's more than double the allowed amount. I'd say it would be very hard to get that down, but I'm no expert. I failed with my 2003 VW Golf a few years back, it was 0.22%. I put Diptane in it and drove it from Dublin to Kerry, dropping down to 3rd gear at times to try and clear out the exhaust as best I could and it just came in at the maximum allowable of 0.20%.

Atlantic Dawn

Official figures are about 35mpg

http://www.honestjohn.co.uk/carbycar/chevrolet/tacuma-2005/?section=data

midajoh

PaddyWilliams wrote: »

Personally, I think that's awful fuel consumption. Looking at your exhaust emission percentage, it's more than double the allowed amount. I'd say it would be very hard to get that down, but I'm no expert. I failed with my 2003 VW Golf a few years back, it was 0.22%. I put Diptane in it and drove it from Dublin to Kerry, dropping down to 3rd gear at times to try and clear out the exhaust as best I could and it just came in at the maximum allowable of 0.20%.

Might need a new cat, hope not.I have noticed the rev goes very high in between shifting gears.
Perhaps that one of the reasons for it's high consumption. Also hope a good service might help and adding that Diptane.

midajoh

Atlantic Dawn wrote: »

Official figures are about 35mpg

http://www.honestjohn.co.uk/carbycar/chevrolet/tacuma-2005/?section=data

Thanks for the link!!

keyboard_cat

midajoh wrote: »

Might need a new cat, hope not.I have noticed the rev goes very high in between shifting gears.
Perhaps that one of the reasons for it's high consumption. Also hope a good service might help and adding that Diptane.

Wait! when you put your foot on the clutch and take your foot off the accelerator and take it out of gear it revs high? and goes back to normal when you put it in gear and take your foot off the clutch?
Does it idle normally?
also are you sure the check engine light is not on ?

midajoh

keyboard_cat wrote: »

Wait! when you put your foot on the clutch and take your foot off the accelerator and take it out of gear it revs high? and goes back to normal when you put it in gear and take your foot off the clutch?
Does it idle normally?
also are you sure the check engine light is not on ?

Yes too all questions, and no engine light on.
Is there a valve that can turn down the high rev?
And thank you for your replies.

midajoh

Could the car running rich hurt the catalytic converters?

tomo92

If it revs when your pressing the clutch without touching accelerator it could be a vaccuum leak, and if it doesn't idle normal at a steady idle I'd clean the IAC valve if your car has one if not I'd be guessing a vacuum leak

keyboard_cat

Running rich would damage the catalytic converter eventually
But before doing that I'd be inclined to give it a full service throw some diptane into it and ask whoever is servicing it to check all the pipes from the air filter and clean out the iac valve as mentioned above and the throttle body which should take no more then 10 mins and a 5 euro can of carb cleaner
Also get them to give the maf sensor a clean (10 mins + 5 euro can of cleaner)
After all that if you are still failing on emissions then I'd guess you need a new cat