Emissions fail nct

vince

Hi any tips my 98 megane failed emissions 5.45 co on first test so replaced cat and retest showed co 0.45 since retest I have replaced lamba sensor cleaned plugs and leads and distributor cap inside put additive in tank etc . During all this tinkering I took 6 emission tests in a garage but cant get reading below co 0.33 and limit is below .30 at high revs. Any advice welcome its very annoying alot of money spent now too.

Kopparberg Strawberry and Lime

Clean throttle body and literally red line it on the motorway

as it put into 3rd gear and get the revs all the way up with less than quarter of a tank and fuel additive

then when your at NCT again, give them 1 key and with the other key sit in the car with the engine running so that its nice and hot when they take it in, revving it while waiting too at about 4,000 revs !

Nino Brown

Kopparberg Strawberry and Lime wrote: »

Clean throttle body and literally red line it on the motorway

as it put into 3rd gear and get the revs all the way up with less than quarter of a tank and fuel additive

then when your at NCT again, give them 1 key and with the other key sit in the car with the engine running so that its nice and hot when they take it in, revving it while waiting too at about 4,000 revs !

I knew having the cat hot during the NCT worked, but sitting in the car before hand with the other key revving the sh!te out of it is genius.

vince

Ive been racing her all week 4000 plus before doing garage emission tests on one test she breifly dropped to 0.27 co the last 2 emissions tests show 0.33 co it possibly the new cat is faulty seeing as it needs to be so hot to get levels down? . Realy annoying shes always been well below limits on the 7 ncts ive put her through. Sadly no spare key to run her at nct centre. Knowing my luck next nct they ll probly leave my car out side for 10 mins getting cold.

Kopparberg Strawberry and Lime

vince wrote: »

Ive been racing her all week 4000 plus before doing garage emission tests on one test she breifly dropped to 0.27 co the last 2 emissions tests show 0.33 co it possibly the new cat is faulty seeing as it needs to be so hot to get levels down? . Realy annoying shes always been well below limits on the 7 ncts ive put her through. Sadly no spare key to run her at nct centre. Knowing my luck next nct they ll probly leave my car out side for 10 mins getting cold.

What car is it ? what engine ?

do you find its drinking too much oil ?

how is it on petrol ?

i assume you did the usual oil + filter + Air filter ?

vince

1.4 megane renault petrol. 38 mile to gallon never need to top up oil i change every 7000 mile oil and filter. During most the emission tests ive had the air filter box off looking at pipes etc so plenty of air. Also removed vent pipe from rocker box cover to airfilter box. And tried whit oil cap off. Havent tried temp sensor tho. Getting fed up of buying bits that I dont need after.

Kopparberg Strawberry and Lime

vince wrote: »

1.4 megane renault petrol. 38 mile to gallon never need to top up oil i change every 7000 mile oil and filter. During most the emission tests ive had the air filter box off looking at pipes etc so plenty of air. Also removed vent pipe from rocker box cover to airfilter box. And tried whit oil cap off. Havent tried temp sensor tho. Getting fed up of buying bits that I dont need after.

tricky so it is.

all i can say is keep the fuel level below quarter of a tank and put the fuel/engine cleaner and keep it driving right on the red line for a long distance.

vince

Yea cheers have some in atm. Just thinking what next step is book another nct another 55euro or put into a proper garage and see if they can sort it. This was to be my last test on her buying new car next year typical.

toyotaavensis

another option could be to run the car on dipetane instead of petrol when it is going for the test.

vince

The fun continues still getting high emission results from tests at garages. New bosal cat new lambda censer (Not renault) plugged in and all seems fine. Today I put another throttle body on and results still hgh co0.4. My first nct results were low idle co 0.62 lambda 0.87 high ideal co 5.04 and hc 179 ppm.
results of 2nd nct whit new cat installed low ideal co 0.67 lambda 1.01 high ideal 0.48 and hc 19. After this I tried all the other bits and took to 2 differant garages for emission tests.
Car is running like a clock getting very fed up now. Im going to try another new cat on her next week

Kopparberg Strawberry and Lime

I can only think of keep working backwards.

How's the exhaust manifold and gasket ?

If the car was using too much oil you might say o rings, head gasket etc.

vince

No leaks in pipe. And uses very little oil I never need to top up in the 7000 miles between oil and filter changes.

Kopparberg Strawberry and Lime

vince wrote: »

No leaks in pipe. And uses very little oil I never need to top up in the 7000 miles between oil and filter changes.

Is the timing ok ? Didnt jump a few teeth or anything ?

b318isp

Have you checked for vacuum leaks or a faulty air-flow meter?

The problem seems to be specific to the fuel/air ratio, so I'd check everything on the intake side of the engine given you have already focused on the exhaust side.

vince

Tried altering the timing while I had it on the emissions reader. Checked vacum pipes and all seems fine. Its an odd one