Nct Failure (Emissions)

Hellrazer

Need a bit of advice here from someone that may have come across this before.

I cant seem to get the emissions down for an NCT due on Thursday.

So far the results are

CO is at 0.5-0.7
HC are at 500-600

Its all ove the place when I test it.

High CO is pointing towards a Cat but high HCs are generally not Cat related....more like all the fuel not burning or an ignition problem.
I know there used to be like an EGR valve that used to stick on these Coupes and as far as I remember it caused the emission to go haywire but I cant remember the details its that long since I left Hyundai.

Ive located a brand new cat at a decent price but Im still on the fence as to whether it is the cat or not.

Any ideas.

Its burning a small bit of oil but tbh Ive gotten through an NCT with worse oil burners--some that used more oil than petrol to be honest.
Ive tried all the usual tricks--dipethane,engine flush,full service and still no joy.
First time dipethane has let me down in all fairness


Car is Hyundai Coupe 1999 1.6
I have it well prepared--just done drop links,new brake lines,bushes but I just cant get the emissions down on the damn thing.

Eddie Smart

Hi Hellrazer,
I would start from the cat.convertor. The chances it is still alive are close to zero on '99 car. Don't blame the engine, those hyundai motors arent bad.

moodrater

check manifold they crack fooling the oxygen sensor and causing it to run rich
unburnt hydrocarbons overheat the cat so probably banjaxed anyway
If manifold is ok then the main lambda sensor probably fecked or it could be simply that the old cat is blocked from a previous problem
blocked cat would cause you to fail emissions and raise crankcase pressure and oil consumption
check that the pcv isn't blocked also as this will increase oil consumption

so inspect manifold, take off the existing cat and inspect it if its fecked knock the inside out of it and put it back on the car see if it runs ok

if its still running rich test the lambda sensor definitely don't put the new cat on without fixing the hydrocarbons it will overheat and go south very quickly

Hellrazer

moodrater wrote: »

check manifold they crack fooling the oxygen sensor and causing it to run rich

Manifold is grand--No cracks in it.First thing I ckecked--used to fix loads of them--liquid metal is great stuff

unburnt hydrocarbons overheat the cat so probably banjaxed anyway

More than likely but Im reluctant to fit a cat until I know whats causing the over fuelling.

If manifold is ok then the main lambda sensor probably fecked or it could be simply that the old cat is blocked from a previous problem

Would a faulty lambda not put the enging light on???Theres no faults on it according to the obd reader.

blocked cat would cause you to fail emissions and raise crankcase pressure and oil consumption

See thats what Im thinking--It may be blocked causing what you say.

check that the pcv isn't blocked also as this will increase oil consumption

I dont think this model has a PCV on it.

so inspect manifold, take off the existing cat and inspect it if its fecked knock the inside out of it and put it back on the car see if it runs ok

The car is running fine as it is--theres no lack of power at all.Theres no smoke out the back of it either.I cant even be sure that valve seals/rings are letting oil through.

if its still running rich test the lambda sensor definitely don't put the new cat on without fixing the hydrocarbons it will overheat and go south very quickly

Lambda is what Im leaning towards--but then theres no faults on the reader.Also I only want to get this through the NCT--Im going to de-cat it as soon as its passed.Screw the HCs after that

Also the cat is a manicat on this thing--manifold and cat all in one--whats the general opinion of weld in cats---Its been recommended to leave the existing one in place and weld in a new one onto the exhaust just behind the one thats there.
Do they work???Will it get the CO down??

AzureAuto

Hi Hellrazor,
Id recommend to get some live data on the function of the pre-Cat lambda sensor. The results indicate she's running very rich. Get her warmed up and scope the output of sensor. Waveform should fluctuate no lower than 0.2 V and no higher than 0.9 V.
Possibility that emissions are high due to fouled sensor, however the EML hasn't been illuminated because its still working within acceptable parameters (from ECUs perspective if you follow).
Talking from experience, have changed a few out due to similar circumstances. If it does prove to be the sensor, use a genuine make, as some spurious sensors are rubbish.

Hellrazer

Just back from the NCT.

Failed on emissions (as I thought) but passed on everything else.

Heres the read out.

Low Idle
CO 0.50%--Pass
HC 184 ppm---Pass

High Idle
Lambda--1.01----Pass
CO 0.59%---Fail---Should be 0.2% or below
HC 91ppm.

So it looks like the Hcs have come down from the engine flush I did on yesterday and the dipethane in the tank before the test.The car is not burning oil as I previously thought--think the lads did a compression test and it was fine.

That CO is bothering me though.

All data is leading to the Cat being gone.

So back to my original question---Will a weld in universal Cat work??Mine is a manifold/cat all in one and is 700-800 main dealer.
I can get a universal weld in supplied and fitted after the existing cat for just over 100 euros.

With regards to the sensor--My diagnostic wont read this model.Its pre-obd so I need an older diagnostic machine which I have a loan of for the weekend--Ill test the sensor then.

Eddie Smart

That data from your nct report tells about cat is gone. Two ways to fix.
1. you will fit universal one as close as possible to the engine. It might not help on the first acceleration because the operating temperature won't be reached. The best idea to ask nct mechanic who will take your car to accelerate a few times to get the result.
2. a bit more hassle, but the result is guaranteed. The mechanic whom I know did it a many times and it works as new. So, you have to take a manifold with old cat and then remove the old core by cutting the cat's body on one side (use 1mm grinder metal cutting disc). Then you have to take ceramic core from new cat by same way and fit it in the original manifold housing. Some DIY welding skills required to fit all bits and pieces together properly (new core should be adjusted to sit tight enough) Then on your new nct report you will see CO 0.01-0.1% I hope my tip will help.
That mechanic charges 250 euro for the job including his proved new cat convertor.
Let me know if you need any info.
Eddie.

Eddie Smart

Sorry, I forgot to say about measuring your lambda..
Don't waste your time, with lambda figure 1.01 in the report and no check engine light on- 99% your oxygen sensor is ok.

Chimaera

Could you not just cut the old cat off from the downpipe and weld on the new one in it's place? Anyone half decent at welding should be able to pull it off.

couldntthink

Eddie Smart wrote: »

The mechanic whom I know did it a many times and it works as new. So, you have to take a manifold with old cat and then remove the old core by cutting the cat's body on one side (use 1mm grinder metal cutting disc). Then you have to take ceramic core from new cat by same way and fit it in the original manifold housing. Some DIY welding skills required to fit all bits and pieces together properly (new core should be adjusted to sit tight enough).
Eddie.

I'm not trying to be a smart ass, but this sounds like nonsense. I have cut a lot of cats, but I have yet to see or hear of someone removing a core and fitting it in a different body.

There isn't a snowball's chance in hell of someone doing that and being successful.

moodrater

Cat reduces hydrocarbons too so if cat is defective then new one will take care of both. I'd definitely have a look at the egr before cutting and welding though.

Regarding the universal cats they work alright some are low quality. I know panel beater in cork that fits the universal ones they were of varying quality he had problems with the same model/size performing 1/3 as well as another. Now he buys a stock of smaller size welds one in checks emissions with snapon welds in another if still too high cheaper than keeping a stock of all different sizes but it looks pretty funny if you end up with 3 cats like a string of sausages.