Another VW Polo with high emissions

BorneTobyWilde

Vw Polo, belongs to sister.
Failed test on high emissions as it does every year along with every other VW Polo with same engine.
It's a 1.2 2004
They really are a funny little engine.

Cat was replaced last time. I can imagine there is an under lying problem

nd

Your Lambda reading is very rich so I'd first check for intake + exhaust leaks.

jca

BorneTobyWilde wrote: »

Vw Polo, belongs to sister.
Failed test on high emissions as it does every year along with every other VW Polo with same engine.
It's a 1.2 2004
They really are a funny little engine.

Cat was replaced last time. I can imagine there is an under lying problem

Yep, the engine is toast. Try and source an engine from a later car. They're an absolute dog of an engine, they seem to be made from recycled washing machines with valves and valve guides made from MDF.

BorneTobyWilde

jca wrote: »

Yep, the engine is toast. Try and source an engine from a later car. They're an absolute dog of an engine, they seem to be made from recycled washing machines with valves and valve guides made from MDF.

Drives fine, burns very slight drop of oil over the course of 3 months.
Does not over heat or use water. I really would not fault the complete engine.

jca

BorneTobyWilde wrote: »

Drives fine, burns very slight drop of oil over the course of 3 months.
Does not over heat or use water. I really would not fault the complete engine.

With a CO value that high and excessive smoke on the fail sheet it obviously isn't fine. It was so bad they didn't do the high rpm test, I wouldn't put another shilling into that car unless it's to replace the engine (if you can find one).

whizbang

You might get away with it with a heavy dose of oil treatment into a 20/50 oil.

*Let her cool down as much as possible before doing the test*
- almost cold will reduce the amount of oil being burned.

Jack the Stripper

whizbang wrote: »

You might get away with it with a heavy dose of oil treatment into a 20/50 oil.

*Let her cool down as much as possible before doing the test*
- almost cold will reduce the amount of oil being burned.

Blag it through a test and let it pollute the planet for another year, youre a winner alright.

nd

Would it running very rich due to for example a bad lambda sensor not cause excessive smoke?

BorneTobyWilde

Excessive smoke must be a NCT term. Car does not smoke whatsoever, zero visible smoke.
Not as if it's burning oil and there is blue smoke.

nd

Just from looking at the sheet my guess would be that your front lambda sensor is bad. You could try swapping the front and back sensors if you don't want to spend any money on it. That worked on my brothers Clio.

mullingar

If the high idle was measured at just 520rpm and it has a HC value of 120, I would wager that any rev over 1000 would exceed that max HC limit of 200.

Also with that lambda(CO) reading so bad, first thing to do is check for exhaust leaks, then get teh O2 sensors checked and appears that one might be faulty. This may fix the CO levels, but not the HC.

Hunter321

I hope you don't mind me hijacking the thread Borne. I brought in my 06 Polo today and failed the emissions as per below. Doesn't seem as bad as OPs but similar lambda reading. When I first saw that I thought the oxygen sensor. The NCT guy said he could smell the 'CAT'. He suggested some diopane (I think that's what he said) and bring it back in. I don't want to bring it in to fail again so would prefer to try diagnose the problem. It does burn some oil and has since I git it three years ago, this is the first time it failed NCT. Any help appreciated.

Low Idle: CO 0.46%, HC 27 ppm
High Idle: Lambda 0.92, CO 2.39%, HC 303 ppm

BorneTobyWilde

Sister got CAT fitted. Mechanics always go for that part first, and they're the ''experts.''
He saw fail sheet and did not mention Lambda or sensors.
Will be retested tomorrow with a promise of a pass.

Hunter your car seems close enough to pass with diopane added, you would need to add it and drive it for 100 miles I would guess. The maybe add another and drive it hard, retest when hot and after a good drive. I'm just guessing though.
It's not as bad as my sisters car that's for sure.

Hunter321

Good luck tomorrow, the CATs are not cheap, hope it passes. I'm wondering the fact that the lambda is low, does that point to the oxygen sensor. One of the posters mentioned swapping the front and back sensors, not sure how that would work, but must be worth a try. I also saw posts on other forums of measuring the voltage to the sensor to get an idea if its faulty. Not sure what would be a normal voltage though.

jca

BorneTobyWilde wrote: »

Sister got CAT fitted. Mechanics always go for that part first, and they're the ''experts.''
He saw fail sheet and did not mention Lambda or sensors.
Will be retested tomorrow with a promise of a pass.

Hunter your car seems close enough to pass with diopane added, you would need to add it and drive it for 100 miles I would guess. The maybe add another and drive it hard, retest when hot and after a good drive. I'm just guessing though.
It's not as bad as my sisters car that's for sure.

Getting a new cat fitted might get you a pass but you really need to find out what's poisoning the cat, or you'll be back to square one next year.

nd

I'm almost certain the cat has no effect at all on the lambda reading. Which is basically the air fuel ratio(from what I understand).

So given that she'd a lambda value of .92 and the acceptable values are .97 to 1.03 I don't think she'll pass. But I hope I'm wrong.

.92 is very rich and from my experience will throw off the co and hc values massively.

grogi

jca wrote: »

With a CO value that high and excessive smoke on the fail sheet it obviously isn't fine. It was so bad they didn't do the high rpm test, I wouldn't put another shilling into that car unless it's to replace the engine (if you can find one).

If a petrol car is smoking, but not burning oil, the mixture is far too reach. Probably the injector(s) is leaking.

jca

grogi wrote: »

If a petrol car is smoking, but not burning oil, the mixture is far too reach. Probably the injector(s) is leaking.

Correcting the lambda to bring it within the pass tolerance might improve the CO figure i.e. leaning out the fuel air ratio but I guarantee you it's No.3 cylinder has worn rings/ valves or valve guides that's at the root of the problem and until that's sorted you can feck around with cat's, oxygen sensors, ignition coils and any other components until the cows come home but it'll never be properly cured. Even getting the head done by a machine shop is no guarantee it'll last, they're a horrible little engine that'll break your heart and your wallet.

nd

Not disagreeing with anything jca has said. They do seem to be sh!te engines.

grogi

jca wrote: »

Correcting the lambda to bring it within the pass tolerance might improve the CO figure i.e. leaning out the fuel air ratio but I guarantee you it's No.3 cylinder has worn rings/ valves or valve guides that's at the root of the problem and until that's sorted you can feck around with cat's, oxygen sensors, ignition coils and any other components until the cows come home but it'll never be properly cured. Even getting the head done by a machine shop is no guarantee it'll last, they're a horrible little engine that'll break your heart and your wallet.

Sure - easy check for compression on the cylinders will tell how much it is broken. As a method of last resort before absolutely sensless option of rebuiliding the engine, the OP could try a xado (or equivalent) product, exp. http://www.xadoireland.ie/revitalizant/16-atomic-metal-conditioner-maximum-with-1-stage-revitalizant.html

nd

How did she get on?

jca

grogi wrote: »

Sure - easy check for compression on the cylinders will tell how much it is broken. As a method of last resort before absolutely sensless option of rebuiliding the engine, the OP could try a xado (or equivalent) product, exp. http://www.xadoireland.ie/revitalizant/16-atomic-metal-conditioner-maximum-with-1-stage-revitalizant.html

The compressor test can sometimes indicate that everything thing is ok but it's the oil control ring that's badly worn.

BorneTobyWilde

nd wrote: »

How did she get on?

Passed. I don't know details of test sheet though.

The mechanic talked to tester before repair and said if new cat was fitted he'd pass it even if it's over the test limits........
Mechanic fitted new cat, fixed a worn brake pipe which was also on list, retested car, as in Mechanic brought it to test center and paid for retest.
The bill came to 430.00 all in, parts , labour, retest. Car came back to me with a years NCT.

grogi

jca wrote: »

The compressor test can sometimes indicate that everything thing is ok but it's the oil control ring that's badly worn.

But the car was not loosing oil, thus the oil control rings were fine.

If the compression is low - because of the valves or anything else, it means the air is getting out of the combustion chamber before the ignition. There will be significantly less compressed air in the cylinder than the ECU thinks there is. That actually would be consistent with the air/petrol mixture being far to reach we have seen in the emission test.

BorneTobyWilde wrote: »

Passed. I don't know details of test sheet though.

The mechanic talked to tester before repair and said if new cat was fitted he'd pass it even if it's over the test limits........
Mechanic fitted new cat, fixed a worn brake pipe which was also on list, retested car, as in Mechanic brought it to test center and paid for retest.
The bill came to 430.00 all in, parts , labour, retest. Car came back to me with a years NCT.

Good you're sorted. But OxiCat should not go in vehicle life, it failing is a symptom of something else. If there is unburned fuel getting into the exhaust, you'll have another Cat to replace next year...

Do you have the NCT results sheet?

jca

BorneTobyWilde wrote: »

Passed. I don't know details of test sheet though.

The mechanic talked to tester before repair and said if new cat was fitted he'd pass it even if it's over the test limits........
Mechanic fitted new cat, fixed a worn brake pipe which was also on list, retested car, as in Mechanic brought it to test center and paid for retest.
The bill came to 430.00 all in, parts , labour, retest. Car came back to me with a years NCT.

Stick it up on done deal with the new test and buy a Yaris.

BorneTobyWilde

grogi wrote: »

But the car was not loosing oil, thus the oil control rings were fine.

If the compression is low - because of the valves or anything else, it means the air is getting out of the combustion chamber before the ignition. There will be significantly less compressed air in the cylinder than the ECU thinks there is. That actually would be consistent with the air/petrol mixture being far to reach we have seen in the emission test.



Good you're sorted. But OxiCat should not go in vehicle life, it failing is a symptom of something else. If there is unburned fuel getting into the exhaust, you'll have another Cat to replace next year...

Do you have the NCT results sheet?

No test sheet. Sister probably has it.
I'll post it if I get it.

Cerebrum

Waste of a good new cat right there unless your sort it.

I've had one of these in already this year. Genuine VW parts had been thrown at it; new lambda, spark plugs, ignition coils etc. ECL was illuminating. My VCDS brought up several emissions codes. Removed the exhaust manifold and there were several fracture lines on it. Seems the manifolds are quite prone to splitting and air leaks upstream of Bank 1 lambda.
It may be weldable, but sounds like you've at least one sizeable hole for a 8% rich condition.

jca

I thought an upstream air leak put lambda in the other direction

Cerebrum

With a narrowband lambda sensor it can go either way. Currently the engine is far over-compensating for the excess oxygen streaming over the lambda, so the leak should be quite sizeable.
The exhaust gases can leak out or atmospheric gases may leak in depending on the hole and stream position.

If the condition has been ongoing for some time, you might/might not expect the zirconia tip on the lambda sensor to be poisoned also, further upsetting the condition.