NCT tomorrow

Damiencm

Hi all. My o/h has her nct tomorrow and I have a couple of questions.

First of all, i have bought a 250ml bottle of redex and on the back it says tonuse half the bottle in a full tank. However a few people have told me to throw in a full bottle on half a tank! Any got advise to share? Her half tank is half full at the moment and she wasnt planning on topping up.

Lastly, some of the paint has bubbled on the front wheel arch and there is a bit of rust showing on the surface. Is this a fail?

Atlantic Dawn

If there's nothing wrong with the car now, why ad redex? Surface rust will be fine once it's not sharp and a risk to pedestrians.

Toyotafanboi

i wouldn't add redex now. doesn't it temporarily raise emissions while it's removing the carbon deposits etc, or is that another internet myth?

Damiencm

Toyotafanboi wrote:

i wouldn't add redex now. doesn't it temporarily raise emissions while it's removing the carbon deposits etc, or is that another internet myth?

I have no idea to be honest. I threw some into the tank last year and it passed. I suppose i just thought it would do no harm. Its an 03 Hyundai Coupe that has seen better days.

punisher5112

Drive car hard on motorway burn out the crap and arrive at test centre with engine hot.

Damiencm

So had the NCT and failed on the emissions!

Came out at .31% with the limit being .20%. Fuel tank was about a 1/4 at time of test.

Am i way off the limit or would a tank of fuel and more redex help?

mullingar

If thats your CO level, then you should have put that money into a service as its running rich or a leaky exhaust.

Whats the Lambda level? Whats the HC level? Actually, throw up ALL values, high & low idle for a better opinion

Damiencm

mullingar wrote:

Whats the Lambda level? Whats the HC level? Actually, throw up ALL values, high & low idle for a better opinion

Thanks will put up the results when I get home tonight. Car had new plugs, air and oil filter and oil change before test.

Could it be the exhaust pipe itself?

mullingar

Yes, A leaky exhaust will cause an artificially high CO.

Damiencm

Exhaust Emissions:

Low Idle -

- CO .17% ( range above .30% fail)
- HC 14ppm (n/a)


High Idle - Lambda 0.99 (range 0.97-1.03)

- CO .31% ( range above .20% fail)
- HC 18 ppm ( range above 200 ppm fail)

mullingar

With those values, it's either a leaky exhaust or a faulty catalytic converter.

Jasper79

Sorry for hijacking thread my 1.4 vw Passat failed the nct at weekend too on emissions. It was serviced 4k km ago.

Low idle was posted a pass Co 0.24% vol

High idle was fail 0.82% co at 2.814rpm.

Anybody any ideas why such a big difference?

mullingar

What are the rest of the values?

Jasper79

mullingar wrote: »

What are the rest of the values?

Enigine oil temp 89.

Low idle hc 11ppm

High idle lambda 0.98
High idle hc 12ppm

John T Carroll

Jasper79 wrote: »

Enigine oil temp 89.

Low idle hc 11ppm

High idle lambda 0.98
High idle hc 12ppm

I presume its the 123 BHP TSI??, did the service include changing the plugs?, these are quite expensive, I replaced them at 164K Kms in my daughters Passat, they were NGK Platinum Premium (€60), the old ones still looked perfect.

Jasper79

John T Carroll wrote: »

I presume its the 123 BHP TSI??, did the service include changing the plugs?, these are quite expensive, I replaced them at 164K Kms in my daughters Passat, they were NGK Platinum Premium (€60), the old ones still looked perfect.

Yes that's the one. Yeah it was a full service so plugs so should have been done.

John T Carroll

Jasper79 wrote: »

Yes that's the one. Yeah it was a full service so plugs so should have been done.

The low Lambda of 0.97 (should be 1.0 in a perfect world) and high CO indicates a rich mixture which could be caused by any number of things. I presume that whoever changed the plugs, replaced them with the correct ones and had the correct tool to remove the wiring harnesses as it is easy enough to damage them but the car probably wouldn't be driving well under normal conditions if this was the case.
I would suggest getting a diagnostic test done, you can take a generic OBD with a VCDS which will give very useful info re the state of both O2 sensors (Lambda) and the long and short term fuel trims. I took them on the Passat at around 180K Kms and yours should look pretty similar I would think. As I haven't done any major work on this car/engine re emission issues I am afraid I cant offer any meaningful words of wisdom except maybe to clean the throttle body.
If you are in the Cork area (but not tomorrow!) I can get hold of a VCDS at short notice and do that test for you no problem.

Jasper79

John T Carroll wrote: »

The low Lambda of 0.97 (should be 1.0 in a perfect world) and high CO indicates a rich mixture which could be caused by any number of things. I presume that whoever changed the plugs, replaced them with the correct ones and had the correct tool to remove the wiring harnesses as it is easy enough to damage them but the car probably wouldn't be driving well under normal conditions if this was the case.
I would suggest getting a diagnostic test done, you can take a generic OBD with a VCDS which will give very useful info re the state of both O2 sensors (Lambda) and the long and short term fuel trims. I took them on the Passat at around 180K Kms and yours should look pretty similar I would think. As I haven't done any major work on this car/engine re emission issues I am afraid I cant offer any meaningful words of wisdom except maybe to clean the throttle body.
If you are in the Cork area (but not tomorrow!) I can get hold of a VCDS at short notice and do that test for you no problem.

Thanks for that plugs were changed in my regular garage been using for years so don't think they'd use wrong ones . thanks for the offer am in Dublin though I've friend lined up to hook it up to computer after Christmas so hopefully shed some light on it and won't be anything major