Nct - Cat Problem

luckyD

Hi guys,

sending the car in for the nct on fri. its a vw bora 04', 1.4l ex taxi with 114,000 miles on it. brought it to my mechanic last week for a full service and pre nct. he said that all was grand bar the emissions and that they were through the roof. i had noticed a funny smell coming from the exhaust when starting it up on cold mornings but thought nothing of it really. anyway my mechanic says to come back the morning of the test and he'll align the lights etc etc and put flush into the car. he then said an hour before the test to drive her and i quote "Like she's stolen" to get the flusher kicking into the system and have it red hot heading into the test.

does anyone reckon that this will do the trick or will i be facing forking out on a new cat? if so how much would i expect to pay? I'm checking around on the net and seems that 60 pounds for a universal one is the cheapest. they seem to go up to 200 euros.

thanks for the advice.

SAABMAN

Worked for me:D
Emissions were something like 67 (can't remember exactly), changed plugs and oil, fixed a tiny leak in a vacuum pipe, kept it in 3rd and 4th and the revs high all the way to the test (30 miles) and it passed. Emissions .15

Matt Simis

Running hot via high RPM, running on E5 and maybe dropping in Dipetane (if testimonials here are to be believed) will likely get you through the NCT. But seriously, dont you think you should actually attempt to fix a serious engine problem thats likely robbing power and economy?

Those cat prices your quoted seem way too cheap IMO too. The problem may not even be the cat, it may be a symptom of something else.

luckyD

cheers for the info guys. defo considering getting it fixed properly alright, the car does seem more sluggish that any other 1.4 I've driven. anyone got any idea of how much a decent cat will cost for it so?

thanks again

BrianD3

Driving a car "like it's stolen" prior to an NCT generally won't do anything for a serious emissions problem and your mechanic did say that your emissions are sky high. Your lambda sensor or cat could be knackered, seeing as the sensor is cheaper you should focus in on that before the cat. But some systematic diagnosis should be done rather than starting to replace parts and hoping to stumble on the right one.

Also, IIRC, the 1.4 engine in your car can have problems with excessive oil consumption, if you need to top up your oil regularly and also have high HC emissions that could be an ominous sign for your engine....

Scottie99

http://www.dipetane.ie/

Add some of this stuff to your tank, this will help. Worked for me!

Darragh29

This is pretty much the same engine that is in the Golf, and they're known to be difficult at times to get through the NCT for emissions unless the engine is hot. You should be OK once you make sure that the car has had a good drive before the NCT test. I wouldn't be putting a cat into it this side of an NCT fail anyway...

Darragh29

BrianD3 wrote: »

Driving a car "like it's stolen" prior to an NCT generally won't do anything for a serious emissions problem and your mechanic did say that your emissions are sky high. Your lambda sensor or cat could be knackered, seeing as the sensor is cheaper you should focus in on that before the cat. But some systematic diagnosis should be done rather than starting to replace parts and hoping to stumble on the right one.

Also, IIRC, the 1.4 engine in your car can have problems with excessive oil consumption, if you need to top up your oil regularly and also have high HC emissions that could be an ominous sign for your engine....

The emissions will be sky high until the engine heats up. This is normal on this make/model.

Matt Simis

Darragh29 wrote: »

The emissions will be sky high until the engine heats up. This is normal on this make/model.

Its assumed the mechanic knows that and emissions were high when the engine is hot. The NCT and MOT dont test cold start emissions (making pre-cats in various cars completely counter productive).

BrianD3

Matt Simis wrote: »

Its assumed the mechanic knows that and emissions were high when the engine is hot. The NCT and MOT dont test cold start emissions (making pre-cats in various cars completely counter productive).

That would be my thinking too, surely the mechanic didn't only test the car cold. If he tested it cold, and didn't bother doing it hot but instead speculated that revving the balls off it before the NCT would "probably" lower the emissions - then he's not a very good mechanic.

A modern petrol car should be pretty warm after 5 minutes driving from a stone cold start. I don't know what sort of emissions would correspond to say, an engine oil temp of 40 degrees C. Would be interesting to see a graph of engine emissions vs oil temperature vs water temperature vs cat temperature (if that's possible to measure) for a car with a fully functioning cat and engine.

beachlife

BrianD3 wrote: »

That would be my thinking too, surely the mechanic didn't only test the car cold. If he tested it cold, and didn't bother doing it hot but instead speculated that revving the balls off it before the NCT would "probably" lower the emissions - then he's not a very good mechanic.

A modern petrol car should be pretty warm after 5 minutes driving from a stone cold start. I don't know what sort of emissions would correspond to say, an engine oil temp of 40 degrees C. Would be interesting to see a graph of engine emissions vs oil temperature vs water temperature vs cat temperature (if that's possible to measure) for a car with a fully functioning cat and engine.

it will make a difference. 5 minutes after a stone cold start???? a cat only works 100% when it's up to FULL temp which can take up to 20 minutes !! drivin' like it's stolen does two things first it heats up the exhaust (the cat can get to 450 ) and it can clear any lose carbon /soot .so your man knows what he's talking about