failed nct on emissions.... advice on dipthane.

120_Minutes

my car failed the nct on emissions (.39 when it should be below .3) and a rear window brakelight out (since fixed) and i've purchased some dipthane on advice. i've never used it, nor know how much to use. its out in the car right now so i cant check the label, how much should i use? my cars tank has a capacity of about 40L

I was also advised by a mechanic to "run it out the motorway a bit in low gear"
to get the revs up to get the dirt out....should i do this before or after the dipthane or both?

Nissan doctor

What were the full NCT emissions readings and what type of car is it.

120_Minutes

97 corolla 1.3

result is out in the car so cant check now, but the figures above are right, i was over by .09 and tester said i just scraped by on the lambda at (i think) 1.0

i know my car is old, but my petrol choice has been the same for the last 4 years (topaz) as i use their fuel card, if that info helps.

Thoie

120_Minutes wrote: »

I was also advised by a mechanic to "run it out the motorway a bit in low gear"
to get the revs up to get the dirt out

What's low gear in this instance? 120kph in 3rd gear?

120_Minutes

Thoie wrote: »

What's low gear in this instance? 120kph in 3rd gear?

i'd want to be very stupid to do that! 4th will do it....but i aint chancing it for long. ive never had it over 4000 rpm for more than a few seconds in the 6 years i've owned it.

Pottler

Dipethane more useful with diesels tbh but a quick "italian tune-up" and some fuel system cleaner(try tpt) might work. Sort the fundamentals first - fresh plugs, oil, air filter and then give the car a good blast - 30 km or so with a bit of a rev on:)

120_Minutes

Pottler wrote: »

Dipethane more useful with diesels tbh but a quick "italian tune-up" and some fuel system cleaner(try tpt) might work. Sort the fundamentals first - fresh plugs, oil, air filter and then give the car a good blast - 30 km or so with a bit of a rev on:)

well the car got 400 quid of a service before the NCT so i'm assuming thats pretty much done?

Pottler

120_Minutes wrote: »

well the car got 400 quid of a service before the NCT so i'm assuming thats pretty much done?

Brother in law runs one of these and I service it for him, once every three years, wether it needs it or not. I'm wracking my brain as to whats out of whack to give those high readings and all I can think of is that the injector is worn(think this is spi as opposed to mpi but cant remember)and is making it run too rich. Tried injector cleaner? Failing that, get the injector replaced. Colm will be on in a minute to point out that this has a carb or somthing, but he's usually right, so I can live with that!:D Cleaning out the throttle body carefully and methodically would also help but it could be somthing as simple as a failed thermostat or cold-start valve causing the engine to run too rich as not reaching correct temp/thinks its not..

How Strange

We had this problem with our previous car. I rang two mechanics; one said the catalytic converter needed to be replaced at a minimum cost of €650, the other said it would cost €250 to do something else.

I rang my dads mate who's also a mechanic and he advised us to fo the cheapest thing first. We got a certain type of engine cleaning liquid (can't remember the name but halfords sold it), put it in a full tank of petrol, drove it until the tank was empty, refilled, brought for a good spin on the motorway just before the test and it passed the retest. No problems with emissions.

Leonard Hofstadter

To be fair OP, none of us can really give you proper advice without seeing the full emissions readings. I'm know from the numbers that you're on about the CO emissions, but I don't know if they're low idle or high idle, and I also don't know what the HCs and lambdas are either:)!

Pkiernan

The "dupe-tane" and revving your engine suggestions are only solutions to a car that is barely failing emissions testing.

Most fails require real repairs.


OP, if you are borderline, dipetane may help. As to the amount you need, if in doubt dump the whole bottle in.

120_Minutes

Low idle, .18 high idle. 39 lambda 1.02

Neilw

120_Minutes wrote: »

i'd want to be very stupid to do that! 4th will do it....but i aint chancing it for long. ive never had it over 4000 rpm for more than a few seconds in the 6 years i've owned it.

That's probably your problem. Take it out for an Italian tune up
http://en.wikipedia.org/wiki/Italian_tuneup

120_Minutes

bump for actual emissions figures....

Leonard Hofstadter

What about the HC emissions OP? You're missing those!

I guess they're unlikely to be out by too much though, if at all considering how the lambda is within the limits (although it is running a bit too lean). On balance you're not massively out, a good lash of fuel cleaner plus a good spin down the motorway should help. Oh and drive the crap out of it on the day of the test - make sure the engine is good and hot going into the test centre:)!

coylemj

120_Minutes wrote: »

well the car got 400 quid of a service before the NCT so i'm assuming thats pretty much done?

Spending €400 on a 15 year old Corolla is total nuts. Proves the point that giving your car to a garage for a pre-NCT service & check is as good as giving them a blank cheque.

I drive mainly around town on short journeys but about every other week when the engine is up to operating temperature I give her a blast up to 5,000 RPM when it's safe to do so.

Chimaera

Was the car up to proper operating temperature when it was tested? It never ceases to amaze me how many people fail because the car went in stone cold and they spend a fortune trying to fix a problem that isn't there.

Big Nasty

Chimaera wrote: »

Was the car up to proper operating temperature when it was tested? It never ceases to amaze me how many people fail because the car went in stone cold and they spend a fortune trying to fix a problem that isn't there.

You would have to live less than a couple of miles from the test centre for that to happen.

Leonard Hofstadter

coylemj wrote: »

Spending €400 on a 15 year old Corolla is total nuts. Proves the point that giving your car to a garage for a pre-NCT service & check is as good as giving them a blank cheque.

I drive mainly around town on short journeys but about every other week when the engine is up to operating temperature I give her a blast up to 5,000 RPM when it's safe to do so.

I disagree, why scrap a car that's working well? We're not Americans, we don't need to import their throwaway culture to be honest. Those cars are virtually unbreakable (in stark contrast to newer Toyotas I might add), so I see nothing wrong with shelling out that kind of money on a decent service, brakes, tyres etc on a car that is well capable of lasting a good few more years to be honest. Unless it was suffering from rust, I see no reason why that car can't live on for another while - the OP could spend a few grand on something newer and buy a total heap of crap that could need at least that kind of money, and more to get it through an NCT at some point. Few cars that are newer than that Corolla will be as trouble free no matter how well maintained they are.

-Corkie-

captainspeed wrote: »

I disagree, why scrap a car that's working well? We're not Americans, we don't need to import their throwaway culture to be honest. Those cars are virtually unbreakable (in stark contrast to newer Toyotas I might add), so I see nothing wrong with shelling out that kind of money on a decent service, brakes, tyres etc on a car that is well capable of lasting a good few more years to be honest. Unless it was suffering from rust, I see no reason why that car can't live on for another while - the OP could spend a few grand on something newer and buy a total heap of crap that could need at least that kind of money, and more to get it through an NCT at some point. Few cars that are newer than that Corolla will be as trouble free no matter how well maintained they are.

I think you missed his point there...:)

Leonard Hofstadter

-Corkie- wrote: »

I think you missed his point there...:)

Why yes, yes I did:o! Typical really:D!

coylemj

captainspeed wrote: »

I disagree, why scrap a car that's working well?

There is a fatal flaw in your logic - if it was 'working well' it wouldn't need €400 worth of work only to fail the NCT anyway.

Nissan doctor

What if it needed €400 worth of work regardless of the NCT? The NCT is not the only reason to have car repairs done.

Pottler

Nissan doctor wrote: »

What if it needed €400 worth of work regardless of the NCT? The NCT is not the only reason to have car repairs done.

Agree, also, €400 of repairs is really small beer - bash the colour coded electric wing mirror of a new car and you will part with far more just to repair that one thing. Try a modern diesels dmf or dpf replacement for eyewatering. I run an old 406 2.1td as a work hack - to get it the way I want it required €1200 of parts. Many will say that's nuts but it is economical, fast, comfy and now has fresh shocks, brakes, timing belt, is serviced, has 4 good tyres and everything works with no corrosion whatsoever. That or I could drop €600 a month on finance. I'd be sorting those emissions and going for the re-test on this Corolla.

Big Nasty

Nissan doctor wrote: »

What if it needed €400 worth of work regardless of the NCT? The NCT is not the only reason to have car repairs done.

Totally agreed but you would probably pick up a 97 Corolla with fresh test for that amount.

iPhone.

MCMLXXV wrote: »

Totally agreed but you would probably pick up a 97 Corolla with fresh test for that amount.

yep, but the way he went about it he knows what work was done, picking a 97 corolla with fresh nct is a good option too, but it could have passed the nct with bugger all done to it for the last two years, just out of luck.

120_Minutes

wow, just came back to post my HC's , i didnt expect this!

anyway, i usually service my car every year in jan/feb before the nct is due. i knew this year was gonna be big as to the way the car drove.

service
2 new tires
balancing
headlight focus
tracking
track rod arm replaced
bearing replaced
perished brake lines changed

400 quid.... thats not a yearly occourance.


....think i was gonna do an NCT without getting that done?

anyway the HC's are

low idle : 149ppm
high idle: 84ppm

friendface

Used Dipetane on my E46 diesel last time I went for the NCT. Great stuff. Smoke readings went from 3.900/m to 1.200/m (not sure what units these were measured in )

Seems to be that a lot of urban start/stop driving causes this increased buildup - half bottle of dipetane and some enthusiastic driving did the job. Good luck!

Nissan doctor

120_Minutes wrote: »

wow, just came back to post my HC's , i didnt expect this!

anyway, i usually service my car every year in jan/feb before the nct is due. i knew this year was gonna be big as to the way the car drove.

service
2 new tires
balancing
headlight focus
tracking
track rod arm replaced
bearing replaced
perished brake lines changed

400 quid.... thats not a yearly occourance.


....think i was gonna do an NCT without getting that done?

anyway the HC's are

low idle : 149ppm
high idle: 84ppm

High HC's are a sign of unburned fuel(misfire/poor combustion) or burning oil(valve stem seals normally on a corolla).

Leonard Hofstadter

I wouldn't have thought the HC emissions were that bad ND to be honest, the limit for high idle is 200 ppm, over twice what the HC emissions in that car are. I know the limit for low idle is supposed to be 0, but they normally just mark down 'N/A' for it and don't fail you for it (at least they didn't when I did the NCT some time back). That said, it wouldn't be unheard of for the valve stem seals to be gone, especially in a Corolla of that age.

I think myself it's a fuelling issue rather than a burning oil issue, becuase the lambda value suggested that it was running a little lean (1.02). When engines run lean that does tend to push up the HC emissions somewhat. Getting the lambda value back to exactly 1 should be enough to sort out the CO emissions anyway.

120_Minutes

Nissan doctor wrote: »

High HC's are a sign of unburned fuel(misfire/poor combustion) or burning oil(valve stem seals normally on a corolla).

I'm fairly sure shes not burning oil. as for the other, funny you should say that there is a regular sound (the only way i can describe it is a *put*) from the engine when its idling that is out of sync with the rest. everyone i've let hear it has said....ah sure its grand.

someone else said that urban start/stop driving can cause buildup. i have moved to the city inbetween NCT's and theres a lot more start/stop in the last year than ever before.

120_Minutes

GRRRR IT FAILED AGAIN!!!!

I dont understand this, here are the full figures for the first failure:

Engine/Oil temp: 85 C

Low Idle (960 rpm) CO .18 % HC 148 ppm - PASS
High Idle (3050 rpm) lambda: 1.02 CO .39% HC 84 ppm - FAIL

and today:

Engine/Oil temp 110 C (notice its higher)

Low Idle (810 rpm, notice its lower) CO .29% (notice its higher???) 136ppm - PASS

High Idle(2870 rpm, again lower) Lambda: 1.02 (the same) CO .36% HC 68ppm - FAIL

This is with half a bottle of Dipthane in it since the last test. what the hell do i do?

Senna

Did you add the Dipthane to a full tank, use it all up and refil it again or would there have been Dipthane in the tank at the time of the test?

120_Minutes

Senna wrote: »

Did you add the Dipthane to a full tank, use it all up and refil it again or would there have been Dipthane in the tank at the time of the test?

added a quarter bottle last week after a fill up. and same again this week.

Cosmo K

So you used Dipetane and your car still failed?! Surprise, surprise.....not!

120_Minutes

Cosmo K wrote: »

So you used Dipetane and your car still failed?! Surprise, surprise.....not!

what would you recommend then oh wise one?

ongarite

120_Minutes wrote: »

what would you recommend then oh wise one?

I think he would recommend bringing the car to a competent mechanic and get a proper assessment and diagnostics of the NCT fail rather than just throwing in dipthane and "sure that'll fix it right up"

Organic Cavity

Or putting diptane in a half tank.

Nissan doctor

120_Minutes wrote: »

what would you recommend then oh wise one?

Diptane does not repair faults.

If your car has still failed then you need to have the problem diagnosed and repaired.

Leonard Hofstadter

Dipthane is not really that useful for petrol engines to be honest. The engine is still running lean (lambda is 1.02 instead of 1) - that needs to be corrected. That's why it's failing, and will continue to fail until that is addressed. Since it's not really out all that much, it suggests that it could be a very slight air leak of some description, perhaps a hole in the exhaust, but I'm no expert. This could be the one case where changing the cat might be enough to get it through, since everything else is more or less in spec, but again others would know better than me on that score.

C4Kid

How do they gauge the Engine Oil temperature ?