NCT Failure. How Do I Lower My Emissions?

Phoole

Hi guys,

My car passed it's NCT 4 weeks ago, the day before I bought it. As I will be using the car as a taxi, I had to do a re-test for suitability. But this time it failed on the Lambda reading.

Here's the Two Seperate NCT Reports. 4 weeks apart.

Sept 12 2007
Temp: 79 C
Low Idle: (860 rpm)
CO 0.00 vol%
HC 0 ppm

High Idle: (3090 rpm)
Lambda: 1.019
CO 0.00 vol%
HC 16 ppm

October 11 2007
Temp: 100 C
Low Idle: (880 rpm)
CO 0.00 vol%
HC 0 ppm

High Idle: (2860 rpm)
Lambda: 1.053
CO 0.00 vol%
HC 8 ppm

Lambda Range = .097 - 1.03

Any clues here?

The car has been sitting in the driveway since I bought it (driven only 150 miles). I'm wondering if a cold unused engine would have had anything to do with it's higher emissions on the day. Or is there any other trade tricks to lowering the emissions for the re-test?

Thanks in advance

Rob

Hagar

A cold engine would be a no-no. Get the engine well warmed up so that it is operating at it's most efficient. A good fast run down the local dual-carriageway should do the trick, burn off some of the carbon deposits that build-up in stop-start city driving.

Also there are there fuel additives available in Car Shops that supposedly remove carbon build-ups etc. from the engine? If these were any way effective I'm sure they would help a little. Or have I just revealed my gullibility?

Head The Wall

Removed my Lambda sensor, soaked it in lemon juice overnight and cleaned it afterwards. Worked for my car

Phoole

Head The Wall wrote: »

Removed my Lambda sensor, soaked it in lemon juice overnight and cleaned it afterwards. Worked for my car

I like the sound of that. Where is it and how do I get it out?

cantdecide

I had a workmate with a rav4 and it was a lottery with the NCT. Sometimes emmisions wereup, then down, then up , then down. Never resolved it in the end but it was probably a lambda. When I had one changed in a 325 i had, running and fuel consumption was intermittantly poor/ good/ poor/ good...

Head The Wall

Depends on your car, you need a lambda tool to get it out also. Probably a job for a mechanic

Phoole

Here's the Two Seperate NCT Reports. 4 weeks apart.

Sept 12 2007
Temp: 79 C
Low Idle: (860 rpm) CO 0.00 vol% HC 0 ppm
High Idle: (3090 rpm) Lambda: 1.019 CO 0.00 vol% HC 16 ppm

October 11 2007
Temp: 100 C
Low Idle: (880 rpm) CO 0.00 vol% HC 0 ppm
High Idle: (2860 rpm) Lambda: 1.053 CO 0.00 vol% HC 8 ppm

Lambda Range = .097 - 1.03

Any clues here?

Hagar

I wonder what results you would have gotten from an NCT test the day you bought it?

Call me a cynic but am I the only one who has doubts about the NCT test results issued to the trade?

BrianD3

Lambda: 1.053

Could well be due to a hole in the exhaust.

Mike...

A good run in 2nd or third gear for about 5 - 10 miles at 50-60mph seems to do the tricks...removes all the muck from the engine

Phoole

BrianD3 wrote: »

Could well be due to a hole in the exhaust.

Had the exhaust checked out yesterday. No problems there. I just find it astonishing that merely 150 miles later, that the Lambda reading has gone up that high.

Cosmo K

Definitely a leak in the exhaust system. What type of car is it?

pwee

In your first test temp was 79c

Now 100c in 2nd. Thats a big dif.

How was it so hot for the second test?

IMO the test results the first time are not for your car. Did you buy it of a dealer?

Melion

My NCT was something like that the first time i put it through. I put in Shell VPower the day before and drove the arse out of the car. Driving into the centre i drove in only 3rd and 4th gear, never went into fifth. It cleared everything out and i passed.

Captain Slow IRL

The high lambda value means there's an excess of oxygen passing through the exhaust - this could be a leak in the exhaust or the air intake system (after the mass-air flow meter)
Your lambda probe could also be at fault, as previously suggested - bring it to a reputable garage, they will be able to diagnose it

wil

Hagar wrote: »

A cold engine would be a no-no. Get the engine well warmed up so that it is operating at it's most efficient. A good fast run down the local dual-carriageway should do the trick, burn off some of the carbon deposits that build-up in stop-start city driving.

Also there are there fuel additives available in Car Shops that supposedly remove carbon build-ups etc. from the engine? If these were any way effective I'm sure they would help a little. Or have I just revealed my gullibility?

As H said taking car for good spin, 100 miles or so to get the crap out.
Second, I'd always keep the engine hot before handing in for NCT. Its not going to get adequately warmed up in the first few minutes when they do the test if you have been sitting waiting for an hour.
Most of the the additives are probably a waste of money, or so Ive been (gullibly) told but my mechanic recommends only one that works, costs about 50 a throw, cant remember name offhand. As my car flew* through without any work on emissions, not even a new sparkplug, he could be right. It takes 100miles or so to be effective.
(*Alternatively soak in Red Bull )
*Dont do this please

green123

Hagar wrote: »

Call me a cynic but am I the only one who has doubts about the NCT test results issued to the trade?

the motor trade is full of gangsters and cowboys,
so i would also have my doubts

Phoole

Thanks for all the suggestions guys. I'm taking it for a diagnostics test tomorrow. I hope that'll help. Gonna bring it for a long hard drive before my re-test also.