2000 Nissan Almera, High emissions at low idle?

razz

Hi

Recently I had my car in for an NCT and it has been failed on high emissions at low idle!
I have had the M.A.F sensor changer and the throttle body cleaned as a friend reccommended it.....but still i have been failed again for the same reason..

I have brought the car to a local garage who said they do not know what is wrong with it, as the CAT and Lambda sensor seem to be working fine?????

I was just wondering did anyone else have this trouble?? or can they help me out with what they think could be wrong please???

here are the NCT readings:

engine oil temperature:86 degrees celsius

Low idle: CO 4.91% ABOVE 0.50% FAIL
(800 rpm) HC 213 ppm ABOVE 0 ppm N/A

High idle: Lambda = 1.01 NOT BETWEEN 0.97 AND 1.03 PASS
(3,050 rpm) CO 0.03 vol% ABOVE 0.30% PASS
HC 43 ppm ABOVE 200 ppm PASS

Waterson

The engine is running very rich at idle. Start by checking the very basics: condition of air filter and inlet tract for blockages, splits in vacuum hoses, operation of fuel pressure regulator on fuel rail. Is the car misfiring at all and what is its power output like? A poorly funcrioning lambda sensor could be the issue as that system is in a closed loop at idle and would have a significant bearing on fuel trim.

razz

Waterson wrote: »

The engine is running very rich at idle. Start by checking the very basics: condition of air filter and inlet tract for blockages, splits in vacuum hoses, operation of fuel pressure regulator on fuel rail. Is the car misfiring at all and what is its power output like? A poorly funcrioning lambda sensor could be the issue as that system is in a closed loop at idle and would have a significant bearing on fuel trim.

Sometimes it's a bit hard to start! Then may cut out straight away! But then with another turn of the key and a little acceleration and it's ok! Slight loss of rpm when coming to a stop also!????

TBi

We had a problem with a same era Micra. The oil temperature sensor had gone bad with age. It thought the car was at -20C when it was 10C out. Although it would usually come right when the car warmed up. Made it hard to start but would start with a bit of accelerator. Got worse with time.

Might be something to consider. Not the same engine but could be similar issue. BTW the thermostat which gives the engine temperature on the gauge is a different sensor.

Waterson

razz wrote: »

Sometimes it's a bit hard to start! Then may cut out straight away! But then with another turn of the key and a little acceleration and it's ok! Slight loss of rpm when coming to a stop also!????

Without additional data its hard to say, but the hard start could be a symptom of the overly rich long term fuel trim, simply that the engine is running on too much fuel either in response to a lean condition (unmetered air is entering the engine/fault in fuel system) or to a malfunctioning oxygen sensor itself. Could be a number of things. A competent mechanic should be able to diagnose the issue.

razz

Finally got my car trough the NCT, after having it with 2 garages who said they where not 100% certain of what was causing the problem but wanted to change the CAT and lambda sensor etc! Basically wanted to throw new parts into it until the problem was fixed! 👎😞
I decided to go with a final opinion and as with being busy with work and the NCT deadline approaching I found a mobile mechanic who came to me! found the exact fault!
End up being a solenoid!
He got 1 for me from a scrap yard and fit it for me
Went trough the NCT with ease! 😊
Cost me €60 instead of the other quotes of €400 - €700😳😳

HIGHLY RECOMMEND THEM😊😊😊