The web-site not seems to work so I hope the Mods would not mind me using the BR to call for Andrew or Adam.
Would you kindly send me an email to
garrison_tsang"at"lycos.co.uk
please?
My Nissan QX was high in CO though managed to passed its MoT in Apr after much revving. I have had the car "sniffed" again in Aug and CO is still high, though within MoT limit. HC is very low, sometimes below 10. I suspect sensors are at fault and want an expert opinion, before I changed all the sensors and the cat.
Thank you very much.
|
Gazza
Can you post up all the numbers from the print-out?
|
First attempt:
Fast Idle @ 3000rpm:
CO = 0.25-1.2%
HC = 20ppm
Lambda = 0.93-1.17
Natural idle @ 675rpm:
CO = 0.35-3.2%
Fifth attempt:
Fast Idle @ 3000rpm:
CO = 0.20-1.0%
HC = 16ppm
Lambda = 0.95-1.12
Natural idle @ 675rpm:
CO = 0.30-2.9%
Between each attempt, I drove around the block at 5-6000 rpm in first gear, totalling 30 seconds. CO and Lambda values both fluctuate, so the emission is within MoT limits for a short duration.
The question is why would the CO and Lambda fluctuate? My old Mondeo does not fluctuate that much and even then the fluctuation falls within the MoT limits. To give an example, the old Mondeo gives HC<30ppm, CO<0.05% and Lambda is stable at 1.002.
|
Well, you can check the obvious (like no air leaks into the inlet manifold) but I would say that you have duff lambda sensor(s).
Check the output with a DVM (or one of those lambda testers that ECP sell for about £17). If you see it is sluggish then replacement is the only answer.
|
Sorry, just finishing my cuppa!
Agree with Aprilia, sounds like an iffy O2 sensor.A quick check is to hold the revs at 2500 or 3000 with your foot steady on the pedal (trick is to put your left foot under the pedal and press pedal against it) and watch the rev counter. A 'slow' or 'lazy' sensor will cause the revs to rise and fall by a couple of hundred either way as the sensor slowly changes from rich to lean. Not impressed with 'universal' sensors, I prefer to use oe where possible or failing that a Bosch or Lucas specific fit replacement.
Sorry our website is still awol, I have paid the bill, honest!
Andrew
--
Simplicate and add lightness!!
|
|
I have also found that you can 'feel' a slow sensor when cruising at steady speed (say 40mph on a flat road). You can actually feel engine output fluctuating with the rich/lean switching.
|
|
|
