Emissions

Level 6 User Joined: 10 Nov 2005 Posts: 149

My 19 16v just had its MOT today and passed.. Smile

however, the guy pointed out that the CO level took a while to settle below the required level (<0.5% i think?) after going back to idle and that it could be the oxygen sensor being "slow" (ie. something is not as it should be).. i know that CO levels will be high when the car is running rich, since then theres no oxygen to oxidise the CO to CO2.. so the question is, if there is a good possibility that its the oxygen sensor acting up or is the 16v supposed to be like this? i never MOT'ed a 16v before, so i can't say what other MOT ppl say about this.. the car has a cat btw...

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

whats the lambda reading?

Whats the co reading?

What was the engine temp?

When was it last serviced?

Level 6 User Joined: 10 Nov 2005 Posts: 149

engine was warm/hot.. dunno exact temp, since theres no readout for that..

lambda reading was between 0.990 and 1.009 during the test iirc..
the highest CO value i saw was 5%, but when it settled, it was around 0.25-0.30% i think..

they dont give you a report over the readings, so this is as good as i remember it..

what do you mean by "serviced" ? at renault for a regular service? i don't know.. (i usually change fluids and wearing parts myself)

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

engine temp shoudl have oil temp 80 degree nmin or will say temp gauge at normal op temp.

so it was cycling up and down on the lambda?

Whats the car used for,.

Serviced, filters, fluids and plugs changed.

Amazing how far the co and hc's can drop when theres fresh oil in an engine.

Level 6 User Joined: 10 Nov 2005 Posts: 149

Chris H";p="99915 wrote:

engine temp shoudl have oil temp 80 degree nmin or will say temp gauge at normal op temp.

????

Quote:

so it was cycling up and down on the lambda?

wouldnt call it cycling, but these were the extreme values i saw..

Quote:

Whats the car used for,.

daily driver

Quote:

Serviced, filters, fluids and plugs changed.

coolant, oil, oil filter and air filter are new. plugs i dont know.

it was on a dyno 2 months ago and i would say the graphs shows a healthy engine, even if the absolute max values were a bit optimistic..

afaik, lambda is open loop when working the throttle, which would mean that the converter does not get the optimum mix for oxidicing/reducing, is this correct? was just wondering if the MOT guy's wrong in being concerned with something that took like 10 secs to settle after letting off the throttle.. when keeping constant throttle, everything looked fine.. is the CO value supposed to be constant no matter if you rev it or not? and how quick must it settle?

i may be far fetched here, but since the subject interests me, i'd like to know what's going on and how the stuff works .. Smile

cheers..

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

its nto a problem the fatc that it passed is enough.

But the fact irts cyclign then the lambda's either coked up or needs replacement. if you pull it out and blowtorchit you can bring them back to life.

Its only open loop above a certain rpm and throttle angle.

Level 6 User Joined: 10 Nov 2005 Posts: 149

i will try the blow torch then i think.. not that i have an emissions tester at hand, though.. are there any guidelines for how much heat and so on the sensor needs/can cope with safely?

cheers..

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

more heat than the blow torch can vgive out thats for damn sure! lol

Anyway pull the sensor out and heat it with sa blow torch until cherry red.

Wear eye protectiona dn gloves. The outer dome shaped shell will make the carbon/rust splinter off, it does thise with a ping, so you need to watch yourself.

if you have a multimeter, set it to mV, using tyhe blowtorch and the meter in the black signal wire and the other one stuck to the sensors body pass the blowtorch back and forth across it, when you have cleaned it up with the blowtorch it shoudl repsondf pretty much instantly.