Another emissions failure :(

[karol_SVK]

Hi, i just read the recent thread about MOT failure, but decided to make a new since my readings were totally out, like on a Boeing 747..

on idle:
CO - 5.604% (limit is 0.5)
HC - 860ppm (limit is 100)

at revs 2500-2800:
CO - 6.64% (limit 0.3)

lambda:
0.876 (should be 097-1.03)
also the idle was on 800-810rpm

Prior to the test i drove 4km, then had a break, idled 10 mins, got back 4km with normal tempo, so It might be just not warmed up properly.
I had a DF057 Upstream sensor circuit error in the history so might the lambda just be lazy with age (i am not avare of a change)
After the test fail i went to give it some beans and when parked up in the garage home i did not smell any petrol, HC from exhaust.
I have around 35 mpg when calculated from fuelling and the car drives fine. I have replaced the exhaust for a genuine one few months back. CAT is on, maybe still the one it came from factory.

I am just not sure if change the lambda (as i had some lambda related errors / df057) or just try ones more the MOT with proper 20miles usage of the whole rev range, as the figures I had were totally out and she starts fine, usually wait a minute, then drives fine. I did not change sparkplugs in the last 2 years, but i drove only 8827km as its a weekend car for me.
Upstream Oxygen sensor is the PRE-CAT? Hard to replace?

Some pictures from CLIP:
idle after 2hrs of pause (was charging laptop) - 1m55s
http://imageshack.us/photo/my-images/209/8gvz.jpg/

idle after warmed up short - 23s
http://imageshack.us/photo/my-images/845/in17.jpg/

running warmed:
http://imageshack.us/photo/my-images/69/ewjx.jpg/

ECU get values in good interval, so might just the lambda do wrong readings.
I did a few theory reading how the lambda works, but why does the value have to be 0.97-1.03, if values close to one are for a rich mixture?

Thanks for any ideas, inputs.

 

[Dan@SJM]

Sounds like upstream lambda. I haven't looked at the pics however (on GPRS signal here)

 

[karol_SVK]

Upstream is the one pre-cat?

I assume yes, because from the upstream lambda i get data sooner than from downstream which gets to heat up later. But I am not sure

 

[karol_SVK]

Hi guys, another question in my research...

My dephaser pulley is letting me know its there...MOT guy opened bonnet and asked...is it a diesel?
There is a power increase around 5k rpm so i assume VVT is in tact.

Can a rattling dephaser pulley take part in high emisions?

 

[Dan@SJM]

It can do, but not by that amount.

Have you changed the lambda sensor yet?

 

[karol_SVK]

Not yet, I will go to MOT station on Wednesday with a properly warmed up engine and see the results. If its still bad, then I change the lambda and sparkplugs.

Yesterday i went to a drive and just noticed that the upstream oxygen sensor values where oscilating like they should, but the downstream was getting lower and lower when driving (thus warmimg more up), and getting higher when stopped and on idle (cooling down).

 

[karol_SVK]

Changed the Oxygen sensor yesterday.
If feels different. When starting from cold in the morning, the revs fall down much quicker, and drives better on cold. Maybe idle is a bit lower on warm engine too.
I will put it on PC today if I can see a difference in the curves (lambda).

I forgot some documents needed to the MOT, so I will have to go tommorow

 

[karol_SVK]

So I was at MOT today after Oxygen sensor change, emission were fine

Lambda 0.999
HC = 55
CO = 0.3

Even mamaged to get 5,9L/100 km (56mpg) till i got stuck in traffic

Here is some knowledge picture and translation:

bohata = rich
chuda = lean
0,5 = target value