www.gt4dc.co.uk
http://www.gt4dc.co.uk/forum/

Failing MOT emissions, CO high - what to adjust in mapping?
http://www.gt4dc.co.uk/forum/viewtopic.php?f=13&t=6368		 Page 2 of 2
Author:  Diceman [ Thu Mar 07, 2013 10:57 pm ]
Post subject:  Re: Failing MOT emissions, CO high - what to adjust in mappi
the pot of gas is a bad lead - I used it to check datalogit vs wideband output values tallied (very slowly and constant changing AFR as the gas leaked out!

I can't help thinking that the lambda sensor is reading the wrong info. High CO and High Lambda point at two different scenarios.

I can only think iof 2 sensible options
1) fooobarred O2 sensor
2) air leak in exhaust meaning sensor is reading lean when it is richer during combustion.

The third thing that I am not sure about is what woudl happen if you had a very lean mixture causing an occasional miss-fire? In my head this gives a rich reading but is lean.
Author:  Nibbles [ Fri Mar 08, 2013 10:59 am ]
Post subject:  Re: Failing MOT emissions, CO high - what to adjust in mappi
I forgot about exhaust leak, mine failed on lambda error while running standard ecu. In my case engine was running fine co ok but lambda at tailpipe read high.
Author:  Dan [ Fri Mar 08, 2013 11:31 am ]
Post subject:  Re: Failing MOT emissions, CO high - what to adjust in mappi
Diceman wrote:
the pot of gas is a bad lead - I used it to check datalogit vs wideband output values tallied (very slowly and constant changing AFR as the gas leaked out!

I can't help thinking that the lambda sensor is reading the wrong info. High CO and High Lambda point at two different scenarios.

I can only think iof 2 sensible options
1) fooobarred O2 sensor
2) air leak in exhaust meaning sensor is reading lean when it is richer during combustion.

The third thing that I am not sure about is what woudl happen if you had a very lean mixture causing an occasional miss-fire? In my head this gives a rich reading but is lean.


New O2 sensor is on the way.

I'll have a poke about underneath it over the weekend and see if any air is leaking in post-sensor as that did occur to me as well.

There is an occasional burbly misfire when doing the fast idle test, so I'll chuck a new set of plugs in it, and fit the new rocker cover gasket as well.

To be continued....... :lol:
Author:  two_OH_five [ Sat Mar 09, 2013 2:32 am ]
Post subject:  Re: Failing MOT emissions, CO high - what to adjust in mappi
Just a thought
It might be a misfire related issue. Lean with high HC would point to that but I don't know what effect unburned fuel would have on CO and HC isn't measured on idle

From Dagobah sent using the force this post was
Author:  Dan [ Sat Mar 09, 2013 9:10 am ]
Post subject:  Re: Failing MOT emissions, CO high - what to adjust in mappi
I'm not sure what was creating the misfire as the car runs fine on the road. It's just when trying to do the fast idle test there is a definite burble from the exhaust that suggests a misfire. However I'm at a bit of a loss as to what is causing the miss - it's possibly due to the closed loop O2 causing the engine to go overly rich and lean.
Author:  Nibbles [ Sat Mar 23, 2013 5:47 pm ]
Post subject:  Re: Failing MOT emissions, CO high - what to adjust in mappi
Did you resolve this in the end ?

Just had a freinds car fail on high Lamba (1.25 from memory) while CO was about midway - big blow at the rear joint. It is running far too well for the lambda to actually be that high.
Author:  Dan [ Tue Mar 26, 2013 5:35 pm ]
Post subject:  Re: Failing MOT emissions, CO high - what to adjust in mappi
Not yet Chris,

New plugs, rocker cover gasket and O2 sensor fitted on Sunday, and then I spent about an hour with the laptop plugged in and got the fuelling spot-on.

Once the snow vanishes I'll get underneath it and look for any blowing joints. Then I'll take it back to the garage and do an emissions test prior to booking it in for it's MOT.
Page 2 of 2 All times are UTC + 1 hour
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/