Very High CO% at idle

[fizban]

Hi all,
My car failed MOT due to very high idle CO%  (2%~)
All other emissions were ok, as well as the 2500rpm cruise tests of 4 gasses.
What are the main causes for high CO% at idle?
I am running a bit rich (0.99/0.98) at idle. 
Do you think this is the cause for such a high CO%?

Thanks

[Sprocket]

It depends on what engine, how old and whether a cat should be present as to what test is being carried out at the time, but it sounds like you need to tune idle areas of the maps to achieve lambda 1.00.

Generally, fuel injected engines should have Lambda 1.00 all the way up to cruse, maybe 40 or 50% throttle, and across to around 4 or 4.5k rpm depending on actual speed at cruse. This keeps the cat working. all other areas should start to richen up as rpm increase and as throttle widens.

It is not usually an issue if the Lambda map is tuned for lambda 1.00, and EGOC is turned on, unless idle is erratic.

My MOT tester was amazed at the emissions results on my Mini, an older car that had emissions limits for a carb engine lol. Sailed through


Oh, and ~2% CO is not very high at all, The Mini would still pass at that 6% at idle and i'd be worried

[rob@vems.co.uk]

I had this with an RS Turbo, and have heard of it on other cars.
You will need to mess around with your fuel injection sequence - its most likely injecting when the inlet valve is open - at low engine speed you don't get the homogenization you need.  Moving the injector table sequence may sort things.

Have you got a recent ECU?  Are you running cam sync?  If not is it an option? You should be able to spin the timing round to the point that the sweet spot for emissions has been hit.

[fizban]

Thanks for the replies.
The vehicle is 1998 model and has a cat. the cat is 100 cells.
Engine is not that old, done 40K kms, but pistons and rods were changed to turbo ones. C/R is 8.3:1 and the car has a GT28RS turbo.
I tuned the idle lambda to 1.0 again. Maybe because the RPM is 950, CO% is higher?  Anyway, the car was ok in the 2500rpm test.

I have an old ECU, 1843. And also on my win 7,  vems crashes when i enter, injector outputs visual. How do i move the injector table, if not there? I will check the cam-sync option.

[fizban]

Can I simply alternate the injector bank order?  In the injector settings (alternate banks from[h0])?
I use a double coil pack. Fuel divider is 2.
Probably the be map will need retuning as well?