Advice needed - How to adjust CO level at idle

[moscowphil]

Hoping someone can give me few ideas how to do this. I'm in the process of re-registering my Scura onto Spanish plates which is causing me a few problems - As part of the process I have to get the bike through a sort of extended MOT test (called an ITV), but it failed on the level of CO emissions (which are tested at idle). My bike was producing 5.5% CO, where the limit in Spain is 4.5% - so an automatic fail. 

So I need to sort this out pronto. I'll give the bike a full service, including  new plugs and air filter,  check the TPS voltage and check the engine and air temperature sensors are working, which hopefully might sort it out, but is there anything else I can do to lean out the mixture at idle? (I assume leaner mixture = less CO). I've got a PC3 fitted (with a null map at the moment, as it's back on its standard exhaust for obvious reasons) - if I just use this to lean out the bottom range would do this do the trick? Or is there some other way of adjusting the idle mixture?  

 

The bike is going great, so I can't imagine there is anything seriously wrong anywhere, and I don't want to change anything drastically, but I've got to find a way of getting it through the test!

 

Any advice? Thanks 

[docc]

The CO is adjusted digitally through a computer interface (Moto Guzzi Axone, VDSTS, or Guzzidiag, etc)

 

Once you find the CO trim n the software, note its numerical position. You can then reset it to a value that should carry through the testing and put it back where you like it when finished.

 

Check out the Guzzidiag thread here.

[luhbo]

As you already have the PCIII I think you should try this first instead of anything else. I don't know whether you can make changes while the engine is running, but this would make things quite easy. Just lean out the lowest 3x3 or maybe 4x4 cells until the rpms beginn to fall. Then compensate this by slightly opening the bypass screws.
When you repeat the CO test you should know that after starting the engine the ECU enriches the mixture for approx. 1000 revolutions. Holding the engine at higher revs for 1 minute before you start the sniffer might look a bit strange, but it will certainly help.

 

Hubert

[moscowphil]

As you already have the PCIII I think you should try this first instead of anything else. I don't know whether you can make changes while the engine is running, but this would make things quite easy. Just lean out the lowest 3x3 or maybe 4x4 cells until the rpms beginn to fall. Then compensate this by slightly opening the bypass screws.

When you repeat the CO test you should know that after starting the engine the ECU enriches the mixture for approx. 1000 revolutions. Holding the engine at higher revs for 1 minute before you start the sniffer might look a bit strange, but it will certainly help.

 

Hubert

Thanks Luhbo, that's brilliant information. Particularly the bit about the ECU enrichening the mixture for 1000 revs after startup, which I didn't know. The tester checked the emissions immediately after I restarted the engine, so it could be that this is the only reason it failed! But I will also try leaning it out a bit with the PC3 to be on the safe side. I can always put it back to where it was as soon as I've left the testing station!

Phil

[luhbo]

I hope this will do the trick. Can't you check it yourself at the next car shop? In case it's just the starting enrichment I would leave the ECU alone. The engine should be hot when you check the CO, a head temperature of 80°C will help (if CO still is critical).

 

But, as I never had this problem, I never really proofed what I wrote above.

 

Hubert

[Meinolf]

... the ECU enriches the mixture for approx. 1000 revolutions...

 

Hi,

 

the standard value is 3984 revolutions, not 1000. But, the influence of the start enrichment (standard map) is almost nil at normal ambient temperatures and it decays rapidly after several hundred revolutions.

 

https://db.tt/SOJiFgSL

 

Use the CO trim function in GuzziDiag to pass the test and set it back to the original value afterwards.

 

Cheers

Meinolf