% CO to AFR

[BillWilliams]

The tii manual says the tii idle CO should be 2-3 percent. What is that in AFR terms?

[c.d.iesel]

Hi Bill - about 13.5

and this

... from the extensive Special Tool thread

go to this link for a chart

http://www.mgexperience.net/article/co-afr.html

[BillWilliams]

so 13.3 - 13.7?

[c.d.iesel]

yes sir.

but another important goal whan adjusting idle mixture is

adjusting the Co% so that you have the lowest HC ppm reading.

The HC ppm reading raises with with too lean

or too rich - on each side of the optimun middle

so 2% Co might cause a lean misfire and high HC ppm reading

and 3.5% Co might cause excessive rich idle and also high HC ppm

reading. So probably 2.75% Co would give the lowest HC ppm

reading. HC is unburned hydrocarbon - BAD

Having a vacuum gauge T 'd into the booster hose

will also agree with the lowest HC ppm reading.

Optimum idle mixture adjustment will result in the highest

idle vacuum reading (approx 22 ...24 in.)

Now when you come off of idle - thats another story......

[BillWilliams]

Thank you, I have some tunin' to do!

[bnam]

Great! Just the question I was about to ask -- now that I've got my WB02 installed (though not working correctly yet).

Just copied the info from the MG link.

Byas

[flyingjolly]

Hi Bill - about 13.5

and this

... from the extensive Special Tool thread

go to this link for a chart

http://www.mgexperience.net/article/co-afr.html

awesome! Thanks!

[Guest Anonymous]

Bill W. im currently tuning the A4 system. What do you recomended % CO to AFR for the system? TIA

[BillWilliams]

I would say it should be what a stock tii would be.