Idle spark advance

[vowler]

Hi.. I've been having problems meeting the emission requirements... max CO % here is 4.5.. mine was at about 5.6%.. so I went through the normal checks.. base timing, plugs, leads, air filter... then stupidly tinkered with the CO pot without realising how sensitive it is... screwed it in a few turns ( wrong way as it happens!! and surprise surprise new figure 9.2% !! anyway.. tried to get it back to an acceptable level with garage CO analyser in place but to no avail. Took out the CO pot and using ohmeter, found where the adjustment just begins ( 270 ohms ish ) and put it back. Then joined up elanscan just to have a look and saw the idle spark angle going anywhere from 10 to 20 degrees... Is this normal at idle? I happened to have a Hall sensor so changed that but no different.. the only thing I noticed was some radial movement ( about 5 maybe more degrees ) on the reluctor disc.. no up and down movement so I think the bearing is ok but the rotational play seems a bit excessive. I've attached the elanscan file.. I'd appreciate it if someone could look at it and offer advice!! Incidently, I havent been back yet to have the CO checked, so it may be ok... but I don't really want to go through all this aggro only for it to fail again. Any comments much appreciated...

[GeoffSmith]

Keith, it does look quite variable. I've checked a couple of good sets of idle data (mine and Paul Watkins) and the standard deviation is ~1.5° whereas yours is closer to 3°.

[vowler]

Thanks Geoff... I think I'll take it and get the CO tested tomorrow... maybe it'll pass... and Iwon't have to do anything else!!.... yeah maybe!!