DOES DIFFERENT OCTANE FUEL AFFECT THE CO?

[danny hoffman]

Just wondered if a lower octane fuel would affect the CO? Mine was a bit high at MOT time and I had last filled with Optimax (98 RON). Would filling with 95 RON have got me through if the tester wasn't so sympathetic? Any one with a CO tester done back to back checks with different fuels?

Danny

[redwedge5]

I only use optimax. Just had an MOT and the CO level was 1.63% vol which is well within the accepted limit. The engine is a 3.9l hot wire, I don't know whether this makes a difference.

[my 350i]

Different octane fuel wont make any difference to c/o content. What readings did you get?
Did it fail on just c/o or hydrocarbons as well?
Incorrect o2 readings can help point to posible problem areas as well
Dave

[Nickleby4]

Yes it will affect CO content!!! In order for it not to, you need to be running the much later closed loop efi systems which monitor, and adjust to co content (you find these on cars with cats). On a wedge you've a very basic quantative fuel system without lambda sensors.

The best advice is to choose a fuel type and stick to it. Once chosen have the car tuned. It's worth noting though that octane levels have fallen steadily since these cars were mapped, so if you've got a source of higher octane fuel.....

[danny hoffman]

I had given up getting a response on this! Any chance of someone with a tester doing back to back checks on different fuels?