HEGOs on Cold Start

[auscob07]

How long after a cold start do HEGOs start reporting reliable data? My tune is in OL until around 100s so not required until then but just wondering if and how accurately they report in the first, say 10s, 30s, 100s, 250s?

In a cold start log, they seem to ramp up from lean to rich for about 40s then hang around being rich until CL when they start oscillating between the two. Just wondering if this is actually going from lean to rich or are the HEGOs going through some warm up procedure where the data is meaningless.

[decipha]

read the hego write up

[auscob07]

Just re read that but there is no mention of any start up procedure and what that entails - particularly in the GUFX strategy. Also, when cold, is it just the time it takes to switch that is affected, or is accuracy impacted as well.

[decipha]

cold hegos switch slowly if you go in to closed loop too soon a cold hego will swing fuel around

the farther back from the engine the hego is usually the longer it takes to warm up

hegos are voltage generators they cannot report rich unless its rich except in cases where the heating element is shorting

if the hegos are reporting full rich 0.800 volts or so then they are probably warmed up enough ymto control fuel

[auscob07]

Thank you, I think this answers my query.

if the hegos are reporting full rich 0.800 volts or so then they are probably warmed up enough ymto control fuel

Mine start switching soon after they scroll up from lean to full rich.

Cheers