[schoward]

Peter, Thanks for the response.

Yes - Think I did pretty much that procedure using my Gunson. CO in range 0.6-0.8 at cat test port; O2 unplugged ; at operating temp and in-range idle.

But Dwell on ECU test port indicates slightly lean setting in closed-loop operation. Reading of dithering 55-60% closed-loop duty cycle vs. around 50% per the Bosch repair book which has me questioning.

At proper CO spec, I would have expected dithering around 50% duty cycle unless my Gunson wrong, OR that's what the stock CO idle spec yields by design - slightly lean and O2 corrects it (perhaps for emissions?)..

Disregard the dwell reading? Disregard the Gunson?

Thanks.