[cam765]

I have an AEM 30-0334 wideband installed on my driver-side high flow cat connection pipe, after the headers. When driving, my A/F ratios look good, right around 14.7:1 and drop during WOT. However when coasting, it drops momentarily to 13:1 or 12:1, and then shoots up past 20:1 and onward until it doesn't display a reading (only dashes). When I give it light throttle, it immediately returns to a good reading. Thoughts?

[Replica]

A wideband reading like that is perfectly normal as when you coast, there is a small bit of fuel injected for a second after letting off the gas, called overrun.

Then it will transition to literally injecting no fuel as it is not needed for deceleration.

This is why it is more fuel efficient to stay in gear downhill than to go to neutral, because in neutral the engine must still combust fuel to stay running.

[cjperformance]

Originally Posted by Replica

A wideband reading like that is perfectly normal as when you coast, there is a small bit of fuel injected for a second after letting off the gas, called overrun.

Then it will transition to literally injecting no fuel as it is not needed for deceleration.

This is why it is more fuel efficient to stay in gear downhill than to go to neutral, because in neutral the engine must still combust fuel to stay running.

Plus the cool kids talk lamba instead of AFR these days.