Idle AFR Swinging Rich to Lean

[gtx3076]

I took a log to send to Dizzy but my AFRs sometimes swing from the 13's to the 15's while idling, A/C off. I'm tuned in E30 and am running step colder spark plugs. AFRs make me think maybe an 02 sensor. Car has 100k miles and is 5 years old.

It's not all the time, just intermittently, other times AFR's stay in the 14's at idle like I'd expect. Anybody else experience something like this?

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[Se7eN]

I took a log to send to Dizzy but my AFRs sometimes swing from the 13's to the 15's while idling, A/C off. I'm tuned in E30 and am running step colder spark plugs. AFRs make me think maybe an 02 sensor. Car has 100k miles and is 5 years old.

It's not all the time, just intermittently, other times AFR's stay in the 14's at idle like I'd expect. Anybody else experience something like this?

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All the time, even from new. Mostly after filling up with gas, or if it's been on for a while. Doesn't affect anything.

 

[DieselMech]

Same here, happens every now and then. Ac cycling on an off puts a load on the engine that could be doing it even pressing the clutch in and out. Doesn't hurt anything.

 

[SlowDunny]

bad evap purge valve, I changed mine and it went away.

It will probably come back when this one fails.

Buy the one that comes with the hoses.

 

[gtx3076]

bad evap purge valve, I changed mine and it went away.

It will probably come back when this one fails.

Buy the one that comes with the hoses.

Is that why I smell gasoline in the car after I fill up?

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[SlowDunny]

Is that why I smell gasoline in the car after I fill up?

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Most likely but you may have another issues with your fuel evap system. I started with my purge valve because it was classic symptoms of it (stumbling after fill ups).