A/F gauge freaks out in mornings

[LegacyPunk]

so....recently when ive started my car in the mornings my air fuel gauge kinda freakes out and all the LED's flicker at the same time, it then goes away after a while. Im just wondering is this could be a sign of a failing O2 sensor or something else? or is this just part of the "Millenium Falcon Syndrom"?

[Brat4by4]

Your o2 sensor tells you absolutely nothing until it gets to something like 1100 degrees. So ignore it, your car does.

[vrg3]

All the LEDs flicker at the same time? Normally only one LED is on at a time, right?

How cold are your mornings? Most of these "air/fuel ratio gauges" are based on cheap consumer-grade LM3914 chips that are only rated down to 32 degrees Fahrenheit.

[LegacyPunk]

not that cold yet, I was just wondering if it was a cause for any concern. All of them flickers a tiny bit for a while untill I drive around a bit, might just be a connection thing. Im not too woried about it.

[Nigel]

Mine will do that too from time to time. But it's quite rare. Maybe it's condensation causing some electrical noise.

I have a question for you (or for anybody else who cares to reply) related to your A/F gauge. When you accelerate hard enough to reach positive manifold pressure (boost), does your gauge immediately show rich? Or does it continue to bounce back and forth like the ECU is still in closed loop mode? In my Legacy, quite frequently, I can be making 5psi or more of boost, and the A/F guage responds like the ECU is still in closed loop mode. Furthermore, I can feel the engine hesitating in time to the fluctuations on the gauge. I think my manifold pressure sensor is flakey and it's not telling the ECU when the engine is making boost sometimes. But I don't know what the proper response from the ECU is supposed to be to boost. Is it immediately supposed to go to open loop mode, or is there some other parameter combined with the MAP sensor before it will go into open-loop.

I hope I'm not hi-jacking your post.

Nigel
'94 Legacy Turbo

[vrg3]

Nigel, are you using stock boost control? I sometimes see similar effects when not using stock boost control. My guess is that the ECU wasn't designed with the idea of boost at small throttle angles in mind.

[The Scooby]

its because your car runs in closed look, meaning ignoring your O2 until the O2 reaches 600 degrees, then once it is at that temp it switches back to open loop. so its ok, nothing to worry about.