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Discussion Starter #1
Hey everyone,

I've been told and read that when putting an a/f ratio gauge on the stock mr2 that it should bounce back and forth between rich and lean repeatedly. I've seen what it's supposed to look like on several other MR2's, and mine does this under load. However, when my car is at idle, it drops down so lean that I can't even see a reading at all until I rev or put the car under load again. I know that at idle my a/f gauge should still be bouncing, so what's the deal? something wrong with my o2 sensor or what? Thanks!
 

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if in closed loop your o2 sensor should be switching from rich to lean, those gaugse kindof suck tho so i highly doubt it can pick all that up fast enough.
 

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although expencive, wideband a/f gauges are actualy accurate, and you can actualy use them to tune the car, if it's not wideband it's not going ot be very accurate no matter what company makes it, the new product from AEM that has a wideband a/f computer built into a 2 1/16th gauge is the best product out there unless you are able to get a ems
 

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Discussion Starter #4
Okay can someone explain to me why my A/F ratio gauge doesn't bounce at idle like all the other Mr2 owners I know? I am well aware that the guage tells me essentially nothing but it came with my other gauge and its pretty expensive (autometer cobalt series, came with the boost gauge) so that's why I'm using it. And NC Turbo2, if I had the money for a wideband, trust me, I'd have one :)

I'm not so much worried about my car necessarily running lean or rich at idle or whatever, but I am worried that maybe my o2 sensor is going bad or something like that. I am just curious if this issue could be an indication that something is wrong.

Thanks for the replies so far.
 

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If you have a SAFC, make sure you have it wired correctly. My A/F gauge didn't respond properly because I had wired my SAFC in wrong.
 

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make sure the car is at operating temps cause the gauge wont read right. also, if you unpluged your battery during the install, it will take a few hours of driving to have the ecu relearn and go into loop mode at idle.
 

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Discussion Starter #7
Dougy, no SAFC. Thanks though!

lagos, I am aware of the o2 sensor needing to heat up. It doesn't read much at all when cold, but at operating temp, does what its done since the day I installed it.. works fine when there is load on the engine, but in neutral, it appears that I get so lean a reading that I can't see anything on the gauge. It just goes blank.
 

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Discussion Starter #8
can somebody please help me out with this? Or at least just verify that you get the "bounce" reading at idle too?
 

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Mine behaves the exact same way. (JDM gen 2 3sgte)
My friends civic's identical guage bounced at idle while mine doesnt, even after my car heats up (single wire o2).
I was very concerned at first and triple checked the wiring, and then swapped my guage with my friends civic's guage to prove that the guage works fine and it does.
Under normal driving my a/f guage behaves/oscillates as it should, but under idle it shows very lean.

Im not sure if thats normal for the 3sgte, im curious as well?
 
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I have a custom built DIY A/F-Meter with 20 LEDs, initially calibrated to 0-1 V what makes a sensitivity of 0.05 Volt per LED.
Idle: LEDs off = extremly lean
Midrange until ca. 3000 rpm: LEDs bouncing = closed loop operation
Load: 18-19 LEDs on (0.9-0.95 V) = extremly rich
Engine was at that time bone stock.
 

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Discussion Starter #12
man it's been a while - nice to see this old thread dragged up and new information added. Now my A/F Ratio gauge not only does not bounce at idle, but under load the reading looks distorted and instead of the gauge bouncing from lean to rich, it just kinda halfway lights up all the LEDs at the same time and they kinda flicker all around. I suspect it's a connection issue, but I haven't been able to hunt it down.

Anybody else have any of these issues? Thanks for the responses so far everyone.
 

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Im thinking its normal. Its only reading a volt or 2. Since its reading somewhere in between that, I figure thats why you will see more than 3 or 4 led's lit up.

Mine is barely lit at idle also. The second I step on the gas the gauge jumps to green led's.

I would only worry if your boosting and you have no green led's period.

I once had a bad ground problem on my car and only the orange led's would light up. When I fixed the ground, I started seeing the greens again.

When my car was not tuned the last 3 greens only were lit(wot). After i had a dyno tune, all the green led's were lit(wot) and maybe 1 orange led.
 
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