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Old 10-12-2013, 02:48 PM   #1
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Default Oscillating AFR in Tuner Studio

99 miata, MSM engine(ish), MS2pnp.
What could be the cause of oscillating AFR signal voltage in TS?

Specifically when I've completely rewired the AFR gauge/controller, even the D15 connector and used the ECU ground pin (pin 15) with the AFR controller.
This helped lessen the oscillation but it's still there.
The 0-5v signal at the AFR pin is solid and doesn't oscillate.

ECU ground? I've read that it ground near the brake booster but wasn't sure if that was I'm 99s as well.

I also can't seem to find a picture of all the 99s grounding points so I can check them.
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Old 10-12-2013, 08:13 PM   #2
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How many points does it oscillate and where?

What sensor do you have and how old is it? Location in exhaust?
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Old 10-12-2013, 09:22 PM   #3
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The amount changed after I rewired the AFR controller and grounded the ecu the same ground as the conroller and chassis/ground strap to the bracket on the head (near the oil dip stick)

It happens when the car isn't running(as shown in the pictures) and extremely when the car is running

Also when I mean it oscillates in TS I mean only in TS, my gauge doesn't oscillate at all.



I have prosport evo gauges for afr and boost, I've had them fir a little to a year.
the o2 sensor is new the controller is new. Location is stock rear o2 bung on the MSM downpipe (about a foot away from the turbo)
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Oscillating AFR in Tuner Studio-before_zpsedb08c56.png   Oscillating AFR in Tuner Studio-after_zps848915d4.png  
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