NAmonty

Hello All,

I have a 1990 NA Miata and am running a Speeduino pnp setup with an AEM wideband gauge and sensor. I am getting ready for a turbo but want to get the electronics working before doing the rest of the install.

I have been having issues with my AFR reading in tuner studio since I hooked up the AEM wideband... The gauge looks like it is reading correctly but tuner studio erratically jumps between lean and rich. Even as it jumps around I don't get a similar reading. I will post a video as soon as I can.

I have the Gauge power and sensor ground wired to the ECU ground on the back left of the engine. This is how it says to wire it. But, I thought it might be getting interference so I have moved the sensor ground around and haven't seen any change.

I did find I had a vacuum leak at the throttle body, but I have gotten a new gasket and eliminated that as an issue.

Could I have either a bad gauge or a bad o2 sensor? Or is there some setting in tuner studio or on the gauge that I could change to see if the ecu reads it differently?

Any help is appreciated. I am stuck and have asked all the tuners I know.

Thank you!

der_vierte

My bad o2 sensor acted like this exactly. You can burn them - if you are unlucky - in 2 min after heating it up and not starting the car.
Now I have a physical switch in the cabin and ALWAYS start up the car, let it run 30sec and THEN flip the switch and turn the WB on.
Not a single problem now and I've burnt two of them in half a year prior to that. Both were genuine Bosch units.

I have an MTX-L . They are known to kill your sensors

NAmonty

Thank you for the reply!

I can grab another sensor and test it. But, my gauge seems to be reading right, I think... Was your gauge showing a typical number and tuner studio flickering like in the video? The video does show the gauge flickering around a little but nowhere near as much as tuner studio shows...

Also, thanks for the tip on the switch, I will grab one and wire it in just to be on the safe side!

yyuu

I'm sorry I can't help you, but thank you for sharing

NAmonty

Success! It was just the o2 sensor.

Thank you der_vierte!

I have been procrastinating fixing this issue for months and in less than 8 hours you solved the issue.

der_vierte

Happy to help