This seems to be a somewhat problematic problem that has been solved in other threads and whatnot, but this one is pretty odd because of the gauge I'm using.

I'm using the Innovate Motorsports PSB-1:Powersafe Boost & Air/Fuel Ration Gauge Kit + Megasquirt 2 NA Miata
Accordingto the manual, the default analog output configuration is 0V = 7.35 AFR and 5V = 22.39 AFR, which is what I set it to in Tuner Studio.

PROBLEM. ECU AFR always shows 1-2 whole units above what the gauge reads. Currently its reading roughly 12 with ignition on but car off (This is another issue that I hope will be solved by first cleaning, and maybe replacing if that doesn't work, of the AFR sensor itself but I haven't done that yet) (Maybe this has something to do with it and wiring is wrong?) - 12v power from cruise control, ground works the same from main ECU ground + megasquirt top connector chassis ground (pin 5) - I haven't exactly tested this but I will double check tomorrow but I think the chassis ground from the top of the ecu works better than the bottom connection (as in its 1-2 off vs 3-4)

I hope that made sense. I just got the car for a pretty solid price from a great gentleman. It's certainly a fun project, and any help is appreciated! Also, if you know a good tuner who can do something online, I would love to get in contact, as that's the next step.

Thinking out loud: Kind of a weird issue. I was doing some alligator clip testing, but I didn't have a wire long enough to double-check it at various ground connections in the engine bay; that's the next step but for some sneaking suspicion, I have a feeling I should double-check all the wire connections with a voltmeter coming off the innovate psb-1.

 

When the gauge is reading 12 with ign on but engine off, has the car been running recently? The air inside the exhaust is stagnant once not running.

Just to double check, you're clicking write to controller, when setting your voltage scale in the afr calibration?

Also is the correct output wire hooked up from the gauge. I recently swapped from innovate to aem, and I had some bad readings in TS from using the wrong output wire. I had assumed the output + was needed, when actually the output - was the correct wire for my setup.

 

Take it out of the exhaust, turn it on, and verify the output wire reads 5v or close to it. You can get the serial cable from innovate if the PO didn’t give it to you, and use their software to verify or resend the default config. Last I checked with an LC-1, it was changeable.

 

What curly said. Check the voltage output with the sensor out of the exhaust pipe.

FWIW - I had an LC-1 years ago and I could never get it to remain stable. I have no experience with their PSB-1.

 

So I did some rewiring. The PSB-1 signal wire hooked up to the miata OEM wiring harness o2 and I thought there could be some interference, so I made a new line and hooked it directly to the megasquirt 2. Also, the ground wire was kinda funky was I was resistance multimeter checking (using a ground on the ecu to car battery negative, and nothing showed up) so I moved it to another ground that did work when I resistance checked it to the car negative terminal, however the resistance said that it was 120 give or take which might be concerning. However, now on the tuning software, it is about 1 AFR above what the PSB-1. (After all this, I was looking at it, and the negative terminal has 2 butt connectors on it, and the signal has one, but they seem solid, but I wanted to mention that in case I should remove and direct solder.) After I did all that work and buttoned it up I decided its time to move to the o2 but that will be for another day, will also check the boxs the PO gave me to find the service computer connection wire for the PSB-1 (or make my own). There's also this thing with these innovates where they have to be calibrated outside the exhaust, then put inside the exhaust, and I'm not sure if that's done. Will look into it tomorrow.

Currently, the ECU is reading a higher voltage than the PSB-1. Would this not indicate a grounding issue, primarily a software / ECU issue?

Thank you (and everyone who's responded) for the help!

 

Hey!
Firstly, yes, it was running correctly before, and it would do this. Slowly, it rises to around 22 after a few hours. And yes, I am clicking 'Write to Controller' when I change the voltage scale in the far calibration. I've done some messing around with those voltages and other presets.
Yes, the wires are correctly connected. According to the manual, the yellow wire goes to the ECU, and the black wire is ground. Then, it's a 12V power, and another wire that goes to the headlight dimmer feature. I posted a reply below about some things I discovered that lead to an improvement but its still 1 AFR off, I assume it should be pretty close like +/- .2

 

I've got a PSB-1 too that does the same thing (not a whole AFR point, more like .6 leaner on the ECU than the gauge) and I grounded it to the throttle body ground and it didn't really fix it. It's just close enough that I haven't messed with it. The only thing I can think to do is add that .5-.6 AFR to the AFR target table and retune so that I actually hit my real targets and not like 11.2-11.3 that my car likes to do in boost based on my 11.8 target in tuner studio.

 

I'm not the OP, but I have exactly the same situation and I did change my PSB-1 ground to run to the grounds on the throttle body which as far as I understand is where the ECU grounds on my '99. The problem persists, infact it really didn't make any difference which is weird considering it used to be grounded to the underside of my dash.