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Discussion Starter #1
I have an Autometer sportcomp wideband - PN 3378, running Microsquirt on a 91 LX. I can get the wideband calibrated right on, sitting in the driveway. When I go out for a drive to do some tuning, the wideband calibration goes off. Sometimes as much as 2-3 full points. The Autometer wideband seems to stay dead on, giving accurate information and the Microsquirt/TS seems to go out of calibration. I try to use Autotune but it pulls all the fuel out to 16+ AFR (wideband gauge reading) and the car starts to sputter while Tunerstudio says its holding at 12.0. Its pulling fuel, going against the AFR table values. I have to pull over, and add fuel back to those cells. Then when I get back home in the drive way they went back to matching. I can drive and tune the car going by the Autometer gauge, cell by cell with good results.

I had the wideband originally grounded to the firewall and have since moved it to the battery. I have also calibrated the range in the Autometer gauge to match the outputs of the parameters in Tunerstudio: 0-4v = 10-16AFR. It still seems to go out of range.

I'm new to tuning, so it could be something I've overlooked. Really hoping that I can get this autotune up and running. Tuning cell by cell isn't fun.

Thanks!
 

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So there should be 4 wires on this wideband that need attention. I use the pro-comp widebands on my megasquirt cars but they're similar.

Wideband RED - switched 12v from anywhere possible

Wideband Black - Ground from anywhere (chassis is fine here)

Wideband Blue - To Megasquirt "O2 In"

Wideband Blue/Black - To Megasquirt "Sensor ground" (on ECU board, not battery)

What ECU do you have? Without that information, I can't tell you exactly which pins to use.

I know you said you calibrated the Tunerstudio AFR limits, but make sure the wideband limits match (Min=10 and Max=16 like you said above)

Make sure any narrowband (stock) o2 sensors are disconnected for good measure.

If you'd like, I can look over your tune file to see if there are any glaring issues with settings that may affect AFR calculations or fuel settings.
 

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Discussion Starter #3
I have the Microsquirt package with the harness adapter to fit my foxbody.

I think my problem is the blue/black ground off of the gauge. I don't remember seeing a wire on that plug and play harness to connect the negative to, only the positive, and a fan wire...

I am away from my computer right now but I will get back to you in a few hours.

Thanks!
 

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Discussion Starter #5
Yes, that's the kit.
 

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Couldn't find any documentation for their particular harness but you need to basically figure out which wire on their harness goes to Pin 20 and connect the blue/black to that. should be good after that.

I emailed them for you to see if they had a manual.
 
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