Wiring Wideband Into PNP

theconductor

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I'm getting ready to wire in my plx wideband to the pnp. I believe @a91what told me to use pin21. Do I splice the wire to the wideband into that wire then disconnect my O2 sensors?

When that is done, what will I need to do to the software if anything? How will affect my current tune?



Another thing I've been wondering is how to set the base idle with Megasquirt, i.e. proper position of the throttle stop and blade. Or is it all completely controlled with the IAC?

Thanks,

Kyle
 
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awing

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Yes, on the MS PNP options port 21 is the Oxygen Sensor input, and just as important is pin 22 the signal ground. I had a hard time finding the documentation for your wideband, but you want to use the 0-5V analog ouput and the analog ground and connect those to 21 and 22.

The jumper you're talking about is specific to your wideband and the manual says to just leave it in place if you're only running one plx wideband.

After you have the 0-5V hooked up you'll have to calibrate the values in TunerStudio to match the plx.
 
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a91what

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The above is correct, you could also tie it into the passenger side O2 from the main harness if you needed too... but i really suggest pin 21 on the options port.
 
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theconductor

5 Year Member
Aug 9, 2007
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Roseville, CA
www.finalgravitybeer.com
Yes, on the MS PNP options port 21 is the Oxygen Sensor input, and just as important is pin 22 the signal ground. I had a hard time finding the documentation for your wideband, but you want to use the 0-5V analog ouput and the analog ground and connect those to 21 and 22.

The jumper you're talking about is specific to your wideband and the manual says to just leave it in place if you're only running one plx wideband.

After you have the 0-5V hooked up you'll have to calibrate the values in TunerStudio to match the plx.

First off, thank you. You're saying that I should run the ground for the plx device to pin 22 instead of a chassis ground?
 

a91what

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First off, thank you. You're saying that I should run the ground for the plx device to pin 22 instead of a chassis ground?
two different grounds, you have the heater ground and the sensor ground. the heater ground need to go too chassis, the sensor ground needs to be tied into the sig rtn or sensor ground at the ecu.
 
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awing

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I have no clue what the heater ground is. Currently the wideband is ground to the chassis and working fine and the PNP I assume is ground via the harness.
The main power going into your wideband is running the heater too. Chassis ground is fine for all loads like this. Signal ground is reserved for important sensors like wideband, IAT and CLT. It's important to keep them separate or large loads like cooling fans, fuel pumps, etc will throw off your sensor readings because of ground offsets.

Your wideband has two grounds, one you've grounded to the chassis to power it which is fine. The second signal or analog ground probably isn't connected anywhere, that's the one you want to wire directly to your MS signal ground.
 

theconductor

5 Year Member
Aug 9, 2007
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Roseville, CA
www.finalgravitybeer.com
The main power going into your wideband is running the heater too. Chassis ground is fine for all loads like this. Signal ground is reserved for important sensors like wideband, IAT and CLT. It's important to keep them separate or large loads like cooling fans, fuel pumps, etc will throw off your sensor readings because of ground offsets.

Your wideband has two grounds, one you've grounded to the chassis to power it which is fine. The second signal or analog ground probably isn't connected anywhere, that's the one you want to wire directly to your MS signal ground.

Now I'm even more confused. I didn't wire the wideband to the power running the heater, it is not connected via the cars wiring harness. The PLX oxygen sensor connects directly to the PLX sensor module. The wideband only has one ground. There is a 0.5v output to connect to an aftermarket ecu.

View: https://drive.google.com/file/d/1S79VSwt4LsVELBgBW-aCW3dJ9PFssLkT/view
 

awing

Member
Jul 29, 2019
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Westport, MA
Now I'm even more confused. I didn't wire the wideband to the power running the heater, it is not connected via the cars wiring harness. The PLX oxygen sensor connects directly to the PLX sensor module. The wideband only has one ground. There is a 0.5v output to connect to an aftermarket ecu.
No, I apologize for throwing generic advice out there. It looks like you don't have an analog/signal ground on your wideband, I had assumed that unit would have it. Use the 0-5V output to MegaSquirt. If what tunerstudio and your gauge shows disagree you can tweak the calibration to get them to line up better.
 
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