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View Full Version : Wideband wiring question for Megasquirt



BlitzWing
04-11-2015, 09:13 AM
Simple question really, I've wired my wideband into the Black and blue wire from my stereo as that's an ignition only power source and earthed it to the same point at the stereo. In regards to the white aux wire I've plugged it to the yellow wire on the DB-37 connector on my MS2 (it does not have a pink wire and the builder confirmed its this wire on the 94pnp MS2)

this sound right to you guys? seems like this is the go-to set up for the AEM Uego. I've not got a battery in the car so I cant just turn it over to see what happens also I dont want to risk shorting something.

Satisaii
04-11-2015, 10:05 AM
That looks ok. You might have some issues with noise. I have installed too many O2 sensors to remember specific instructions for AEM, so the following may not apply. I ground the unit to the same point on the head as the ECU and use a cleaner power supply than the radio. Some instructions specify to not use the radio power. The reason I do this is that the MS gauge can read differently than the gauge that comes with the sensor. Wiring it this way can reduce that difference. You will also need to set it up in the MS.

The short answer is that you are not going to short anything.

BlitzWing
04-11-2015, 10:44 AM
cool thanks. I've been sent a tune by the guy who built the MS2 for me to match my set up with a common base tune. If the MS2 does give me problems I can always move it and splice it into the ECU harness. Thanks again for the advice.

joe morreale
06-05-2016, 11:04 AM
A question along the same lines. (don't mean to hijack) Can the power line from the cigarette lighter be used to power the wideband? A hard ground into metal going to work?

kung fu jesus
06-05-2016, 04:25 PM
Power is OK, but I would use the same ground point as the ECU, even if that means running another wire through the firewall.

forrest95m
05-02-2017, 07:12 AM
I wired my power from the blue wire under the dash, then ran a ground from the gauge in the interior, through the firewall, and put a ring terminal so I can ground it on the engine block. Also, from what I've heard a bad ground (something you might encounter using the stereo ground) will throw off your wideband reading in megasquirt
*Didn't realize I just bumped a year old thread, sorry

freedomgli
05-02-2017, 01:33 PM
Each Megasquirt install and each wideband oxygen sensor controller install is a little bit different in how power, ground and signal are handled. Always follow your ECU and WBO2 manufacturer instructions. Even when you follow the instructions to the letter you may still have some inaccurate readings. The analog output of most WBO2 controllers is 0V-5V. Power and ground becomes absolutely critical because very small differences in reference voltage or being on different ground planes can result in voltage offsets that affect your AFR reading. Remember, garbage in, garbage out. Assuming your install is done correctly, you can often compensate for minor voltage offsets by tweaking the settings in Tuner Studio under Tools> Calibrate AFR Table> Custom Linear WB. This process is a bit trial and error and is done mostly so that your physical AFR gauge matches what your ECU is seeing. This also assumes that the AFR gauge is reading correct.

The best solution I've seen is to take the digital output from your WBO2 controller and send it to the ECU over CANbus. Provided everything is wired and configured correctly, this digital signal gives you the most accurate AFR reading.

kung fu jesus
05-02-2017, 04:53 PM
Common ground points are critical.

Agent☣Orange
05-02-2017, 10:42 PM
The best solution I've seen is to take the digital output from your WBO2 controller and send it to the ECU over CANbus. Provided everything is wired and configured correctly, this digital signal gives you the most accurate AFR reading.

More details on this please.

freedomgli
05-03-2017, 10:27 AM
More details on this please.

http://www.trackspeedengineering.com/Engine-Management/mslabs-can-wideband-module.html
http://mazdaroadster.net/showthread.php?11075-For-more-speed-add-lightness&p=207571&viewfull=1#post207571
http://mazdaroadster.net/showthread.php?11075-For-more-speed-add-lightness&p=207646&viewfull=1#post207646
Megasquirt 11bit CAN broadcasting protocol, including dash broadcasting PDF (http://www.msextra.com/doc/pdf/Megasquirt_CAN_Broadcast.pdf).
https://www.diyautotune.com/product/can-egt-8-channel-thermocouple-interface/
https://www.diyautotune.com/wp-content/uploads/can-egt.pdf
https://www.14point7.com/products/megaspartan
https://cdn.shopify.com/s/files/1/0189/1312/files/MegaSpartan_User_Manual.pdf