Random misfire/ cold start rough idle codes

[Jesse Wisniewski]

Hello, I’m new here but have been having trouble with my truck. A month ago I started getting a bank 1 o2 sensor imbalance code coming up and now along with that code I’m getting cold start rough idle, random misfire as well. I replaced plugs, wires and Seafoamed it. It went away for about two days and now is back. Thanks for any help in advance 

[Jsdirt]

More than likely it's a bad AFR or o2 sensor, whichever they're using on those. Use a scan tool and watch the data on that particular sensor. Also check the voltage engine off, key on ... then unplug it and see what the voltage does. That'll confirm wiring and connector integrity. With an o2, you should see 450mV bias voltage key off. Unplugged voltage should go high (up to 5v).

 

You can also introduce rich and lean conditions and watch for changes on the scan tool. Vacuum leak by pulling a hose to test lean condition, and spraying brake cleaner into a vacuum line to create a rich condition. Compare to the other good bank to see if the sensor is lazy, or fixed rich or lean.

Edited February 4, 2022 by Jsdirt