'8746 Peaked o2 reading - Third Generation F-Body Message Boards

Jeff91RS · 09-01-2009, 06:18 PM

I have been struggling with tuning my 350 tbi and i have ran wires straight from the ecu to the o2 sensor and and the o2 sensor ground, I hooked the ground wire up to a header bolt. I did this because I was constantly getting a reading of between .465 volts. I have a brand new o2 sensor and it is reading at 1.065 volts on my WINALDL. What could cause this?

RBob · 09-01-2009, 09:01 PM

If the O2 is reporting correctly it may be that the engine is running rich.

As a test, disconnect the wire from the O2 sensor and ground it to the O2 ground point. This should make WinALDL read close to 0 volts.

The O2 sensor ground to the ECM is important as it is the only reference for the O2 sensor amplifier in the ECM.

RBob.

Jeff91RS · 09-02-2009, 02:42 AM

I phrased that wrong, the o2 reading pegs to over 1 volt the second the key is turned on regardless of if the engine is running or not. I ran a new o2 ground from the ecu to a driver side header bolt. The car won't idle.

I will try your test tomorrow when my class gets out.

thanks

Jeff91RS · 09-10-2009, 09:36 PM

Ok, my temporary o2 ground wire melted on a header so that problem is solved, now to get the car actually running again.