Quote:
Originally Posted by Nikzilla
It only does that under certain conditions described in the original post. Most of the time it oscillates like a happy sensor.
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So you are saying the O2 sensor works fine. but sometimes, while cruising, it stops working, and goes full "rich" while the wideband shows a lean condition? And the engine struggles? Does the car decelerate? Does the throttle position increase to keep the rpm constant?
It sounds like the engine flips into open loop during your "condition", which would explain the sudden locking out of the fuel trim.
That could be the maf hot wire (clean it, what does the maf voltage do compared to the rest of the time? ) or an air leak between the maf and turbo (you are not getting enough air to pass the maf hotwire). It could also be a wiring issue (a sudden intermitten ground causing a sensor to fail for an instant) , a faulty tps (you would see the tps signal fluctuate, or spike).
But none of those things forces open loop, unless you meet the condition for open loop, or the O2 sensor fails, I am not sure why it would go there. If the maf voltage suddenly spikes up, or the TPS suddenly spikes up, yeah that would force open loop, your O2 would peg rich (narrowband)- but you would
probably see the voltage spike on the data tool.
I still say, check for air leaks, clean the maf, change the maf hotwire (SOHC KA maf hotwire for redtop #62 ECU easy to find) first.