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Nikzilla · 02-11-2014, 04:10 PM

Ok, I have DataScan running, and here is a brief explanation of what happens.

Conditions:

Very light throttle acceleration, or constant speed cruising.
TP Voltage between 1 and 1.5V.
No boost.
RPM is at least 2500.

Issue:

Narrowband spikes to the rich end (showing 100-120) and stays maxed out.
Wideband spikes to the lean end (20+) and stays maxed out.
Car stumbles.
MAF voltage and Duty Cycle stay consistent when this happens, and the fuel trim doesn't budge at all (stays at 100 during the whole process).
Quickly increasing throttle resolves issue for a second (fuel enrichment during fast TP acceleration).

Here is a screenshot of the data log with explanations on the graph.

Can anyone help me figure out what's causing this?

Also, I did replace the O2 sensor. I thought it would fix the issue, but it didn't.

If I unplug the O2 sensor, I don't get a lean spike on my wideband. However, it still runs too lean before boost (like at 16-17), but runs fine under WOT with boost (11.0 AFR). The difference is, it doesn't lean out continuously until it maxes out the gauge, like it does if the sensor is plugged in.

02-11-2014, 04:10 PM	#1
Nikzilla Zilvia Member Join Date: Jun 2013 Location: Los Angeles Age: 26 Posts: 291 Trader Rating: (0)	[SR20DET] What is my O2 sensor doing? Ok, I have DataScan running, and here is a brief explanation of what happens. Conditions: Very light throttle acceleration, or constant speed cruising. TP Voltage between 1 and 1.5V. No boost. RPM is at least 2500. Issue: Narrowband spikes to the rich end (showing 100-120) and stays maxed out. Wideband spikes to the lean end (20+) and stays maxed out. Car stumbles. MAF voltage and Duty Cycle stay consistent when this happens, and the fuel trim doesn't budge at all (stays at 100 during the whole process). Quickly increasing throttle resolves issue for a second (fuel enrichment during fast TP acceleration). Here is a screenshot of the data log with explanations on the graph. Can anyone help me figure out what's causing this? Also, I did replace the O2 sensor. I thought it would fix the issue, but it didn't. If I unplug the O2 sensor, I don't get a lean spike on my wideband. However, it still runs too lean before boost (like at 16-17), but runs fine under WOT with boost (11.0 AFR). The difference is, it doesn't lean out continuously until it maxes out the gauge, like it does if the sensor is plugged in. Last edited by Nikzilla; 02-11-2014 at 05:58 PM..