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1carnut · 03-11-2012, 07:43 PM

I think I am making progress. Here is what I've done so far and results.
1. Replaced Grommet for PCV. Did not seem to make much of a difference. Also replaced straight through PCV (looked like original). Still no appreciable change.
2. Cleaned IACV valve. This seems to have improved things (idle not as wild) but they are still not fixed.
3. Unplugged O2 sensor. This cures the stumble at light throttle since it doesn't go into lean burn. Found what I believe to the correct replacement (24300) on oxygensensor.net for $189 so I ordered that.
4. Tested a few lines for vacuum leaks but did not find any.
So now I have some more consistent symptoms but I'm still not exactly sure of the cause. I haven't tried the EGR system as of yet. Now when I drive the car and take it out of gear to coast after being warmed up, the idle slowly fluctuates between about 800 - 1500 rpm if I am above 50 mph. As the car slows the idle fluctuates between about 800-1100 or so. Once I stop the idle will stabilize after about 5-10 seconds and sits right about 1000 rpms. I thought this was a bit high but did not want to adjust it with the O2 unplugged. I'm hoping that the new O2 takes care of the lean burn stumble.

03-11-2012, 07:43 PM	#15 (permalink)
1carnut EcoModding Lurker Join Date: Jan 2012 Location: Lebanon, OH Posts: 76 Sparky - '07 Toyota Prius Base Voltage_kwh - '18 Chevy Volt LT 90 day: 151.04 mpg (US) Voltage_gas - '18 Chevy Volt LT 90 day: 43.38 mpg (US) Thanks: 19 Thanked 13 Times in 11 Posts	I think I am making progress. Here is what I've done so far and results. 1. Replaced Grommet for PCV. Did not seem to make much of a difference. Also replaced straight through PCV (looked like original). Still no appreciable change. 2. Cleaned IACV valve. This seems to have improved things (idle not as wild) but they are still not fixed. 3. Unplugged O2 sensor. This cures the stumble at light throttle since it doesn't go into lean burn. Found what I believe to the correct replacement (24300) on oxygensensor.net for $189 so I ordered that. 4. Tested a few lines for vacuum leaks but did not find any. So now I have some more consistent symptoms but I'm still not exactly sure of the cause. I haven't tried the EGR system as of yet. Now when I drive the car and take it out of gear to coast after being warmed up, the idle slowly fluctuates between about 800 - 1500 rpm if I am above 50 mph. As the car slows the idle fluctuates between about 800-1100 or so. Once I stop the idle will stabilize after about 5-10 seconds and sits right about 1000 rpms. I thought this was a bit high but did not want to adjust it with the O2 unplugged. I'm hoping that the new O2 takes care of the lean burn stumble.