Hi all,
I have an '06 yrs ncp91r yaris and for approx. 6 months now its been having an issue with holding rpm at idle. I'll explain as best I can.
While the engine is cold or still warming up, no issue. If the car keeps moving, no issue. After a bit of a drive for at least 20km the car starts having real issues with either idling at a set of lights or being stuck in very slow traffic.
First of all, the rpm at idle will fluctuate between 750 and 500 rpm. Once it gets sick of this game, which is very quick it tries to stall, which coincides with the thermo fan kicking in. Giving the accelerator pedal a nudge to bring the rpm back up again and holding it there will stop it from stalling, but will be real sluggish when I take off again. If it does stall, then the engine kicks over again with no issue for half a minute, then the problem starts again unless I'm in motion. In the six months that it's been having the issue it has only thrown the one code which was P0172 "mixture too rich".
The mass airflow sensor is clean, throttle body has been cleaned also, new spark plugs, oil and filters. As far as I can tell I'm looking at the idle air control, coolant temperature sensor and o2 sensors.
I have bought myself an ancel scan tool, which is really cool, and it shows no codes, but did show a fault with o2 sensor 2. Doing the test it shows 7 or 8 values that it tests. Although I have absolutely no idea what they mean, the values $86 and $87 are a fail while everything else is a pass. I'll post pics of the fails.
I did the scan tests on absolutely everything when the engine was cold but the power on, then again while the engine was running but warming up, then again when the engine had been for a drive for approx. 20 minutes.
Without codes being thrown, does this show definitely that bank 1 sensor 2 is up the crapper?
