Coil-on-plug Failure?

[mean dad]

2010 Toyota Matrix

Vehicle started running rough and would barely hold an idle. Sprayed starting fluid around the intake components with no joy.
Poked and prodded a bit, and noticed that one of the coils would emit a slight buzzing sound when the car was turned off (almost like it's releasing pressure, but electrical). Re-started the car and turned it off again several times with the same result. Just a short little bzzt sound.
Swapped in a new coil pack but the sound persisted. Traded the new coil for the one next to it in case my echo location skills were rusty, with no change. The #1 coil buzzes for a second when the car is turned off.

I'm about to replace all 4 coils to be sure but I hate wasting time and money.

Any guesses?

 

[KrustyKruser]

Any change in idle or running when just disconnecting the connector from suspect or other coil packs? Maybe buildup around the butterfly in throttle body? Is it just a running issue at idle or rough across rev range?

 

[mean dad]

The pretty thing had to turn around and come back home on Friday when it started acting up. It was barely holding an idle and she said it felt like it wanted to die, but once it got going it (seemed) to run fine. We had just swapped in a new battery so I thought maybe it had no charge and wasn't up to snuff yet, so I had her come home and take my truck and I threw a battery charger on.

Started it up the next morning and it idles much lower than it should and slightly rough, but it doesn't seem as bad. It again seems to drive fine once you're going over ten or fifteen mph.

Haven't pulled power to any of the coil packs. Almost did but by that point it was over 100 degrees outside and I had tasks in the house that were calling me.

 

[KrustyKruser]

I would start with checking the throttle body. Maybe buildup from the crankcase then not letting enough air through at idle. Probably buid up of oil from crankcase ventilation.

 

[295566]

Since you swapped coil packs with a new one, and with an adjacent unit, seems pretty clear the coil isn't your problem. I'd pull the #1 plug just to ensure there's no problem there, just as a starting point.

 

[mean dad]

#1 plug is a beautiful tannish color.

 

[Rob750]

Misfire from coil/ignition likey will cause check enge light to flash or stay on steady. Loss of adaptive values from battery disconnection can cause low idle, especially if throttle dirty.

 

[Busy Little Shop]

2 items to try...

To locate spark leaks pop the hood under the cover of darkness...
first spray the engine with water then start... watch for the blue
arch of a miss fire... possible culprits are 1)bad wire 2) broken
spark plug insulator 3) corrosion in the spark plug cap...

To disassemble the spark cap use a screw driver and note any corrosion
at the resistor and spring...

 

[jafo]

quick google from carspecmn.com

When the starting battery is disconnected on late model Toyota and Lexus vehicles the engine control module loses the learned position of the idle air control valve or throttle actuator motor (throttle-by-cable or throttle-by-wire, respectively). Any buildup on the throttle bore or butterfly valve will reduce airflow through the throttle (now sitting at it’s default position), causing the roughness or hard start. The higher the mileage the more severe the condition. The repair? Clean the throttle of junk buildup and it’ll run significantly smoother. Post cleanup it’ll idle higher than normal for a bit, settling back down once it learns the idle position again. CARspec recommends using traditional carb cleaner to clear the buildup – we use a modified hummingbird feeder cleaner to reach all parts of the bore

 

[mean dad]

<3

Thanks fellas.

 

[RVFRick]

quick google from carspecmn.com

When the starting battery is disconnected on late model Toyota and Lexus vehicles the engine control module loses the learned position of the idle air control valve or throttle actuator motor (throttle-by-cable or throttle-by-wire, respectively). Any buildup on the throttle bore or butterfly valve will reduce airflow through the throttle (now sitting at it’s default position), causing the roughness or hard start. The higher the mileage the more severe the condition. The repair? Clean the throttle of junk buildup and it’ll run significantly smoother. Post cleanup it’ll idle higher than normal for a bit, settling back down once it learns the idle position again. CARspec recommends using traditional carb cleaner to clear the buildup – we use a modified hummingbird feeder cleaner to reach all parts of the bore

My 2001 Lexus RX300 had similar symptoms. I cleaned the idle control valve sensor with some CRF airflow sensor cleaner spray and all was good.

 

[anytwowilldo]

quick google from carspecmn.com

When the starting battery is disconnected on late model Toyota and Lexus vehicles the engine control module loses the learned position of the idle air control valve or throttle actuator motor (throttle-by-cable or throttle-by-wire, respectively). Any buildup on the throttle bore or butterfly valve will reduce airflow through the throttle (now sitting at it’s default position), causing the roughness or hard start. The higher the mileage the more severe the condition. The repair? Clean the throttle of junk buildup and it’ll run significantly smoother. Post cleanup it’ll idle higher than normal for a bit, settling back down once it learns the idle position again. CARspec recommends using traditional carb cleaner to clear the buildup – we use a modified hummingbird feeder cleaner to reach all parts of the bore

+1, It has probably relearned its idle by now.