'99 Corolla "Waste Spark" Ignition Coils - Cyl 2, Cyl 3, Random Cyl Mis-fire Detected

Sep 30, 2017
Vancouver, BC Canada
Per the detailed title, I both have the above 3 codes being registered and, somewhat strangely to my way of thinking, I am experiencing a low rpm miss that comes-in just beyond cold start. ... Meaning, all is good until coolant temp is closer to normal operating temp. Also, this misfire appears to be throttle position dependent. I can experience same, then if I back-off the throttle a 'wee bit, it can disappear. Going deep into the throttle causes backfires. Generally the miss only occurs at low- to moderate RPM's. Higher RPM's - NP.

It clearly is not a clogged fuel filter (fuel pump inlet sock) as higher RPM's are NP.

I am 'gonna switch positions of the coils, as cyls 2 & 3 are fed by one; cyls 1 & 4 by the other. If the prb migrates that likely is an indicator of a prb coil.

Plugs are good; spark plug leads are new.

Any idea re the prb, other than a bum coil?

Is it possible that the richer mixture on startup CAN be ignited with a weak spark, but normal temp "leanish" mixtures are a prb? But why only at lower rpm's?

Thank you to anyone who could advance a thought on this.

I attach a screenprint of my older Android phone with the Torque app. The O² sensor voltage flips with, I believe, adequate frequency...


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If it's between those two only, and the same coil fires both of them, and the other cylinders are fine, it's probably the coil. Swap 'em and see what happens :)