no spark on #2 and #4

[Bruce_M]

I am having spark problems with my 2000 Lexus ES300 that has 119,000 miles on it.  Cylinders #2 and #4 are not receiving any spark, which resulted in the catalytic converter for #2, #4, #6 completely burning and melting away with the melted chunks plugging up the aft-most catalytic converter.  The only codes shown are P0300 (multiple misfire), P0301 (#1 misfire), P0302 (#2 misfire), P0304 (#4 misfire).

I replaced all 3 catalytic converters, replaced all spark plug, all coils, both cam position sensors test in the middle of the allowed ohms.  Have moved swapped coils between #2 and #6, and then #4 with #6; no matter what coil/cylinder position, rpm only drops when #6 coil disconnected, and no rpm difference when #2 and/or #4 disconnected.  Definite rpm drop when #1 coil is disconnected.

Unfortunately, the catalytic converter for #2, #4, #6 glows orange after only about 60 seconds of idling.

Any ideas will be very appreciated.

Thank you.
 

[Bykfixer]

Have you had compression checked? 
 

Quite possibly the ECU has forgotten to send signals to the cylinders. ie bad ECU.   At one point Toyota had some issues with capacitors failing in them. 
 

You can try cross matching ECU's at LexusPartsNow to see what cars it was used in and perhaps snag one at a local junkyard to see if that makes a difference. 

[Bruce_M]

Thank you for your response; no, I have not checked compression as compression is unrelated to the lack of spark delivery to 2 of the 3 cylinders on one bank.

A problematic ECU is a prime candidate for the source of no spark.  I have both shop repair manuals for this vehicle and trying to trace down the wiring to find a good ohm/voltage test for the spark source for just 2 cylinders is challenging, to say the least...meaning I haven't found it yet.  I am hoping to find some type of test that will validate the actual problem before I start replacing parts just to be replacing parts.

Thank you for your response.