I wento go to lunch today from work and the truck is running horribly! It is a definite dead on miss. I go to the shop and it is reading cyl#6 misfire. I check wires connections etc. I pull the boot and check for spark. Cyl 6 has no spark and cyl 5 has a very small spark. Is it possible for both coils to go at the same time?

 

where are all the tech guys?

 

1(coil)-4(wire) are on the same coil, 3(coil)-6(wire) same coil.5(coil)-2(wire) same coil.

So for a cylinder#6 misfire,code P0306..the wire that's stamped 3 on wire insulation(driver's side rear) has no spark?

Also cylinder #5,code P0305,coil (rear passenger side) has weak spark below the coil pack?


Sounds like you are confused..That's ok,its kinda confusing the way Toyota numbered its wires to reflect the coil locations,not the plug wire locations...

For a #6 cylinder flat out miss..most likely its the wire..usually when the coil goes you will have both cylinders that share that same coil start dropping as well..because if it was a coil you might get a p0303 code,cylinder #3 as well.and with 2 dropped cylinders the truck would barely run...

So looks like its time for a wire set(#6 miss(wire),but#3(coil) is ok)...

If you still suspect a coil is going bad..switch it with another one..say #1(passenger's side front coil)..All 3 coils will interchange...If your miss goes to #1(p0301) or the shared wire for that coil(p0304),cylinder #4...you are right about your coil being bad........

 

actually its cylinder 6 that was mis-firing. after playing with coils and swapping them back and forth the miss then went to 4 and 6

 

If you are getting even# codes/misses..keep thinking wire set..

 

Seems like it was one coil that failed and a second one that was throwing just a weak spark.

 

So I replaced the coils on cylinders 1 and 3. Running great. I think I may go ahead and get a new coil for that last one since it was the same brand as the other two that failed. I had an issue previously with the truck running bad. I was the one with the huge thread that turned out to be a loose crank bolt and worn crank gear. At the time before it was diagnosed I replaced the OEM coils with these no name ones that failed. So i would not be suprised if this third one goes soon too.

Also, I have seen many Toyotas (ES300, Sienna, Avalon) that use the 3 coils for 6 cylinders. Many times a coil has been going bad and the cylinder the coil sits on fires fine whereas the one that is connected by the wire from the same coil misfires.