Can bad coils cause missfire in opposite cylinders ?

[stunt2]

Got multiple missfires on drivers side head. Sometimes on all three cylinders, more often on 4-6, almos always on 6.
Brand new two electrode NGK's, brand new wires. Injectors tested good. New air filter. No vacuum leaks.
But the problem still exists.
Any suggestions ? Can bad coil packs cause missfire on opposite cylinders but fire its own plug without issue ?

 

[T4R2014]

Swap coils and see if the misfire moves. Otherwise a new coil is about $80, not terrible.

 

[phattyduck]

Any suggestions ? Can bad coil packs cause missfire on opposite cylinders but fire its own plug without issue ?

Yes. The 'far' cylinder has a wire to go through, which adds resistance/impedance. The oil basically also has a positive and negative output (two ends of the same winding internally) and depending on the issue one output can be weaker than the other.

As was already said, move the coil and see if the issue follows.

-Charlie

 

[thennen]

If you DO replace, use OEM and not aftermarket.

 

[brillo_76]

My signature has a thread on how to test the coils and wires. Even though, it is extremely rare. A coil can test good and still be bad..:-( This is why swapping locations is recommended..

 

[mtbtim]

It would be a hell of a coincidence for 2 coil packs to go bad at the same time, but it's certainly possible.

Sometimes coil packs go bad from oil intrusion into the spark plug tube from failed spark plug tube seals. When you remove the coil packs and they are drenched in oil, that could be your problem.

Here's the wiring diagram for the 5VZ-FE engine so you understand what coil pack on the passenger side corresponds to the cylinders on the driver side.

 

[stunt2]

Tried to check timing marks today. I know that crank sprocket has its mark, but by the position of the crank pulley notch can I tell that the belt is off by a tooth or even three ? Shouldn't it be at 0 when cam gears are aligned?

 

[stunt2]

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[2TH4IST]

If the crank is at 15° and the cams line up, there is a problem. The crank should be at zero and the cams lined up with their respective marks.

 

[phattyduck]

Tried to check timing marks today. I know that crank sprocket has its mark, but by the position of the crank pulley notch can I tell that the belt is off by a tooth or even three ? Shouldn't it be at 0 when cam gears are aligned?

Time to tear deeper into it. Your crank is off at least 1 tooth compared to the cams - unless the crank pully has failed (slipped at the rubber ring) or the woodruff key fell out and the crank pully is not correctly aligned. Either way, start taking off those lower parts and get it fixed.

At least none of this will cause lasting damage to the engine.

-Charlie

 

[stunt2]

Corrected the timing marks. It was one tooth off at the krank. Car runs smoother and pulls better at low rpms. Cleared the fault codes and all is good within 20 miles range from mechanic to home. Will monitor if they come back again.