P0301 Cylinder 1 Misfire

I have a P0301 that will not disappear on a 96 Tacoma 5VZFE,3.4.
After a month of replacing everything on the outside of the engine that could possibly be related (Plugs, wires, alternator, air intake tube, everything except the coil pack, but switched it to another cylinder, P0301 was still there).
At that point I replaced the head on the right side of the engine with a remanufactured head, still no luck.

Any other thoughts?

 

Have you replaced ignition coils? That might be it if you haven’t....

My mistake I see what you typed.. but you should replace the ignition coils but I know they’re a lot of money

 

I would start with new plugs first.

 

A few weeks ago I was having problems with one of my cylinders my truck was vibrating a lot. So I went to autozone and they told me I had to replace the spark plugs so I did. But it kept vibrating so I just change the spark plug wire and it stopped and now it runs way better

 

is there a sealing/compression problem in #1. I would preform leak down test to see if there is. If this test shows good sealing I would examine the camshafts really well. Did the new head come with its own camshafts or did you transfer yours to the new head?

 

Alot of times this is related to the incorrect spark plugs. You need the double prong plugs as depicted in the little picture on the engine. Owners manual gives the correct Denso PN, or you can get the plugs from the dealership.

 

I have replaced the Bosch plugs with NGK plugs, the plug wires are new.
Did a compression test before replacing the head. all was fine. Swapped the coil packs on cyl. 1 and 3 to verify coil was good.
Misfire still on cyl 1.

 

Camshafts were moved to the new head.

 

Which NGK plugs? There are specific plugs that the 3.4L needs to operate correctly.

 

NGK 5464 plugs.

 

You got the wrong plugs then.

https://shop.advanceautoparts.com/p/ngk-iridium-ix-spark-plug-bkr5eix-11-5464/15650078-P

You need the double prong plugs as depicted on your motor.

 

You need similar to these, either Denso or NGK

https://shop.advanceautoparts.com/p/ngk-standard-spark-plug-bkr5ekb-11-3967/19650155-P

 

That is what I put in the truck.

 

Spark plugs are pretty dumb. They fire, life goes on, mostly. I've use single electrode, double, triple, and quad ground strap. They work fine. This will not be your problem.
Coils almost never go bad. Again, they are so simple and dumb.
You didn't mention anything about injectors. I'm betting you have 200-250k miles. 1 or 2 injectors go bad at this age. This is what I'd be betting on. Might test wire continuity too, to make sure you don't have a broken wire going to that injector.

 

Injectors!

 

Cylinder 1 injector is new.
One of the first thing I did.

 

150,000 miles

 

well I could have saved myself a bunch of typing if you had mentioned that LOL

Check out your wiring continuity from the ECU plug to the injector?

 

Right, 3967 is the correct ones. 5464 are incorrect.