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Canadafix, Canadian Class A
Category: Chevy
Satisfied Customers: 1632
Experience:  Have owned/operated an automotive repair shop for the last 19 years working on all makes and models of vehicles
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code read po305 misfire cylinder 5

Resolved Question:

code read po305 misfire cylinder 5
Submitted: 5 years ago.
Category: Chevy
Expert:  Canadafix replied 5 years ago.
Welcome to Just Answer.

You did not mention what has been looked into yet, so I will begin with some basics.
First of all the spark plug. If it has been a while since the plugs were changed, it may be a good time to do so.
Same with ignition wires, distributor cap and rotor.
It will not be a coil issue as it is isolated to one cylinder.

Next would be a possible fuel injector issue. These models had some issues with sticking injectors.
Get some good fuel injector cleaner and try it.
If it does not free up, you may need to get them hooked up to a pro machine.

If the fuel injector is OK and the spark is good, the next step is to check the compression to verify the valves and piston rings are OK

Your questions/comments are welcome to me in a reply.
Thank you,
Customer: replied 5 years ago.
car has 147000 miles: plugs have about 35000 miles I asume they are fine wires look good but I'll check , after using fuel injector cleaner is there away to check the injector
Expert:  Canadafix replied 5 years ago.

Not easy to check. These injectors are unconventional from usual injectors.
You will know if the cleaner begins to work if the misfire goes away.

Don't be too sure about the spark plug.
Swap it with another cylinder (if you want to keep using them) and see if the misfire moves to the cylinder you put it into.

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