Im getting a P0301...


Ive replaced and double checked all 4 ignition coils, all 4 spark plugs, fuel injector, PCV hose, Canister Purge Valve... still throwing code so still cant pass emissions.


Ideas? Thoughts? Suggestions?

 

A code P0301 may mean that one or more of the following has happened:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression

So you checked some of these, but did you move the spark plug from #1 to say #3 ?
Same with the coil, do this one at a time to avoid confusion as to was it the plug or the coil?

You don’t mention investing the o2 sensor or the catalytic converter or a compression test
You could also preform a fuel pressure test, a test kit is available at most parts palaces near you.
Sometimes the fuel rail can clog up near #1 injector causing low fuel pressure to it causing a misfire.
Remove the fuel rail and clean it out

 

Year, model and engine size please.

While you were busy throwing parts at it, did you do a compression test ? Does it have a noticeable miss ? Like it’s running on 3 cylinders ?

 

I coolant disappearing?
Looked at the timing chain?

 

timing chain and coolant are both as they should be.

occasional hard shift, or diminished horsepower, constant rough idle.

played the switch around game with plugs and coils, had compression test done.
adding fuel rail to list, will update.

 

Obviously space aliens.
Whatever "as should be" means.

 

What was the pressures from the compression tests?

 

Guess he’s not coming back.