Engine rebuild or engine change? big dilemma.... - Toyota Yaris Forums

ncp13 · 01-30-2017, 03:39 AM

If you still have a misfire with P0301 try to follow the diagnostic proccedure

You said that your mechanic swaped injectors and that did not change anything correct? So that tells us that the injector was ok.

Swap the coils from the misfiring cylinder with another one 2 or 3 or 4.
Cylinder 1 is closest to your timing chain or oil fill cap.

If your DTC changes to P030( the cyl# from where you swapped the coil) you have your bad coil.

Another common failure is Coil failure from oil leak to the injector coils. You will see when you remove them if they are filled with oil.

And the if you still have no luck do a leak down test , or a compression test on the cylinder that gives you the DTC. If you get low reading you then have a misfire from low compression on that cylinder.

If you poor a little oil on that cylinder and the compression goes up its usually piston rings.. or cylider damage. If nothing changes with the oil the source of the low compression is further up from the valves. ( burned or bend valve, etc.. )

Good luck.

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01-30-2017, 03:39 AM	#20
ncp13 Drives: 01 Yaris TS Join Date: Jan 2017 Location: Athens Greece Posts: 92	If you still have a misfire with P0301 try to follow the diagnostic proccedure You said that your mechanic swaped injectors and that did not change anything correct? So that tells us that the injector was ok. Swap the coils from the misfiring cylinder with another one 2 or 3 or 4. Cylinder 1 is closest to your timing chain or oil fill cap. If your DTC changes to P030( the cyl# from where you swapped the coil) you have your bad coil. Another common failure is Coil failure from oil leak to the injector coils. You will see when you remove them if they are filled with oil. And the if you still have no luck do a leak down test , or a compression test on the cylinder that gives you the DTC. If you get low reading you then have a misfire from low compression on that cylinder. If you poor a little oil on that cylinder and the compression goes up its usually piston rings.. or cylider damage. If nothing changes with the oil the source of the low compression is further up from the valves. ( burned or bend valve, etc.. ) Good luck.